Advise needed, planning a 383 build for a 1988 C1500 Pickup

Hello I am new to the idea of tuning the factory TBI and have been cruising this board for awhile. One question I have in my head is "What are the limits of cam size/vacuum signal that will work with the map sensor in this type of fuel injection?" I am not looking for something radical, just a peppy truck engine that will pull a load.

Plan so far
350 block bored .030 (already finished)
383 kit with 6 inch rods (already have)
afr 195 heads 75cc chambers (to give 9.5 to 1 compression) or equivalent due to the price of AFR's
Roller Cam (no size determined yet)
Good long tube headers and dual exhaust.

Any other thoughts would be welcome. Truck has the 1227747 PCM I believe

Sounds like a fun build. As much as the 383 will breathe you'll need a bored out (46mm) TBI with higher pressure or maybe even a 50mm from a 7.4. On the bottom of this link you can estimate what you may need...

http://www.tciauto.com/tc/racing-calculators

Here's where I bought my 46mm with 18# spring. It comes with new IAC, and TPS, with voltages preset.

https://www.ebay.com/str/sprperformance

If you can afford it try the Dynamic EFI conversion

https://www.dynamicefi.com/EBL_Flash.php

So many options, so many opinions, but I recognize budget is a factor.

Reground camshafts can save money, often a performance camshaft profile can be ground into an original camshaft (but there are limits) I sure there are several members with Pro / Con OPINIONS about using a reground camshaft. For a mild built daily driver 1993 K1500 5.7 liter with TBI (weighing in a 5200 lbs.), I opted for an ultra low cost reground Vortec 5.7 liter roller camshaft (stock lift / stock duration). With the savings from the reground camshaft, I invested in some ultra expensive 1.6 ratio roller tip rocker arms. I was able to tune the reground camshaft / 1.6 ratio rocker arms to a performance of 0 MPH to 60 MPH is about 7 seconds (which is the kind of performance that gets up and goes from a stop light to the end of the freeway on ramp with a smile).:thumbsup:

Used SBC parts are not unique, rare or hard to find. Generally performance SBC parts are becoming more abundant, with the rise in LSx engine popularity.

Hopefully you can budget for a better performing head than the 195's (my own personal opinion).

The 7.4 liter 670CFM throttle body is a good option, but can create some headaches.

I posted an article several years ago "1227747 R.I.P." so I'm not going to hide my opinion that the factory 16197427 is a better computer for a performance engine on a budget.

I'm also Opinionated that it's good plan to budget for tuning equipment, simply stated tuning will optimize the performance of the parts decided on.

I'm also Opinionated that an "Optimal Chip" Can Not be programmed with the information "Tell us what modifications were done". I'm so flat out Opinionated about TBI performance chips, that I BOLDLY SAY use TunerPro RT or just keep chasing tail lights like everyone else who doesn't use TunerPro RT!

dave w

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Plan so far
350 block bored .030 (already finished)
383 kit with 6 inch rods (already have)
afr 195 heads 75cc chambers (to give 9.5 to 1 compression) or equivalent due to the price of AFR's
Roller Cam (no size determined yet)
Good long tube headers and dual exhaust.

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Is your block an 88 too? Is it set up for a roller cam?

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Originally Posted by PlayingWithTBI

Is your block an 88 too? Is it set up for a roller cam?

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THe Block I have at the machine shop is out of a 1993 but has been drilled for the roller setup. I have a 1993 4wd 2500 that I robbed the engine from. If the computer would be better I might could try to adapt it. I have wondered if a newer pcm would be better since 1988 was a long time ago computer wise. I would think a newer one with a newer processor would think faster

I am planning on a roller cam. Was looking at the Comp 08-465-8, but open to suggestions.

I was looking at possibly getting the TBI bored when I get closer. I am not sure at the moment which injectors the TBI has, nor if they will feed a bigger healthier engine.
I have already installed the 1996 Vortex fuel pump in the tank (because the stock one died).

I just googled the stock TBI and it's quoted as good for 450-480cfm. Is this figured with fuel spraying through it? Carbs too? Cause the fuel itself takes up space.

That cfm calc shows my truck should have about 500cfm. But with an MPFI conversion and dry throttle body maybe a wet 470 is enough?

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Originally Posted by Redtires019

I have a 1993 4wd 2500 that I robbed the engine from. If the computer would be better I might could try to adapt it. I have wondered if a newer pcm would be better since 1988 was a long time ago computer wise. I would think a newer one with a newer processor would think faster

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The 1993 TBI computer is most likely part number 16168625, which has a baud speed of 8192. The 1988 TBI computer has a baud speed of 160.

dave w

Save some money for your transmission;)

If you want a cheap cam- get the BIGGER of the LT1 variety.

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Originally Posted by Redtires019

THe Block I have at the machine shop is out of a 1993 but has been drilled for the roller setup. I have a 1993 4wd 2500 that I robbed the engine from. If the computer would be better I might could try to adapt it. I have wondered if a newer pcm would be better since 1988 was a long time ago computer wise. I would think a newer one with a newer processor would think faster

I am planning on a roller cam. Was looking at the Comp 08-465-8, but open to suggestions.

I was looking at possibly getting the TBI bored when I get closer. I am not sure at the moment which injectors the TBI has, nor if they will feed a bigger healthier engine.
I have already installed the 1996 Vortex fuel pump in the tank (because the stock one died).

