does any one know if there is a difference between the 1986 and 1987 TPI manifold base?Is there a difference in the bolt pattern or the bolt angle or is there any at all?Thanks in advance

 

Cant really speak for the F-body bases but I kow that the 85-early 86 corvette base that went with cast heads was the same for both years. As soon as they went to aluminum heads the center bolt angles changed when bolting up the heads.

 

Yes, the 86 intake has the older style intake bolt pattern, while the 87+ has the four middle holes at a different angle.

 

I have the alluminum corvette L-98 heads,also used on the zz-4 engine.When i bought them i had to by a 1986 base,but id like to port my 1987 base and put it back on.Im also looking for an aftermarket base,whatever is cheapest

 

I have those heads too. Definitely go with the aftermarket base. You can only port the stock base so far, and the aftermarket base is still bigger.

 

I would love to get an aftermarket base but at the time they are too expensive

 

My 350 engine has a differnet angle holes because I had to modify the stock intake holes to a steeper angle. It was really easy with a dremel tool too. The stock intake I have has holes that were more straight down before the modfication. I ported it and polished the crap out of it inside. I noticed a better throttle response and I'd say gained a few upper rpm's too. (Along with porting and polishing the plenum, and polishing the throttle body.)