tbichips.com (Brian Harris). Useful or Not?

[DanofMostTrades]

I was about to spend a lot of money based on his recommendations page, until I read some pretty negative posts about him. Who has experience with him and does his site have good info?
Thanks in advance, any info would be appreciated.

[dave w]

I was about to spend a lot of money based on his recommendations page, until I read some pretty negative posts about him. Who has experience with him and does his site have good info?
Thanks in advance, any info would be appreciated.
I recently visited the TBI Chips website, I noticed he does not list TunerPro RT for tuning software. Most of the members here use TunerPro RT to tune with. TBI Chips lists WinALDL, which some of the members here consider OBSOLETE, and DataMaster TTS which is good tuning software for most 93 ~ 95 TBI systems. TunerPro RT has evolved over the years and can be used with many different EFI systems, not just TBI systems. Some new members here with novice PC computer skills have been challenged getting TunerPro RT configured. Maybe WinALDL and DataMaster TTS are easier to configure for those who have novice PC computer skills? TunerPro RT can be used as freeware, but I recommend paying the suggested $39 donation.

dave w

[lionelhutz]

I think his site has some decent info. I can't say if it's all good or not. There have been lots of complaints about the tuning over the years. It's best to confirm between a few sources before committing to anything.

[BLG355]

I have experience with him. I won't bash the guy even though I have every right to. My advice is go the other way, he will waste your money and time. Search for my name and you will see the experience I had with him all here in black and white.

As far as the info on his sight, he totally contradicted his own web sites information while I was working with him. I actually built my truck based on the recommendations on his website, then he told me is was a bad build and that it can't be tuned. I have some logs posted that prove it's a solid build and my truck runs awesome now thanks to this place. I went through six of his chips and they all ran very poorly, and it really wasn't even drivable. The truck ran better with the stock chip. I paid someone here for a tune and their stater chip ran awesome, and I took over tuning it from there (with all the support of this site) and never looked back. I'm still working and tuning mine a little at a time. It's not my daily driver so I can play with the tune and try different things without having to worry about it.

The nice thing about his site is there is dyno proof to back up the builds, you can base yours off that and see where you think it may fall and go from there. It also gives you some rough ideas, but there is nothing there that isn't here.

BLG

[steveo]

speed density tuning is a long process and shouldn't be trivialized, and anyone that says they can nail it on the first try is probably full of it.

i've seen tbichips tunes with minimum and maximum blm really tight so the trims never wander too far from 128, just so his VE tables look like they're working. that's pretty shady indeed.

[RobertISaar]

anyone that says they can nail it on the first try is probably full of it.

or has a really fast and loose definition of good enough.

[DanofMostTrades]

Thanks everyone for your input. Dave, I have downloaded TunerproRT and when I get a motor setup I will definitely use it. After reading what you all have said and doing lots of research I know I will definitely not buy a chip from tbichips.com.
My concern right now is building or buying a motor that is suitable for TBI and maybe a carb if I give up on TBI. I want a sturdy reliable motor with good torque and decent HP. It will be going in an 87 Chevy 4x4* that's lifted with 35's. Here is a list of what I am considering, I believe this motor produces around 260HP:

Chevrolet Performance#809-12530283 L31 HD Vortec motor for 96-2000 3/4 ton and 1 ton trucks.

Specifications:*1986-2000 style block, 4 bolt mains1pc rear seal nodular iron crankshaft
Powdered metal connecting rods
Hypereutectic pistons
9.4:1 compression Ratio.
Hydraulic roller camshaft: Int Lift .414", Exh Lift .428", Int Duration @.050" 191, Exh Duration @ .050" 196, Lobe Centerline-111
Vortec cylinder heads - 64cc, 1.94'' intake valve, 1.50'' exhaust valve
Also includes: Oil pan, timing cover, valve covers, harmonic balancer
$2029.00

Edelbrock#350-2116* Performer Vortec intake and a tbi adapter plate (I'll make the plate myself).
$193.

Summit headers SUM-G9006-9
1.5" primaries 3" collector.
$230

Let me know what you guys think about this so far. I appreciate any input.

[dave w]

I've tuned similar engines like the one posted above. I would recommend a 670 CFM Throttle Body with injectors able to flow up to 80 lbs with an adjustable pressure regulator. I would also recommend upgrading to the 16197427 94 ~ 95 TBI computer.

dave w

[fastacton]

I second Dave's recommendation on the throttle body and ECM. I just swapped over to the larger throttle body on a similar engine and it was a big help. I tuned it first with the 7747 but am about to swap over to the 7427 whenever I have time to start tuning again.

[lionelhutz]

I like the engine but personally I'd put a little more cam in it.

[Hog]

That engine is a stock Vortec 350 with 4 bolt mains. Its rated at 255 sae net hp @ 4600rpm/330 sae lb/ft torque@2800rpm.

Put it on an engine dyno and you will see about 310-320hp. The stock Vortec 350 engine is the Chev Performance 350HO/330hp crate engine with a slightly milder roller cam. TCHev Performance Parts charges you almost $1000 more for the same engine that has its 191º/196º roller cam and roller cam equipement swapped out for a flat tappet cam and its flat tappet equipement. Marketing hype, buyer beware.
The 350HO runs that flat tappet 212º/222º cam 0.435/0.460" lift (based on the 65-67 327 IIRC) it has a slightly choppy idle, while the 282(2bolt) and 283(4 bolt) Vortec 350's run the 191º/196º 0.412"/0.428" 111ºLSA roller cam that was used in the 94-96 iron headed Caprice LT1(Impala SS) sedans and wagons and Cadillac 350's, as well as the 94-94 4.3 V8(yes VEE 8) L99 engine (200hp/240 lb/ft torque), this cam was also used in every 230hp@4600rpm/285lb/ft torque@2800rpm Vortec 305(rpo L30) AND 255hp/330lb/ft Vortec 350 (rpo L31) from 1996-2003.
Lets just say its a very popular roller cam for OEM GM applications requiring solid low rpm torque.

The 350 hp Ramjet 350 that everyone gets horny about is merely the engine you are looking at, with 3 basic differences
1) the Ramjet 350/HT383/GM Marine 196º206º 0.431"/0.451? 109ºLSA roller cam,(worth about 10hp)
2)1.6:1 full roller rockers(worth about 10hp)
3)of course the Ramjet intake manifold (LT1 intake for Vortec heads)(maybe 10hp with its short runners vs. the runner design of a dual plane carb intake)
So all tolled, the Ramjet 350 and its 350 hp rating is the Vortec 350 (p/n 283) engine with about 30 hp or 6% more power. The big claim to fame of the Ramjet crate IMO, is that its a self contained injected engine where you add fuel, electricity and whammo you have an EFI engine. But even these engines require recalibration as they are horribly rich at WOT, but I understand what GM is doing. Rich is safe and will help when marginal fuel systems are used.

