Cam help for TBI 350

**tayto** · 11-13-2014

Hey guys, I have a project that has basically been sitting for 2 years and only been driven a handful of times since I got it running 3 summers ago. Basically had an engine built 6 years ago, and when I went to install it a few years ago I figured I'd get it dyno'd. While it made decent power (375 FWHP/420 FWTQ) when we went to drain the coolant out of the block we discovered the drains were blocked solid. Tear down was recommended and we found the coolant passages caked with rock hard sediment. I removed a ziplock sandwich bag worth of crap AFTER the new machine shop hot tanked the block! Also found bearing clearances were tighter than normal so ended up getting the block re-rebuilt. I'm not saying the machine shop tricked me, but they definitely didn't give me "good" advice. Had I know how bad the engine had been rebuilt in the first place, I probably would have just walked on the project and just been done with it, but instead I just kept spending. Live and learn. Anyway, this is what I have and hopefully it can be made better so I can get the car tuned and enjoy it.

350 2-bolt block bored .030"
Sealed Power flat top pistons (H345NP) with 5cc valve reliefs
Vortec heads, modified for high lift cam (~.570")
CompCams 07-466-9 218/224 @ .050 113* LSA .570/.56
stamped steel 1.6 rockers and stock length pushrods
CompCams BeeHive springs (26918)
stock OEM roller lifters
Edelbrock Performer RPM intake with coolant plumbed to run under TBI (per rbob from DynamicEFI)
454 TBI, with "cop car" injectors running @ 30 psi with VRFPR
Tri-Y headers (1 5/8") and 2 1/2" duals with X pipe, full tail pipes

I personally think the cam is to big for my application (4200 lbs B-body). Another issue I had was not getting proper oiling at idle to all rockers. It seemed the outside corner cylinders would not oil correctly. Not sure if this is lifter, cam or cam bearing related. I have good oil pressure (~40-60 psi @ idle depending temperature) When I first manually primed the engine a few years ago I got good oil flow to all rockers, so maybe it is distributor related as I used a gutted distributor to prime engine... I am very close to just selling the car and getting what I can for it, it does run right now so I am have on the fence about seeing if I can just get it tuned and call it a day. I no longer have a garage or place to work so I would have to rent something to do any more. Any suggestions appreciated.

**Fast355** · 11-13-2014

Originally Posted by tayto

Hey guys, I have a project that has basically been sitting for 2 years and only been driven a handful of times since I got it running 3 summers ago. Basically had an engine built 6 years ago, and when I went to install it a few years ago I figured I'd get it dyno'd. While it made decent power (375 FWHP/420 FWTQ) when we went to drain the coolant out of the block we discovered the drains were blocked solid. Tear down was recommended and we found the coolant passages caked with rock hard sediment. I removed a ziplock sandwich bag worth of crap AFTER the new machine shop hot tanked the block! Also found bearing clearances were tighter than normal so ended up getting the block re-rebuilt. I'm not saying the machine shop tricked me, but they definitely didn't give me "good" advice. Had I know how bad the engine had been rebuilt in the first place, I probably would have just walked on the project and just been done with it, but instead I just kept spending. Live and learn. Anyway, this is what I have and hopefully it can be made better so I can get the car tuned and enjoy it.

350 2-bolt block bored .030"
Sealed Power flat top pistons (H345NP) with 5cc valve reliefs
Vortec heads, modified for high lift cam (~.570")
CompCams 07-466-9 218/224 @ .050 113* LSA .570/.56
stamped steel 1.6 rockers and stock length pushrods
CompCams BeeHive springs (26918)
stock OEM roller lifters
Edelbrock Performer RPM intake with coolant plumbed to run under TBI (per rbob from DynamicEFI)
454 TBI, with "cop car" injectors running @ 30 psi with VRFPR
Tri-Y headers (1 5/8") and 2 1/2" duals with X pipe, full tail pipes

I personally think the cam is to big for my application (4200 lbs B-body). Another issue I had was not getting proper oiling at idle to all rockers. It seemed the outside corner cylinders would not oil correctly. Not sure if this is lifter, cam or cam bearing related. I have good oil pressure (~40-60 psi @ idle depending temperature) When I first manually primed the engine a few years ago I got good oil flow to all rockers, so maybe it is distributor related as I used a gutted distributor to prime engine... I am very close to just selling the car and getting what I can for it, it does run right now so I am have on the fence about seeing if I can just get it tuned and call it a day. I no longer have a garage or place to work so I would have to rent something to do any more. Any suggestions appreciated.

