What's the largest hydraulic roller cam that I can be sure will idle OK closed loop on a EBL'd TBI 350 with Vortec heads and either manifolds or shorty headers?

 

Here's the cams I'm currently considering:

Vortec 350 / Caprice Lt1: 191º/196º 0.414"/.428" lift on a 111º LSA.

HT383/Ramjet350/marine roller: 196º/206º 0.431"/0.451" on a 109º LSA.

1996 LT4 Corvette: 203º/210º 0.446"/0.450" on a 115ºLSA.
(.476"/.480" with 1.6:1 rockers that the LT4 engine uses)

1995-97 LT1 Camaro/Corvette: 201º/208º .447"/.459"

1987 TPI 350: 202º/206º .403"/.415" lift on a 115ºLSA

 

Remember, just because a cam is bigger....doesn't mean it performs better. It must match your engines power band.

 

I'm not to familar with TBI and tuneability with that system but those cams you are looking at are all factory TINY cams and should have no issue running closed loop idle. I've run some big cams in MAF TPI type setups closed loop with little issue but does take time to sort out the stability.

 

for my 383 TBI combo I had the stock roller cam reground to a .483 lift(w/1.6rockers) 208/218@.050" duration on 110LSA. Then I was going to have a custom chip burned.

 

99% of stock cams will go open loop if they idle very long..

 

Why idle CL?

 

Here is what I am running in a 355, Vortec. See sig. below. Idles closed loop with tuned stock ecm.


Comp Cams Extreme Energy Camshaft P/N 08-502-8
• Grind Number CS XR269HR-12
• Gross Valve Lift Intake – 0.495 Exhaust – 0.503
• Duration at 0.006 Tappet Lift Intake – 269 Exhaust – 276
• Duration at 0.05 Intake – 218 Exhaust – 224
• Lobe Separation - 112

 

What about with a heated O2?

Central IL, you're close to Decatur?

 

Looks like you've got a cam in the ballpark of LT4 HOTCAM territory.

How do you like the combo in your sig?

It sounds pretty similar to what I'm thinking about putting together (albeit for a 1992 1/2ton 2WD GMC rig which is often subjected to towing 5000lbs.)

 

Fun car to drive as a weekend cruiser. I think it is too much cam for a truck pulling 5000lbs. I would look at one of the Comp RV cams for more torque at lower RPM ranges.

 

I'm running a split pattern Comp Cam EFI series with 230/236 @ 114* lobe separation. It's in an old conventional 400ci small block Chevy that is highly modded into my 1993 Caprice wagon.

It idles very nicely at 900 rpm. It does not like 700rpm at all.
It never met a gas station it didn't like.

Yes, it requires major reprogramming

 

I ran a single pattern roller 270@.006/ 108LSA and .535" lift using 1.6:1 roller rockers. Idled great w tuning.

 

Heated 02 should be just fine, thats what I run. I get them for a 89ish fox body mustang and use em in my car...
I'm 1hr south down Rt 48..


I'm running a 256I 258E @.050 with just under .700 lift on 110 solid roller.
It idles at 550 rpm gets 22mpg and pulls like a wild man on crack.
I'm guess'n it'll run waaaaay better when I, put in the 60lb injs, 4400 converter and take out the 100% stock 89 formula 350 chip for a custom tune.

 

360 TPI. Running Howards Roller 113215-10: 110 LSA, 106 ICL Adv. 270/278; @.050 217/225; .495/.500 w/1.5 rocker. Using 1.6 rockers at .528/.533. Idles at 750 in gear, 15-16 in Hg., stock converter. Great street cam. Rough idle and very flat torque curve and pulls hard everywhere. Very minor tune changes from 204/214 @ .050. This is a mild cam with TPI compared to what others are running on this forum. Easily tunable.

 

sbc 400 Lt1 intake-TPI 730 ECM, hydr roller 230/236@0.50 .510/520 with 1.50 LSA 112 idle 650 - no problem

 

Stock 4" bore 350 with 280/288 @ .006, 226/234 @.050, 565/565 with a 1.6 rocker, Idel is rough but I keep it @ 750rpm, makes 14-15 in Hg.

 

I'm running basically a baby ZZ4 and it idled smooth and steady once it warms up.