Are mid 90's truck TBI motors compatable with a 91 tune port setup? My step son is in trade school and needs a project. I can get a 5.7 truck core for $150 have him rebuild it, and use it to do a 5.0 to 5.7 swap in my 91. Are there any pit falls in this plan? Thanks for any input.

 

all SBCs will be a direct swap as far as bolting up and acessories. after 87 gm used the one piece crank seal and the flew plate or flywheel would have to match the crank. you have to use the prom and/or the ecm for the 350 or swap all your induction parts to it.

 

Right, it's "compatible" in that sense; but a truck motor has the crappy heads with the "swirl port" obstructions, so it will produce far less HP as compared to the TPI heads. Also, the block will not be fully equipped for the roller cam setup in your 91 TPI motor, which is definitely worth keeping; but you may be able to drill & tap the necessary holes in the block for it. Either of those 2 things would create a massive downgrade from the 91 TPI motor.

Look at the block and see if it has all the roller provisions cast into it; by 91, most truck motors did; if so, get it, use the block, throw the heads away. The casting # on the block should tell if it has that. You can look up casting numbers at www.mortec.com Get a set of TPI 350 (L98) heads, a good place to look is the classifieds on this site. That will give you a good project that will enhance the car rather than downgrading it.

 

I figured the heads would be junk, and was hoping to locate a late enough block that would have a roller in it, but if the later flat tappet can be converted that might be good exprience for my son drilling them out. I'm upping the ante now............ One yard has a truck vortech 5.7 out of a flood recovery for $400. It was still running when it was taken out. I know about the base manifold that will have to be changed, and have been keeping up on the Mike Crews saga Are these the same vortech heads members buy, and is there any other problems going this way. Thanks to all who have helped so far.

 

Those are the same Vortec heads everybody buys. Scoggins-Dickey sell the TPI manifold for vortec heads. I am sure there are other places you can get the base also. That is the way to go, if you can. Get the Vortec 350.:rockon:

 

AFAIK SDPC is the only place to get that base, it's their own product.

But that's another reasonable possibility if you can put together that parts combo.

 

I'm back from the auto parts recycler (I guess junk yard isn't all that politically correct these days),with two cores, 88 truck 5.7 and 98 vortec 5.7. I pulled the fly wheel to get the vortec on the motor stand and I see that it looks to be externally balanced. When did this start happening? Is my 91 5.0 balanced that way? If I get a t56 from a 4th gen, with a flywheel, I should be covered right? Or will that flex plate work with my 700r4 should I leave it? I got both long blocks, and a roller cam set up from a low mileage vortec for $535. Let the FUN begin!