The cam is not too big with the right combination of compression, intake, exhaust, stall speed and gear ratio. I ran a 232/240* @ .050 roller cam in a 10.5:1 383 with modified SLP TPI setup in my 5,000 lbs G20 van for while. A little sluggish off-idle, but it came on strong through the midrange and screamed on the top-end. I was only running a L35 S10 converter in the 4L60E and 3.08 gears in the rear. I could cruise 80+ mph locked up in overdrive all day long at 2,000 rpm.

I am not a fan of stamped steel rockers, especially with a cam of that lift.

With that setup I would run a 2,600-2,800 rpm stall torque converter and 4.10s to push your heavy beast off the line.

The cam in my 97 Express van is 215/220 @ .050 on a 114* LSA and I am running it on the stock 2,200 rpm 4L80E converter and only have 3.73s in the rear. I have had over 7,000 lbs hanging on the trailer hitch of the ~6,000 lbs conversion van and never felt the cam was "too big".

**tayto** · 11-14-2014

I am sitting around 10:1 compression, and a quench in the .060" range which is kind of disappointing. What would you recommend for rocker arms? Just the roller tip ones? I do not want to spend $500 on a roller rocker setup. Currently have 3.42s behind a 700R4 that I rebuilt with one of Dana's rebuild kits. I have Edge 9.5" converter that stalls at 2600 rpm. Seriously think I am just going to leave it as is and see if I can find someone to tune it. I don't mind tweaking minour things myself but over the past few years have virtually lost interested in this wanting to learn how to tune and the "car" hobby in general. Any other suggestions Fast would be great, I know you've done lots of TBI setups...

**Fast355** · 11-14-2014

Originally Posted by tayto

I am sitting around 10:1 compression, and a quench in the .060" range which is kind of disappointing. What would you recommend for rocker arms? Just the roller tip ones? I do not want to spend $500 on a roller rocker setup. Currently have 3.42s behind a 700R4 that I rebuilt with one of Dana's rebuild kits. I have Edge 9.5" converter that stalls at 2600 rpm. Seriously think I am just going to leave it as is and see if I can find someone to tune it. I don't mind tweaking minour things myself but over the past few years have virtually lost interested in this wanting to learn how to tune and the "car" hobby in general. Any other suggestions Fast would be great, I know you've done lots of TBI setups...

.060" quench is not helping combustion efficiency or detonation resistance at all.

Just the roller tip is a waste of good money IMO. I would go with the comp ultra pro magnum self aligning. The fulcrum is where most of the friction losses occur and the stamped steel rockers deflect under high lift/high spring loading. You said you didn't want a $500 rocker setup, the ProMagnums are $339.00 shipped through Jegs. My old recomendation would have been the Crane Gold narrow body LT4 style rockers, but since Crane relaunched they believe their stuff is made of silver, gold and platinum and pricing reflects it. I like the Pro Magnums because they are steel and will not fatigue as easily as an aluminum rocker.

http://www.jegs.com/i/COMP+Cams/249/1618-16/10002/-1

I am not a fan of Edge converters although I have not run one. I watched a 2,800 Edge that was spec'd by Andre himself slow down a 2003ish Dodge Dakota with a mildly built up 4.7. I also saw a cammed 5.7 Hemi Ram held back by an Edge, switch to an APS with the same stall speed rating and pickup 3 tenths in the 1/8! Depending on the stalll speed in your setup, it may need a restall. Not quite sure Andres logic to use a 9.5" converter for only a 2,600 stall. The factory S10 converter stalls 2,600-2,800 behind a modestly built 350 and only cost $120 remanufactured. Had one in the 99 Suburban with a LT1 cam, cold air intake, headers, dual exhaust and HP Tuners tune. For being a 5,200 lbs truck it had some get up and go!

**Fast355** · 11-14-2014

As for the cam, you could try degreeing it on a 107* ICL rather than a 109*, this would give you 6* total advance and more off-idle and midrange torque from the earlier valve timing. That being said it will raise your dynamic compression ratio. Another way to gain power across the board would be with a pair of rubber embossed steel shim head gaskets. If you are running a piston that is .025" in the hole, and you use a .016" compressed rubber embossed steel shim head gasket you will be at .041" quench rather than .060". You will gain roughly 1/2 point of compression. With good quench you will have less of a tendency to detonate and the vortec head can work more efficiently in respect to swirl and tumble. If you happened to run into detonation with the higher compression ratio, you could retard the cam to a 113* ICL and lower your dynamic compression ratio some.

