I have a L31 (Vortec heads, you already know that though). It's going into my 86 Sierra. I want to use TBI, and I have a 2" throttle body that was used on a 4.3 Chevy boat engine. It's an actual Rochester throttle body.

So, I need some suggestions on how to get this throtte body to work with this engine. I looked at the GM Vortec to TBI intake manifold, but it doesn't look like those are 2" bores for the TBI. I'm thinking of using a carb manifold and using an adapter plate, but I'm a bit confused about what manifold ot use. Back when I was on the TBI board alot, I remember everyone saying to use a single plane over a duel plane intake. I did some searching and didn't find anyhitng on this.

What do you guys suggest I do?

 

go dual plane and buy an aftermarket carb manifold then get the tbi adapter plate for it. Something like the performer rpm or weiand stealth would be good.

 

RPM Performer and adapter plate is working well for me.

 

Thanks for the help guys!

Is it true that the factory cam in the L31 is actually a LT1 cam? Just curious.

Thanks again!

 

B-Body LT1 cam.

Get a carb intake and a holley projection adapter.

 

I looked up the specs on the LT1 cams and to me, it looks like I'd be better off sticking with the B-car cam because it makes more torque, which is what I need in a truck that's primarly used for towing.

I ordered a Perfromer RPM intake and a Pro-Jection adapter plate. Now I just gotta tune the damn thing!

 

B-Car LT1 cam=Vortec cam. They are the same thing, just the vortec uses a shorter dowl pin because it lacks an optispark.

The Iron LT1 heads=vortec heads.

Ever notice that they both have around 260 FWHP @ 4,600 rpm and 330 ft/lbs of torque at 2,800 rpm.

The F-body LT1 cam makes plenty of torque and boost HP. I have run it on a stock 350 ECM, a little more fuel pressure, and about 4* timing advance. Pulled anything I hooked to the 7,000 lbs capacity hitch. Including a 1994 chevy truck on a tandem axle trailer and an extra engine on that trailer. That was with 3.08 gears, P 255/70/R15s, 700r4 in 3rd gear, and running about 60 mph and about 2,600 rpm. Maintaining lockup was not a problem, the cruise held 60 easily, and the engine was very responsive even with total weight approaching 11,000-12,000 lbs.

 

I have a 350 cop car cam. Is it similar the these?

 

The L98 cam is similar to the LT1.

 

Unfortunatly my little project is looking to be way too expensive, especially since I still need so many parts to get my RS up and running yet again. I'm just going to put a new L05 in the Sierra. For towing my boat or the RS, it'll be plenty of power. Plus I won't have to mess with the programming.

Thanks for the help anyway!

 

I feel your pain. I am putting the GM 12514811 which is the stock L05 for Medium Duty trucks into my van. I am picking it up tommorrow night. It really doesn't cost much more if you can get ahold of one. It is being discontinued from GM. It has a forged crank, forged rods, 4 bolt mains, larger diameter pushrods, mild stock ECM compatible cam, 8.7:1 compression ratio, 210 FWHP @ 3,800, 315 ft/lbs @ 2,800, and sodium filled exhaust valves. It is rated to pull like 20,000 lbs GVW in a C60 truck.

 

Why ya changing engines for now Fast?

EDIT: nevermind, I missed your other post. Bummer

 

I can't find that engine anywhere. I found the heavy duty version, but since it makes less power, I'm not interested. I'll be fine with the light duty L05, it lasted forever in my 89 Suburban and towed good enough. The pickup is lighter anyway.