I have an 86 3rd gen that I pulled a 2.8 with a 5 speed out of and am replacing it with a 92 350 that I took out of my old 2wd truck. The motor has centerbolt style heads and is an efi. I want to know if old stlye heads match up bolt pattern wise and if the cc chamber would be right, or if I would need to do any machine work. Also what kind of cam is in my engine, is it mechanical or hydraulic? And depending on which one can I switch as long as all lifters and misc. parts work in conjuction with the new style cam. Any help would be great. Thanks, Shawn

 

Ok, so heres what I have been told. I can use pre 86 heads as long as I switch the manifold also.

 

Welcome aboard thirdgen.org.

Need to clarify some terms here.

'87-up Gen I small block Chevys had the center two intake mount bolt holes on each side at 72 degrees instead of 90 degrees like all the other bolts as had been done from 1955-1986. The valve covers went from 4 perimeter bolts to 4 center bolts at the same time. Exception is the Corvette L98 with aluminum heads maintained all intake mount bolts at 90 degrees.

In 1988, the factory came up with something called "swirl port" heads that were used on all TBI engines. The intake port has a "wall" that induces a swirl as the air/fuel enters the cylinder. This swirl promotes good combustion, which enhances economy and power and reduces emissions, at the cost of good high-lift and high-RPM flow. The chambers/intake valves for these heads were 58cc/1.84" for 305 engines, and 64cc/1.94" for 350 engines. They were used on trucks until 1995.

You can use an '86-earlier intake manifold with these heads if you modify the center two intake mount bolt holes on each side. Basically elongate them so the bolt will go through at 72 degrees. '87-up intake manifolds are also available in limited types.

f-body V8 engines had hydraulic roller lifters from 1987-up. Truck V8's generally didn't get roller lifters, but the older/cheaper flat tappet hydraulic lifters. The 350 block would be cast with the provisions for the roller lifters, but sometimes were not final machined for them if the engine was going into a truck. TBI engine cams were tailored for low RPM torque and fuel economy.

 

this is all true. my outer holes are 90 and the centers are 72 like you say. What i was told by the machine shop that i want to bring my block to was that an earlier set of heads(pre 86, he told me even earlier) would bolt onto my 92 block, i would have to put pre 86 intake to match the heads. ive been reading that the tbi heads i have are not worth working on. i believe ive seen you say that, ive also printed off your v6 to v8 swap, very helpful thank you. here is my plan. my 92 block, forged flat tops 30 over. stock rods and crank. aftermarket pre 86 heads with 67 cc 2.02 1.60, victor manifold, hydraulic cam with mild lift and duration, flat tappet lifters,roller timing chain, mallory hyfire 6al ignition, roller tip rockers, holley street avenger 670 cfm. thats what im thinking. i might add nitrous later, but i know ill have to put in different rods and possibly a new crank. i think this will all work together. thanks for looking.

 

Except the Victor manifold (I assume you mean Victor Jr.). It starts making power at about 3500 RPMs. A mild cam will run out of breath just after the intake starts working. A Performer RPM will be just fine for an engine that's streetable.

You don't necessarily have to replace the rods and crank for nitrous. Just depends upon how hard you spray it. If you're spraying it hard enough to need a forged crank, you should be building a nitrous motor from the start, anyway.

 

i guess i could just go with an intake and cam kit from edelbrock. as for the nitrous, it would be just for a little extra giddy up in the camaros step, hahaha. you sure do try and answer alot of questions and help people with ideas, really appreciate it. thanks even though its not gonna be alot of nitrous, im still gonna need the anti ballooning stall converter right? 700r4 tranny, 30 spline

 

Intake from Edelbrock, fine.

Cam from Edelbrock, a waste of performance $'s.

You'd need to be making quite a bit of power to need an anti-ballooning TC, although it wouldn't hurt anything.