I personally would use a 1 5/8" primary header. (but your 1 1/2" primaries will work great for off idle torque.
I would also use the Edelbrock Performer RPM Vortec intake as it helps with power while not loosing torque whatsoever off idle.
For warranty reasons the cam would stay. I shift that cam at about 5500rpm for best et. due to the huge rpm drop of the wide ratio 700r4/4l60e trans, even though the stock 4.3 Vortec V6 DCLF TC I use helps a lot with that.

You've got a solid foundation there, I often recommend that 12530283 engine to anyone who is considering rebuilding, freshening or otherwise paying a machine shop to do a stock rebuild on a TBI 350 or Vortec 350. For $2000 you get yourself a roller cam equipped 300+hp 350, with forged PM rods, a strong nodular iron crank and hypereutectic pistons.

Shop around I sometimes see that engine for $1800, Jegs, Summit, Crate Engine Depot, SDPC all have varying prices on the same 4 bolt 12530283 4 bolt Vortec 350 engine. I have beat the snot out of my 2 bolt version, with hundreds of 1/4 mile passes, thousands of street 0 to whatever WOT passes, 0ver 300,000 miles of daily driving/winter/summer miles and the only time I had to pull a valve cover was to swap out some intake gaskets. (I suggest the FelPro problem solver and yes they are ridiculously expensive, but will pay for themselves in the long run. Esp since you are planning to run an aluminum intake on your iron heads. These GEN 1E Vortecs have the 8 intake bolt in a vertical fashion, and clamp down on the gaskets at an angle which cause the gasket to roll under intake torque and induces a shear stress as the gasket rolls as the aluminum and cast iron expand and contract at DIS-similar rates. The stock Vortec 305/350 encapsulated silicone intake gaskets back in 1996 when the Vortec 305/350 came out were branded as re-useable. This proved hugely false, and GM went through a couple versions, but Felpro came up with a steel structure/rubber coated version which stand up much better than the plastic OEM GM versions.

Since I went with these gaskets, as well as with the marine intake manifold(which features a cast iron lower manifold and aluminum upper plenum(while the stock Vortec 305/350 96-03 truck manifold had an aluminum lower and plastic upper) I have had zero gasket issues. The OEM GM 11 lb/ft intake bolt torque final spec is a little low, I tend to exceed that by a few lb/ft.

In the Centralport Sequential Fuel Injection (CSFI) 96+ applications, the poppet injectors flow 23.4 lb/hr@ 63 psi of fuel pressure. The marine intake I am running uses a 25 lb/hr EV6/Multec 2 injector to fuel the marine 350/377/383 marine engines with ratings from 260-340hp. I had the stock marine injectors flow tested and they were all pretty close to 25 lb/hr at 43.5psi or 3BAR of rail pressure, the marine fuel pressure regulator operates at 58psi or 4BAR of fuel rail pressure which brings these injectors up to approx. 28.9 lb/hr.
The OEM Vortec 350 FPR operates at 63 psi which has the poppets flowing at 23.4 lb/hr.

Your setup with this Vortec 350 longblock with headers and intake will easily be outpowering the 230hp/385 lb/ft 1990 454SS engine, and the uprated 405lb/ft 1991-1993 454SS TBI truck engines. And will do so with the lighter smallblock design, lighter transmission, and do so besting the 454 TBI's 9/10 mpg 1990 230hp 454 engine/3l80(thm-400) 3.73 gearing combo and the 10mpg/11mpg highway 1991-93 255hp/4l80e 4.10 gear combo.

My buddies hated my 1997 Vortec 350, 3.08 gear, 4l60e truck when racing their 454SS trucks. I would run right beside their 1990 SS chipped/exhaust trucks when I was stock, running the 1/4 ,mile beside them using only 1st and 2nd gear(trapping at 5500rpm in 2nd). When I went to a 4.10 gear, PCM tuned combo, I was embarrassing them and they didn't want to play, esp. the one guy that had the uprated 1991 version.

There was a 1996 1 ton van application which used a Vortec 350 with a TBI intake designed for the Vortec heads. IIRC This combo was rated at 235hp and 340 lb/ft torque. This the intake that Chev Performance Parts(was GM Performance PArts) sells for aftermarket TBI usage on Vortec/Fastburn/Bowtie Vortec heads.
This TBI/Vortec combo was also used on some export trucks as well. This OEM Vortec combo used the BBC 2" throttle bores, and specific injectors that were not the BBC injectors, nor the "Cop Car" injectors. It even had its own BroadCast Code of BRDW which is for the export Vortec engine/TBI engine.

1project2many (http://1project2many) supplied the calibration in post 19 of this thread.
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?408-fuel-curves-for-7747-running-stock-vortec-shortblock

One of the best things you can do for your squarebody TBI truck on 35's, is to ensure that you are geared correctly. I daily drove with 4.10's on 27" tires, so you should be on at least the same or lower gearing such as a 4.56, esp. if running an OD trans.

Good luck man, the ECM tuning will make or break you combo. Mr Harris is a nice guy and means well, and has some excellent combos. But the guys here seem to uncover many issues with his chips.

Sorry for the novel, but having done lots of Vortec 350 work, I get excited about these good old GEN -1E engines. No matter what is said, the newer engines do not match these off idle torque.

Keep us filled in on your project.

peace
Hog

[DanofMostTrades]

I've tuned similar engines like the one posted above. I would recommend a 670 CFM Throttle Body with injectors able to flow up to 80 lbs with an adjustable pressure regulator. I would also recommend upgrading to the 16197427 94 ~ 95 TBI computer.

dave w

As far as the throttle body, are you talking about the Holly 670 cfm or are you talking about a bored out stock unit? What is involved and what are the advantages to upgrading the computer?

[DanofMostTrades]

Wow Hog, thanks for all the info, it's exactly what I was wanting to hear. I've done a lot of research and read a lot of posts about that motor and felt pretty confident about it, but now I'm ready to order it. I do plan on putting at least 4.88's if not 5.13's under it. Will I have any issues with my stock 700r4 and this motor? Thanks again. I attached a pic of my truck. I'm really excited to get it running again.