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I have a comp cam 08-466-8,. made 375 FHWP/420ft lbs FWTQ on the dyno in a 355 with vortec heads. it also had stamped steel 1.5 rockers, i would highly recommend full rollers. has about 100 hours on it. engine is getting recamed and going in a boat so cam needa a new home.

http://www.compcams.com/Company/CC/c...?csid=208&sb=0

375 FHP/420ft lbs FWTQ.....was that with TBI on it or a carb?

Stock L31 Vortec cam specs
10241264 casting number
Intake lift- .414” with 1.6 rocker arms .442
Exhaust Lift- .428" with 1.6 rocker arms .457
Intake duration @.050"- 191*
Exhaust Duration @ .050" - 196*
Lobe Centerline- 111 Degrees

I like the 111 Degrees for the Lobe Centerline of the L31 camshaft (smooth idle / good vacuum). I like the added lift the 1.6 rocker arms provide to the L31 camshaft. Roller tip rocker arms provide a more accurate lift ratio than stamped steel rocker arms. Depending on brand, stamped steel rocker arms have been measured at 1.42 ratio not 1.5 ratio.

The LT1 for the 94-96 Buick Roadmaster, Chevrolet Caprice, and Cadillac Fleetwood have the same Lobe Centerline of 111 Degrees as the L31 camshaft with slightly more lift .418 / .430.

dave w

I think there was another cam for the Z28/Corvette- the 383 should swallow that with no issues.

I had a 355 TPI with a CC flat tappet, very noisey lobes, ended up using a stock vortec roller- with a nice tune it worked very well with 1.6 RR. Not a fan of CC ever since.

For tuning purposes, I often use a factory camshafts and related spark tables. For example using a LT1 camshaft matched with the LT1 spark tables programmed in the chip, is a good plan for a "Starter Tune". The final "tuned chip" might have all, some, most, or none of the original timing table (that called tuning). The original TBI timing table works well with the original TBI camshaft. It's fair to say the original TBI timing table can be improved with the original TBI camshaft too.


dave w

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Originally Posted by dave w

Hopefully you can budget for a better performing head than the 195's (my own personal opinion).

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What head do you prefer? I am open to considering all options. I need a 76cc head to work with the pistons I have and the 195 runners should be close for a torque 383 IMO, I am not brand loyal though for this I would prefer Aluminum heads, the price tag on the AFR's has held me off so far.

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Originally Posted by dave w

I posted an article several years ago "1227747 R.I.P." so I'm not going to hide my opinion that the factory 16197427 is a better computer for a performance engine on a budget.

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Can you post a link to it? I have searched for it but only thing I have seen close to it is this. If their is an advantage to wiring in a newer PCM I am willing to attempt it. I do not know the shape of the PCM in this junk 1993 K2500, but I can rob the wire harness. WOuld have to turn off the transmission controls since I have a pre electronic 700R4.

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Originally Posted by dave w

I'm also Opinionated that it's good plan to budget for tuning equipment, simply stated tuning will optimize the performance of the parts decided on.

I'm also Opinionated that an "Optimal Chip" Can Not be programmed with the information "Tell us what modifications were done". I'm so flat out Opinionated about TBI performance chips, that I BOLDLY SAY use TunerPro RT or just keep chasing tail lights like everyone else who doesn't use TunerPro RT!

dave w

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I have read TBI's info page. It has me wondering if I can get the stock injectors to do the job a little. I do not have to have the truck running today so I have the time to do this the right way. The transmission has been recently overhauled and has the corvette servo and the sonnax smart shell upgrade in it to btw.

Please disregard my comment on the AFR 195 Heads, I was mistakenly thinking about TBI head casting 193 (I don't know how I did that).

16197427 Upgrade Link: http://www.gearhead-efi.com/Fuel-Inj...out-Directions! The 1988 harness is retained by re-pinning the wiring at the computer connectors.

Define stock injectors? Stock 7.4 liter injectors flow more fuel than stock 5.7 liter injectors.

dave w

The factory ones in the truck right now, original 1988 350 tbi injectors (to my knowledge). What I have read the 7.4 ones have a hard time idling, has that been fixed?

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Originally Posted by Redtires019

The factory ones in the truck right now, original 1988 350 tbi injectors (to my knowledge). What I have read the 7.4 ones have a hard time idling, has that been fixed?

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Hmmm, there comes a point, when hear-say vs. actual tuning have to be reconciled. I really have to wonder what the hear-say information actually means when there isn't a TunerPro RT .xdl file to support the "hear-say"?

dave w

Its all like learning a new language to me, and I am barely beyond "See Spot Run" in the fuel injection world, but willing to learn, lol

My problem with tuning is I learn what you need then I don't touch it again for years until a big change comes around to necessitate a retune. I can't say I enjoy tuning. I bought the EBL, I would consider the favoured ecu of a good tuner- take that advice for whats its worth.

For heads I painted myself into the vortec corner, I have used factory (mild port w SS valves), RHS iron- nice, and now AFR- I was in a remote part of the country and due to a bad rebuild needed a set of good heads shipped in- so I put my faith in AFR to bolt on, which they did, the only problem was AFR upsold me on springs that were unnecessary. Today I would look at Edelbrock, Chad Spier, lots of choice for conventional heads- but if you buy good quality there is a resale value to them.

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Originally Posted by Kitch

375 FHP/420ft lbs FWTQ.....was that with TBI on it or a carb?

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650 holley IIRC. itnwas starting to make pressure so they figured i could go up to 750. looking back i think they kinda took my money and ran. I recall them doing pulls with all in timing @ 35 to 37 degreesa, when vortecs usually like less. as stated that was with 1.5 stamped steel rockers,probably would have made more power if they had really dialed it in. i'm sure tbi woukd have been better but i never got it tuned right on my own.