**Fast355** · 11-14-2014

What specifically is wrong with the car that you would think the cam is too big??? Just doesn't have the take-off you would expect? Runs poorly? If it has not been tuned correctly it could be mostly tune. I really don't see any particular mis-match in your combination other than quench. I am not a fan of stamped steel rockers or Edge converters but I doubt they are noticeably hurting your setup, just not much of an improvement over stock parts.

Do you have a .BIN file and datalog for the car? Is this car running the EBL?

**tayto** · 11-17-2014

Cam has been advanced 4* as per the original builder, so I believe this is already 6* total advance? I thought running over 10:1 on vortec heads was not a good idea unless you're running over 91 octane? anything over 91 in Canada isn't the easiest thing to come by. Currently running 91, noticed a huge decrease in knock counts since going down 2 steps colder on my plugs. Yes running EBL. I think it mainly needs to be tuned, I just don't have the know-how or interest anymore. No one locally seems to want to tune it. I tried Dave at Old school EFI since he is only about a 6 hour drive from me, but it seemed like to hot of a setup for him. BIN and most recent log from this summer attached.

Just a note on my injectors, they are cop car injectors and I got them flowed at witchhunter. I got him to flow them @ 30 psi they came out to 113 lbs/hr, roughly 74 lbs/hr @ 13 psi... Currently running them @ 30 psi and setup the bin accordingly. wondering if this is to high maybe need to drop it down a few psi?

**tayto** · 11-18-2014

fast, was looking at those rockers. i will have to check the studs in the heads not sure if they are 3/8 or smaller...

**mytmouz** · 11-18-2014

Stock lifters with that lift cam could be your oiling issue. The oil holes on the side of the lifter body can clear the lifter bore. Comp (and others) sell a lifter specifically to address this...

**tayto** · 11-19-2014

Yes I have heard of this and is most likely why I am having oiling issues. Crane makes these "long travel" lifters and they are in tune of of $700 for a set. This is one of the reason I was debating going to a smaller (lift wise) cam...

**mytmouz** · 11-19-2014

Comp cams brand is much cheaper than that...

**tayto** · 11-19-2014

p/n?

**mytmouz** · 11-19-2014

OK, reread everything. The long travel lifters you are referring to are for a small base circle camshaft. This keeps them from dropping out of the lifter bore. Comp doesn't offer a cam shaft with a base circle small enough to allow that to happen in the OE hydraulic roller line up. Comp makes 2 lifter sets, a OE style p/n 850-16 same as what you have, and a 'short travel" p/n 875-016. Those are what I went with as recommended by Comps Tech line...

**Fast355** · 11-20-2014

Originally Posted by tayto

Cam has been advanced 4* as per the original builder, so I believe this is already 6* total advance? I thought running over 10:1 on vortec heads was not a good idea unless you're running over 91 octane? anything over 91 in Canada isn't the easiest thing to come by. Currently running 91, noticed a huge decrease in knock counts since going down 2 steps colder on my plugs. Yes running EBL. I think it mainly needs to be tuned, I just don't have the know-how or interest anymore. No one locally seems to want to tune it. I tried Dave at Old school EFI since he is only about a 6 hour drive from me, but it seemed like to hot of a setup for him. BIN and most recent log from this summer attached.

Just a note on my injectors, they are cop car injectors and I got them flowed at witchhunter. I got him to flow them @ 30 psi they came out to 113 lbs/hr, roughly 74 lbs/hr @ 13 psi... Currently running them @ 30 psi and setup the bin accordingly. wondering if this is to high maybe need to drop it down a few psi?

I need to dig out my tuning laptop and download these and look at them. Have been sick and haven't felt like messing with it much.

113 lb/hr x2 /.45 x .85 = 426 hp worth of fuel

If you are under 75% duty cycle at WOT you can lower the pressure about 4 psi and see where you end up. Honestly if your injectors are 74# at 13 psi and increase to 113# @ 30 psi they are exactly where the math would show. Math actually shows 112.4 lb/hr. A 68# injector rated at 11 psi should also flow right at 74 lb/hr @ 13 psi.

Now this is where experience and math comes in. The setup you have should be good for about 400 hp. At .45 lb/hr/hp bsfc you need 180 lb/hr of fuel flow. At 85% duty cycle you need 212 lb/hr of fuel flow from the injectors. With 2 injectors, each injector needs to flow 106 lb/hr. With a base flow of 74 lb/hr @ 13 psi and working the pressure formula backwards you need 26.67 psi fuel pressure to support 400 HP. If you end up a little over 85% DC it won't be the end of the world.