[Engine07]

One thing I always recommend on gearing as I do quite a bit of transmission work is to take what size gears the calculator averages as stock performance equivalent and go up one size from there on mud tires if that's what your 35's are. Example is most calculators show 4.56 being ideal for 35's but they do not take thing into account things such as the extra weight associated with the larger tire as extra rotating mass is the reason I usually recommend 4.88 minimum if you will be doing a lot of highway driving or 5.13 if you will be play toy mostly offroad and mileage isn't an issue. The gearing is going to play a major part in the transmission life as well as if it is mostly just highway driven vs hard offroad use. If the transmission is mostly easy street driven it can hold up a long time with proper gearing. If it is beat on hard offroad the gears will help it last longer but it's days will be numbered. 4x4's main failures in 700r or 4l60e is in the sunshell and the input shaft to drum from shock loads. It can be built to handle it but in its stock form it is a light duty transmission being used in a heavy duty form being offroad. Just remember to be easy on it and it will be much happier.

[lionelhutz]

It's the original 87 700R4? It could become an issue, especially since it has wear and tear on it.

[dave w]

As far as the throttle body, are you talking about the Holly 670 cfm or are you talking about a bored out stock unit? What is involved and what are the advantages to upgrading the computer?

The Holley Throttle Body is one of the 670 CFM options, the other 670 CFM Throttle Body option is the Big Block Chevy 454 Throttle Body.

The 93 ~ 95 TBI computer with Red / Blue connectors is 8192 Baud / 64K PROM. The early TBI computer is 160 Baud / 4K PROM. The 93 ~ 95 TBI computer with Red / Blue connectors is about 51.2 times faster and the PROM has 16 times more memory.:thumbsup:

Don't tell anyone about the Red / Blue TBI computer, prices might increase.:mad1: The Red / Blue TBI computer is the secret to an AWESOME TBI system!

dave w

[DanofMostTrades]

It's the original 87 700R4? It could become an issue, especially since it has wear and tear on it.
The guy I bought it from said he just had it rebuilt with a shift kit, but he also said a lot of things that turned out to be false. It does have good solid shifts and the TC looks brand new so maybe it is.

[DanofMostTrades]

The Holley Throttle Body is one of the 670 CFM options, the other 670 CFM Throttle Body option is the Big Block Chevy 454 Throttle Body.

The 93 ~ 95 TBI computer with Red / Blue connectors is 8192 Baud / 64K PROM. The early TBI computer is 160 Baud / 4K PROM. The 93 ~ 95 TBI computer with Red / Blue connectors is about 51.2 times faster and the PROM has 16 times more memory.:thumbsup:

Don't tell anyone about the Red / Blue TBI computer, prices might increase.:mad1: The Red / Blue TBI computer is the secret to an AWESOME TBI system!

dave w

Thanks Dave. Here is a computer I found on ebay: http://m.ebay.com/itm/391042139144?nav=SEARCH
Does this look like a good deal?

[Fast355]

speed density tuning is a long process and shouldn't be trivialized, and anyone that says they can nail it on the first try is probably full of it.

i've seen tbichips tunes with minimum and maximum blm really tight so the trims never wander too far from 128, just so his VE tables look like they're working. that's pretty shady indeed.

I can generally get them driveable in 1 or 2 stabs. The last Vortec head, cammed 350 TBI setup I tuned using the abysmally slow 7747 data stream I had on the money in about 6-7 burns total. It was running well after about 3 or 4 but he was not running enough fuel pressure and moved the MAP sensor vacuum port on his Holley TBI per my recommendation from the rear to the front. Its a defect that applies only to Holley TBIs that creates an artificially high map signal at idle due to the IAC. Last I spoke with him he is still running the Holley TBI @ 21 psi fuel pressure which a well known TBI tuner told him is impossible to tune for.

[dave w]

Thanks Dave. Here is a computer I found on ebay: http://m.ebay.com/itm/391042139144?nav=SEARCH
Does this look like a good deal?

Seems a touch on the high side for price, considering it's supposed to be a 350 Memcal and you don't have to waste time searching a salvage yard to pull one from, it's still a fair price.

dave w

[DanofMostTrades]

Thanks for everything so far guys. I have continued my research and played with TunerproRT, and I think I can do this. I ordered my Vortec crate motor over the weekend and it should be in tomorrow. Next thing on my list is tuning equipment. I think I'm going to order the APU1 AutoProm package, a G1 adapter and S2 ZIF. Does this sound like the right combo for the 427 ECM I'm going to get?

[dave w]

My personal choice would the Ostrich 2.0 emulator, which eliminates the need for a chip!:thumbsup: The emulator allows updating the .bin file, even with the engine running.:jfj:

dave w

[DanofMostTrades]

My personal choice would the Ostrich 2.0 emulator, which eliminates the need for a chip!:thumbsup: The emulator allows updating the .bin file, even with the engine running.:jfj:

dave w

I must be confused. So, if I buy the Ostrich 2.0, wouldn't I still need a chip burner/reader so I can drive without my laptop once I get it tuned right? According to Moates.net the "APU1 AutoProm package" is an all-in-one burner/reader, datalogger, emulator that comes with Emulator cable, ALDL cable and 2 chips. Does the Ostrich 2.0 have a better emulator function than the APU1?

[dave w]

I like the lower price of the Ostrich 2.0, which only emulates. If you plan to tune several vehicles, than the added cost of the APU1 makes more $en$e.

I've helped with several remote tunes. After the tuning was finished, the Ostrich 2.0 was removed and a "burned chip" was installed for the long term.

dave w

[DanofMostTrades]

I like the lower price of the Ostrich 2.0, which only emulates. If you plan to tune several vehicles, than the added cost of the APU1 makes more $en$e.

I've helped with several remote tunes. After the tuning was finished, the Ostrich 2.0 was removed and a "burned chip" was installed for the long term.

dave w

Ok, I think I get it now, the Ostrich 2.0 stays connected to the ECM and you can just pull it out and hook up to it when you want to change your bin. Before I order it, is that all I need? Do you solder the MP socket that comes on the cable to the board or do you have to buy an adapter? I think you just saved me a lot of money, thank you so much.

[dave w]

You will need a Moates.net G1 adapter board, see attached picture.

dave w

[Six_Shooter]

Just to say it explicitly. You don't need the laptop connected to the emulator to run the engine. The bin file is loaded to the Ostrich and is read by the ECM from it, even without a laptop connected to the Ostrich 2.0.

The Emulation allows real time tuning to happen which is a great thing.

I have 4 (I think) Ostrich 2.0s now, one is installed in my car, one is in my tuning bag, and the others are back ups, or when I want to use one on my test bench, or leave one in a friend's car for a few days. I also have an AutoProm, Burn2, ALDL Xtreme, among other Moates tuning equipment.

As far as what to buy, that's a personal choice. I started with an ALDL Xtreme and Ostrich 2.0, since I already had an old programmer at the time. If you don't have anything, and you don't plan to leave the emulator in the vehicle, then an AutoProm is a great choice to have all in one capability, single cable to the laptop solution that has extra inputs to log signals that are not in the ALDL datastream. This is my go to piece when I'm tuning other people's cars. If you plan to leave the emulator in the vehicle, I would suggest the Ostrich 2.0, simply because it's a lot smaller and seems like it would handle the heat cycles and moisture better than the AutoProm, though this is really based on my dislike of leaving complex devices in such an environment. If you need to log extra signals, such as a WBO2, because you are using an ECM that is not possible or difficult to get that info through the ECM inputs, then the AutoProm makes sense here regardless.

There are people that have gone the Ostrich 2.0 and ALDL Xtreme, without a programmer and simply downloaded their BIN file or one close from a source, like gearhead-efi.com and used the emulator indefinitely. Personally I like to have the option of programming an EEPROM just in case.

What ever way you decide, you can't go wrong with Moates equipment.

[Fast355]

I recently visited the TBI Chips website, I noticed he does not list TunerPro RT for tuning software. Most of the members here use TunerPro RT to tune with. TBI Chips lists WinALDL, which some of the members here consider OBSOLETE, and DataMaster TTS which is good tuning software for most 93 ~ 95 TBI systems. TunerPro RT has evolved over the years and can be used with many different EFI systems, not just TBI systems. Some new members here with novice PC computer skills have been challenged getting TunerPro RT configured. Maybe WinALDL and DataMaster TTS are easier to configure for those who have novice PC computer skills? TunerPro RT can be used as freeware, but I recommend paying the suggested $39 donation.

dave w

Some may consider WinALDL absolete, but it is still one of the easiest things to use for many GM vehicles and has many pre-configured history tables.

[DanofMostTrades]

Seems a touch on the high side for price, considering it's supposed to be a 350 Memcal and you don't have to waste time searching a salvage yard to pull one from, it's still a fair price.

dave w
Making progress, ordered my Ostrich 2.0, and G1 adapter, then after work I found this at Pick N Pull today for $28, with a 6 month warranty.

[dave w]

That seems to be very good deal. The BJYK Memcal, based on the information available to me, is from a 1995 5.7 Liter / Automatic Trans.

dave w

[DanofMostTrades]

I was not looking forward to repining my stock wiring harness for the 427 PCM, so instead I made an adapter with the plug from my old ECM. If anyone sees a reason this won't work, let me know. The only question I have is in regards to Pins E14 (MAP Reference/5 volt Ref) and F14 (TP Reference/5 volt Ref) which according to the pin out spreadsheet both go to Pin C14. There aren't any notes about it and the chart with color codes shows pin C14 going to pin E14 only, it doesn't mention F14. I soldered both wires to pin C14, am I going to fry something by doing this?

[fastacton]

I think there are a few of us that have made similar adapters with good results. I've got E14 to C14 and nothing to F14. I don't think you'll fry anything hooking up both, but there's not a need to.

[fastacton]

Making progress, ordered my Ostrich 2.0, and G1 adapter, then after work I found this at Pick N Pull today for $28, with a 6 month warranty.

Your Pick-n-Pull has much better deals than the ones I go to! That would be around $60 out the door with a 30 day warranty around here.

[DanofMostTrades]

Your Pick-n-Pull has much better deals than the ones I go to! That would be around $60 out the door with a 30 day warranty around here.

I believe she rang it up wrong, then she saw the wiring after I had paid and said, "Oh well". And the 6 month warranty kinda blew my mind, so I was very excited to get it out the door for $28, plus it looks perfect inside with no signs of corrosion. If F14 is not needed, I will disconnect it just to be safe, thank you.

[Six_Shooter]

Adapters are a good way to go, at least for testing and proofing. I've made several adapters over the years for various applications. '7747 to '7730/7749, '7148 to '7730/'7749, '7730/'7749 to '7165 and a couple others. I'll be making a couple more this summer to go between the current harness and a couple aftermarket ECMs.

I'm pretty sure there's another thread (or two) floating around with other people's adapter harnesses, but here is one I started, that shows the use of some DB computer connector pins that works far better than soldering the wire straight to the pin of the donor connector. http://www.gearhead-efi.com/Fuel-Injection/showthread.php?944-Finally-getting-another-Delco-project-done-or-started&

--==EDIT==-- Here's another thread: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1122-building-a-C3(747)-to-P4(730)-adapter-harness&

[DanofMostTrades]

Ok guys, I've been hard at work getting this motor ready, trying to weed out every problem I can before installing it. As of last night it is in the truck and almost ready to go. I'm now in need of a starter bin to go on my Ostrich 2.0. Here is my setup:

96-2000 4 bolt main vortec longblock bone stock.
Edelbrock performer RPM vortec intake. No egr.
Stock 350 tbi with the ultimate tbi mods, and AFR.
Stock injectors.
Upgraded fuel pump.
long tube headers, 1.5"prime to 2.5" collector. O2 in collector. True dual 2.5" exhaust no cats.
700r4 transmission and transfer case (4x4).
Running a 427 pcm from a 95 350 auto truck.(my truck is an '87)

My guess is it will make around 270-280HP. Does anyone have a similar build that would be willing to share they're bin? I'm new to tuning and would like to have a good starting point.
Thanks in advance.

[Fast355]

Ok guys, I've been hard at work getting this motor ready, trying to weed out every problem I can before installing it. As of last night it is in the truck and almost ready to go. I'm now in need of a starter bin to go on my Ostrich 2.0. Here is my setup:

96-2000 4 bolt main vortec longblock bone stock.
Edelbrock performer RPM vortec intake. No egr.
Stock 350 tbi with the ultimate tbi mods, and AFR.
Stock injectors.
Upgraded fuel pump.
long tube headers, 1.5"prime to 2.5" collector. O2 in collector. True dual 2.5" exhaust no cats.
700r4 transmission and transfer case (4x4).
Running a 427 pcm from a 95 350 auto truck.(my truck is an '87)

My guess is it will make around 270-280HP. Does anyone have a similar build that would be willing to share they're bin? I'm new to tuning and would like to have a good starting point.
Thanks in advance.

I think you are under estimating the HP. Iys more like 300-310 hp. You are going to need either larger injectors or alot more fuel pressure. I have a decen bin file I could dig up but you will need to increase your injector flow before it will ever run right.

[DanofMostTrades]

I think you are under estimating the HP. Iys more like 300-310 hp. You are going to need either larger injectors or alot more fuel pressure. I have a decen bin file I could dig up but you will need to increase your injector flow before it will ever run right.

So, where does the 40-50 extra HP come from? Is Chevy's rating of 260 HP just that far off? (I'm not challenging your knowledge, im just curious.) And how much fuel pressure will I need to run with my stock injectors? 18-20psi? Thank you, I would greatly appreciate that bin too.

[Six_Shooter]

When starting on a tune like this, I always start with a bone stock bin for the engine, or similar engine (when using a Delco on a non GM engine, or swapping ECMs between applications).

In most cases a stock bin will allow even some of the most modified engines start and run, and from there you can start tuning idle. then work your way up.

By far the hardest part to tune on any engine will be the cold start and cold run parameters, but with some care and being observant of actual fuel ratio, not just what the WBO2 gauge on your dash is telling you, you can at least get the engine to start and up to operating temp where the real tuning can begin. By real AFR I mean using your nose, eyes and touch to smell see and feel that the exhaust is either too lean or more commonly too rich after a rebuild. The reason for being too rich is because larger camshafts tend to produce less vacuum and therefore an ECM will think the engine is under more load than it really is, adding more fuel.

On fresh starts, I will, just to get the engine up to operating temp, using the injector scaler(s) (BPW, BPW vs EGR, etc) to lean out or richen the mixture using an emulator to keep the AFR is a close approximation of where it needs to be. Once warmed up. I will then find the sweet spot for the BPW, where the engine runs close to stoich without surging or stalling and start to adjust the VE table from there. Initial tunes take several attempts on the more modified engines. It will be a back and forth with adjustments, especially if you find you need some really high values in the VE table that do not allow for much overhead at the higher loads. I like to keep max VE in the VE table below 90%, to allow for any additional adjustments that may be needed later. The flip side is also true, if you need to reduce the values in the VE table so much that you're getting below about 20, then you may need to adjust the BPW/injector scaler. This is what I have found for the more wildly built engines.

Engines with mild modifications, such as an "EFI friendly" cam, some mild porting, headers, exhaust and maybe an intake tend to not be as much trouble. Using a stock bin has worked to get an engine running and up to temp in these situations without much issue, unless there is a mechanical issue (I'll get to that in a minute). Letting an engine warm up while being slightly rich is not the end of the world. I try to keep the warm up AFRs under 13:1, just to make sure that the oil won't be getting saturated with fuel, but this will usually allow for a smoother running engine when first tuning. The closer the AFR is to between 14.1:1 to 14.7:1 the better, but this may not happen until after the operating temp running tuning has begun or has been just about finished.

Just as an FYI, on my Nissan 2.8L I6 using code59, I started with a "stock starter bin (V4)", and had the engine running in a few minutes after making a couple starting fuel settings, but was running within a few minutes. I pulled the car on the road and after making a few VE table adjustments to get rid of a part throttle surge I was driving around in a car that was not supposed to run according to some "experts". ;)

So basically, start with a stock bin and you might be surprised just how close it will be to start tuning from. ;)

About those mechanical issues...

I had this trick me recently. A friend of mine recently upgraded the engine in his girlfriend's car, with a new cam, headers, 3" exhaust, ported heads, and maybe a couple other things that I don't recall right now. Anyway, we went out Saturday afternoon (a week ago), did some tuning on it, the WBO2 was kinda all over the place, and something didn't feel right. I couldn't nail the tune down, because what worked one minute didn't work teh next, and so I got into a sort of tuning circle. I kept mentioning how it seemed like there was a dead cylinder, or at least a very weak one. Lean spikes on the WBO2 that seemed almost cyclic screamed this to me. Anyway. We get back and the exhaust sounds different on each side of the car (true duals, no crossover). I suggest that he check the plugs and the cylinders when he got a chance and see if he finds anything. Sure enough, cyl #5 has issues. He fixes that, then the tune is way out. We went out last night, and I tuned the car all over again, and it's a whole different animal now. So make sure that what you are tuning has no mechanical issues. Even a new build does not guarantee that the engine is perfect. ;)

[Fast355]

So, where does the 40-50 extra HP come from? Is Chevy's rating of 260 HP just that far off? (I'm not challenging your knowledge, im just curious.) And how much fuel pressure will I need to run with my stock injectors? 18-20psi? Thank you, I would greatly appreciate that bin too.

Gross vs Net HP rating and the fact you have long tube headers and full catless exhaust rather than those god awful manifolds and tiny 1 7/8" head pipes of a factory vortec truck. Also the TBI on a rpm intake is less restrictive than the factory vortec intake manifold with all the fuel spider crap in the way. A Vortec 350 with headers, decent exhaust and a good tune is over 250 rear wheel hp. Even using a very conservative 18% loss through the drivetrain that is 305 hp at the flywheel.

It is also experience with these engines telling me you need fuel for a lot more than 250 HP.

[Fast355]

To support ~300 HP at a .5 BSFC with 2 injectors at 85% duty cycle means you need 88 lbs/hr per injector. To get 88 lb/hr from a 61 lb/hr @ 11 psi injector means you fuel pressure needs to be about 24 psi.

[lionelhutz]

I suggest that he check the plugs and the cylinders when he got a chance and see if he finds anything. Sure enough, cyl #5 has issues. He fixes that, then the tune is way out. We went out last night, and I tuned the car all over again, and it's a whole different animal now. So make sure that what you are tuning has no mechanical issues. Even a new build does not guarantee that the engine is perfect. ;)

Had a cracked plug on a F-body. It does mess things up. It seemed to be running OK except that it seemed a little flat.

[DanofMostTrades]

To support ~300 HP at a .5 BSFC with 2 injectors at 85% duty cycle means you need 88 lbs/hr per injector. To get 88 lb/hr from a 61 lb/hr @ 11 psi injector means you fuel pressure needs to be about 24 psi.

Ok, thank you for the info. I have a stiffer reg spring on the way (was hoping to get enough fp with stock spring cranked all the way down. Ha, about 15, not even close.) I already have the higher pressure pump installed.

[DanofMostTrades]

Six_Shooter, I went ahead and loaded a stock bin on the Ostrich and fired it up. I ran it for about a minute just to get my base timing set, and shut it off. I want to data log but I'm having trouble getting a data stream connection. Tuner pro recognizes my aldl cable on (COM 5) and says the cable is connected and functional, but when I try to connect it just says "DA: connecting...." forever. Any ideas what I'm doing wrong? I bought the cable from www.aldlcable.com 3 years ago and it worked fine with winaldl. I have the 427 pcm with the BJYK bin on the Ostrich and I'm using this definition: A217 $0D TP5 v250.adx. The motor started first crank and sounds great, but i need to get my fuel pressure up and stream data before I go any further. Hearing it fire up was pretty awesome, I'm very excited to get it on the road.

[fastacton]

In TunerPro, go to tools-preferences-data acq./emulation and make sure the settings there are correct.

[DanofMostTrades]

Ok, I made some progress. I got my fuel pressure up to 22psi. I got the DA connected and emulation working. What would be the best ADX for data logging, or does it matter? I'm such a newbie at engine tuning, I just don't have the touch, feel, smell experience to know how the engine is running. What parameters have to be met for it to go into closed loop? I feel I will really be relying on O2 reading to do any tuning. I'm going to do some more research for now, If anyone has any advice or tips, I'm all ears.

[Cooker]

As a fellow newbie I feel your pain! Here are a couple links to some reading material that I found helpful. Some of the hardware used is outdated but the definitions and parameters appear to be relevant.
http://www.thirdgen.org/forums/diy-prom/288763-prom-tuning-guide-book.html
http://www.thirdgen.org/forums/tbi/257455-advanced-topics-tbi-theory.html
http://www.thirdgen.org/forums/tbi/354409-come-free-tune.html

[Six_Shooter]

Good hear you got DA working.

Just about any any ADX will work fine. You may want to find one that has as many things defined as you can. The ADX we have on this site are usually some of the most defined you will find. In TP RT V5 you can create your own dashes to display what you want how you want.

Don't rely on the O2 to tune, use the data from it yes, but don't rely on it. Also realize that using a NBO2 is more of a switch than a sensor. The transition from high voltage (near 1 volt) to low voltage (near 0 volts) is a very steep transition that happens around stoich, and has very flat response on either side. This is why a WBO2 is usually suggested, because it can display actual AFR, not just an approximation.

You need to see, feel and hear what is going on. If the engine is surging, figure out why. Too lean? Too much timing? Just trying to load the engine below the cam operating RPM? Is the engine blowing black smoke? Too rich. Does the engine feel lazy lazy? Too lean? Too little timing? Too much timing? Too rich? Do your eyes water when your sitting in traffic, or near the tail pipes? Pull some fuel. Does it smell rich?.... etc.

Use common sense, if something doesn't feel right, figure out what it is that's making it not right. There's no one solution for any condition, sometimes you need to experiment with different things and sometimes you need to make drastic changes to isolate the cause, and then fine tune that condition. Don't be afraid to start over or go back to a better running tune if you feel you're heading in the wrong direction.

Most of all, give the engine what it wants.

[DanofMostTrades]

Luckily so far the engine has actually ran pretty smooth. No surging, it starts on the first turn every time and today after welding up my full exhaust system, I ran it again. This time I ran it long enough to get it to operating temp and it went into closed loop a few times. It appeared to be running pretty rich, I logged some data and will post it tomorrow. I'm hoping I can get it out of the shop and put a load on the motor this weekend. I would like to get a WBO2 but I've run my truck fund completely dry. Any nickel and dime parts have to go on the credit card for awhile. Every evening I've made progress. And seeing it go into closed loop and be rich made me happy tonight.

[Fast355]

Luckily so far the engine has actually ran pretty smooth. No surging, it starts on the first turn every time and today after welding up my full exhaust system, I ran it again. This time I ran it long enough to get it to operating temp and it went into closed loop a few times. It appeared to be running pretty rich, I logged some data and will post it tomorrow. I'm hoping I can get it out of the shop and put a load on the motor this weekend. I would like to get a WBO2 but I've run my truck fund completely dry. Any nickel and dime parts have to go on the credit card for awhile. Every evening I've made progress. And seeing it go into closed loop and be rich made me happy tonight.

Set your injector flow rate, add the vortec timing table I posted from the Suburban I tuned last summer, and then start working on you VE tables. You can put my timing map in both the off-idle and idle timing tables and take the value from 1.15 or 1.20 of the Equivalance ratio vs spark table (they are the same) and put in your PE spark advance table.

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4378-Timing-Table&p=50093&viewfull=1#post50093

[DanofMostTrades]

Set your injector flow rate, add the vortec timing table I posted from the Suburban I tuned last summer, and then start working on you VE tables. You can put my timing map in both the off-idle and idle timing tables and take the value from 1.15 or 1.20 of the Equivalance ratio vs spark table (they are the same) and put in your PE spark advance table.

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4378-Timing-Table&p=50093&viewfull=1#post50093

Do I have to manually input each number from your spark table or is there a file I can import? Not sure how all this stuff works. I'll take a closer look at it all when I get off work. I've looked at the tables on TP but haven't changed anything yet. I'm feeling accomplished just getting a data stream and loading a bin on the Ostrich. I'm using your mask: "Fast 355 $OD 700r4.xdf". It seemed appropriate for my setup.

[DanofMostTrades]

As a fellow newbie I feel your pain! Here are a couple links to some reading material that I found helpful. Some of the hardware used is outdated but the definitions and parameters appear to be relevant.
http://www.thirdgen.org/forums/diy-prom/288763-prom-tuning-guide-book.html
http://www.thirdgen.org/forums/tbi/257455-advanced-topics-tbi-theory.html
http://www.thirdgen.org/forums/tbi/354409-come-free-tune.html

Thanks for the links, they do have some useful info.

[Fast355]

Do I have to manually input each number from your spark table or is there a file I can import? Not sure how all this stuff works. I'll take a closer look at it all when I get off work. I've looked at the tables on TP but haven't changed anything yet. I'm feeling accomplished just getting a data stream and loading a bin on the Ostrich. I'm using your mask: "Fast 355 $OD 700r4.xdf". It seemed appropriate for my setup.

You would have to manually input the numbers since the tables are not exactly the same in regards to RPM/MAP values and overall dimensions.

That XDF file is one I added the TCC paramaters into for running a 700r4 or 200-4r in place of a 4L60E or 4L80E.

I am taking my grandmother to dinner tonight for her birthday, but I may be able to find and post up a Vortec .bin I made a while back for another guy with Vortec heads on a TBI 350.

[Woods]

add the vortec timing table I posted from the Suburban I tuned last summer

Where's that posted at Fast? The link when I view it doesn't show any tables other than the ones in the 1st post? Would really like to take a look at that timing table.

Thanks

[DanofMostTrades]

You would have to manually input the numbers since the tables are not exactly the same in regards to RPM/MAP values and overall dimensions.

That XDF file is one I added the TCC paramaters into for running a 700r4 or 200-4r in place of a 4L60E or 4L80E.

I am taking my grandmother to dinner tonight for her birthday, but I may be able to find and post up a Vortec .bin I made a while back for another guy with Vortec heads on a TBI 350.

I used your timimg tables and set the flowrate to 9.99 which should be right based on stock 61 injectors at 22psi and drove the truck, here is my log if anyone want to have a look. It started and idled pretty well and had decent power, but it did hesitate a lot when giving it much throttle. Hope to drive it again tomorrow. If you guys check out my log and see anything bad please let me know, I don't think its running super lean or anything but I'm really not sure. My base timing is set to 0.

[DanofMostTrades]

Where's that posted at Fast? The link when I view it doesn't show any tables other than the ones in the 1st post? Would really like to take a look at that timing table.

Thanks

I believe he was referring to the picture in post #6. At least I hope that's the timing table he was referring to, its the one I used.
8897

[Fast355]

I believe he was referring to the picture in post #6. At least I hope that's the timing table he was referring to, its the one I used.
8897

Thats the one I use, works quite well for me on stock to mildly cammed vortec head engines.

[Woods]

I believe he was referring to the picture in post #6. At least I hope that's the timing table he was referring to, its the one I used.
8897

Thanks for reposting that table. For some reason that table does not show for me in the original thread. Weird.
Good luck on your tuning, have fun with it.

[DanofMostTrades]

No problem Woods, I want to help when I can. This site has been so much help, maybe someday I can start giving back, but for now I can do the small things.

[DanofMostTrades]

Here are a few pics from my build. I'm a CNC machinist/welder/fabricator and was able to make my own TBI to square bore adapter, fan shroud and a bunch of little parts.
8908
8909
8919
8911
8912
8913
8914

8916
8917
8918

[Woods]

Here are a few pics from my build. I'm a CNC machinist/welder/fabricator and was able to make my own TBI to square bore adapter, fan shroud and a bunch of little parts.


Looks good. I really like that TBI adapter you made, very nice!

[DanofMostTrades]

Looks good. I really like that TBI adapter you made, very nice!
Thanks, it was a fun project. I should still have the program if anybody wants to buy one.

[DanofMostTrades]

Hey Fast355 , we're you ever able to find that bin you were talking about? I'd like to compare it to the tuning I've been doing.

[Fast355]

Here are a few pics from my build. I'm a CNC machinist/welder/fabricator and was able to make my own TBI to square bore adapter, fan shroud and a bunch of little parts.
8908
8909
8919
8911
8912
8913
8914

8916
8917
8918

That is very similar to the Mercruiser 2" bore to square bore TBI to carb intake adapter I have in my garage that came on a 405 hp 502 TBI.

[Fast355]

Hey Fast355 , we're you ever able to find that bin you were talking about? I'd like to compare it to the tuning I've been doing.

Really have not had a chance to dig out the tuning laptop and look. Been building a L30 305 Vortec to swap into an Astro van this weekend.

[brian617]

Thanks, it was a fun project. I should still have the program if anybody wants to buy one.

Any interest in machining an adapter for a Vortec/LS style throttle body to a Holley 4150 carb flange?

[DanofMostTrades]

Any interest in machining an adapter for a Vortec/LS style throttle body to a Holley 4150 carb flange?

Maybe, do you have some dimensions or a print I could go by? Where are you in AR?

[brian617]

Sent a PM to you.

[DanofMostTrades]

My starter .bin.

[DanofMostTrades]

I decided to bore my own throttle body and it was a success. It was a little tricky making the blades, but it came out perfect. I also got a 3 wire o2 installed and am waiting on some injectors to come back from Mr. Injector. I've done some tuning but am waiting on the flow tested injectors so I have a good base to start with. I'm saving for a WBO2, any suggestions?

[Steveshow]

A few years ago, I had a 93 GMC K2500 4x4 with an NV4500 5 speed that I swapped a 97 Vortec engine into. I scored a "CRUSADER" marine tbi to vortec intake with no egr on EBAY for $100. Based on Brian's recommendation, I installed an LT4 "Hot" cam that my brother had bought for his 1996 Impala SS but didnt use. Bad choice. No torque from that cam in a truck. It didnt have a lift or even bigger tires than stock. I swapped it for an "Extreme 4x4" grind recommended by Comp Cams (I forget the specs) . It made a WORLD of difference. The LT4 cam may have been fine in a high RPM mud truck, but not a street truck. The other problem I had was the spring he sold me for the stock fuel pressure regulator gave me the exact same fuel pressure as the stock spring (?) I tried the adjustable regulator he recommended, but it was a bear to get to and the head stripped off shortly after install. Frustrated, I installed the fuel pump from the donor Vortec truck and an aftermarket adjustable fuel pressure regulator to get my fuel pressure up to the recommended level.

I have no way of knowing whether any power was "left on the table" as I bought the truck with a blown engine, but it seemed to run and tow well for a 350 equipped truck. I always wondered how much power I was missing compared to going to a larger CFM EFI system, or 700 cfm carb. I sold it a few years ago and bought an 01 Silverado HD with a Duramax.

I am now working on a 1991 Olds Custom Cruiser wagon. It had a tired 200k mile TBI 305 that still ran with 0 lbs oil pressure indicated (!). I will be swapping another Vortec 350 into this car. I have a "take out" Ram Jet 350 cam, Comp beehive springs, full roller rockers, GMPP parts vortec to tbi intake ($150 Ebay score). Undecided if I will sheel out cash for headers, or run stock manifolds and full duals. I plan to get it running and see how it runs. Not look for a barnstormer, maybe tow a small pop up camper, etc. I see that the RAMJET intake that bolts to the vortec heads is a possible upgrade. I wonder if it would be worth the extra coin...

[Hog]

The Ramjet intake works well on Vortec 350's.

http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/Ramjetintakedynochart.jpg (http://s1202.photobucket.com/user/Paul_Schermerhorn/media/Ramjetintakedynochart.jpg.html)

From this engine, Vortec 350 Hotcam kit, 24x Coil Near Plug kit
http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/L31hotcamramjet350.jpg (http://s1202.photobucket.com/user/Paul_Schermerhorn/media/L31hotcamramjet350.jpg.html)

But swapping in an intake while using a truck torque cam doesn't make sense power/moneywise.

peace
Hog

[Steveshow]

I am already going to be running the ramjet cam. Basically i would be piece mealing a ramjet crate motor. Any source for an affordable ramjet retrofit kit? I suppose i would need a whole system with new ecu, as my car is tbi now...

[Fast355]

A few years ago, I had a 93 GMC K2500 4x4 with an NV4500 5 speed that I swapped a 97 Vortec engine into. I scored a "CRUSADER" marine tbi to vortec intake with no egr on EBAY for $100. Based on Brian's recommendation, I installed an LT4 "Hot" cam that my brother had bought for his 1996 Impala SS but didnt use. Bad choice. No torque from that cam in a truck. It didnt have a lift or even bigger tires than stock. I swapped it for an "Extreme 4x4" grind recommended by Comp Cams (I forget the specs) . It made a WORLD of difference. The LT4 cam may have been fine in a high RPM mud truck, but not a street truck. The other problem I had was the spring he sold me for the stock fuel pressure regulator gave me the exact same fuel pressure as the stock spring (?) I tried the adjustable regulator he recommended, but it was a bear to get to and the head stripped off shortly after install. Frustrated, I installed the fuel pump from the donor Vortec truck and an aftermarket adjustable fuel pressure regulator to get my fuel pressure up to the recommended level.

I have no way of knowing whether any power was "left on the table" as I bought the truck with a blown engine, but it seemed to run and tow well for a 350 equipped truck. I always wondered how much power I was missing compared to going to a larger CFM EFI system, or 700 cfm carb. I sold it a few years ago and bought an 01 Silverado HD with a Duramax.

I am now working on a 1991 Olds Custom Cruiser wagon. It had a tired 200k mile TBI 305 that still ran with 0 lbs oil pressure indicated (!). I will be swapping another Vortec 350 into this car. I have a "take out" Ram Jet 350 cam, Comp beehive springs, full roller rockers, GMPP parts vortec to tbi intake ($150 Ebay score). Undecided if I will sheel out cash for headers, or run stock manifolds and full duals. I plan to get it running and see how it runs. Not look for a barnstormer, maybe tow a small pop up camper, etc. I see that the RAMJET intake that bolts to the vortec heads is a possible upgrade. I wonder if it would be worth the extra coin...

If the LT4 Hotcam was not making torque it had a bad tune or was timed wrong. That cam will BOIL tires off even at lower RPMs. In an engine under 10:1 it needs to be advance 3° and installed on a 106° ICL.

I have a Ramjet cam and 1.7 rockers in my Express van and even pulling my 6,000 lbs Jayco travel trailer I find it lacking above 4,000 rpm which I spend ALOT of time at. On steeper hills the 4L80E is in 2nd gear at 70 mph, spinning 4,500 rpm with my foot on the floor.

With my old G-van I had a 10.5:1 Vortec head 383 with TPI using SLP runners that had been siamese ported and tri-y headers. I ran a 232/240 @ .050 cam on a 110° LSA and towed heavy with it. It had a 4L60E and 3.08 gears. Only ran a 2,600 rpm converter in it. 70 in 3rd gear was only about 2,700 rpm.

[Steveshow]

If the LT4 Hotcam was not making torque it had a bad tune or was timed wrong. That cam will BOIL tires off even at lower RPMs. In an engine under 10:1 it needs to be advance 3° and installed on a 106° ICL.

I have a Ramjet cam and 1.7 rockers in my Express van and even pulling my 6,000 lbs Jayco travel trailer I find it lacking above 4,000 rpm which I spend ALOT of time at. On steeper hills the 4L80E is in 2nd gear at 70 mph, spinning 4,500 rpm with my foot on the floor.

With my old G-van I had a 10.5:1 Vortec head 383 with TPI using SLP runners that had been siamese ported and tri-y headers. I ran a 232/240 @ .050 cam on a 110° LSA and towed heavy with it. It had a 4L60E and 3.08 gears. Only ran a 2,600 rpm converter in it. 70 in 3rd gear was only about 2,700 rpm.

Im not sure what the compression ratio of the stock vortec was, but the cam was in fact installed straight up. I did consider doing as you mentioned and advancing the cam to increase torque, but when asked,Brian only told me "it should work as is". Of course comp cams is in the business to sell cams, not give advice on how to make an existing cam work, so i guess i shouldnt be surprised that they didnt suggest advancing the existing cam.

btw, i know that a cam can be installed advanced or retarded by moving the timing gears, but how do you "alter" the centerline? This is how the cam is ground...


on a related note i dont think any cam would make a used vortec 350 with tbi in a 4x4 3/4 to. Truck with 265 70r16 all terrain tires "boil the tires"...

[Fast355]

Im not sure what the compression ratio of the stock vortec was, but the cam was in fact installed straight up. I did consider doing as you mentioned and advancing the cam to increase torque, but when asked,Brian only told me "it should work as is". Of course comp cams is in the business to sell cams, not give advice on how to make an existing cam work, so i guess i shouldnt be surprised that they didnt suggest advancing the existing cam.

btw, i know that a cam can be installed advanced or retarded by moving the timing gears, but how do you "alter" the centerline? This is how the cam is ground...


on a related note i dont think any cam would make a used vortec 350 with tbi in a 4x4 3/4 to. Truck with 265 70r16 all terrain tires "boil the tires"...

When you advance or retard the cam you change the intake amd exhaust centerline in relation to the crankshaft. The LSA or LCA is what is ground into the cam and cannot be changed.

My cammed L31 BOILS the 255/70R15s in my heavy Express van despite having a 4L80E with a very tall first gear and 3.73s.


This was the aftermath of a burnout on dry concrete.

http://i243.photobucket.com/albums/ff172/Fast355_album/20141221_174512_zps8r032gyj.jpg (http://s243.photobucket.com/user/Fast355_album/media/20141221_174512_zps8r032gyj.jpg.html)