Trying to finish up swapping a 5.7 vortec engine (from a 99 van) into an 89 firebird. I have used the TPI/vortec baseplate conversion which worked great. Almost ready to drop the engine into the car, when I can not bolt up the drivers side exhaust manifold. The factory 5.7 TPI heads have a second bolt pattern for the manifold, due to the rear port on the factory manifolds. The Vortec heads do not have this extra wide hole, therefore the factory manifolds can not bolt up.

Customer would like to retain the AIR injection system and has previously had a new Y pipe and cat back built for the factory manifolds.

So my question... is there a direct replacement header or manifold that retains the AIR system and will bolt up to the Vortec cylinder heads?

Thanks.

 

Find a set of 87-92 f body manifolds and you will be good to go if ur trying to retain the the factory air bologna

 

The factory "f body" TPI manifolds are my problem. They will not bolt up to the vortec heads due to the drivers side manifold utilizing the extra wide 7th hole on the cylinder head (which the vortec heads do not have).

Either way, I installed a set of hooker 2055's with the air tubes.

 

I ran into that problem with Vortec heads years ago and the extra bolthole with the TPI manifolds so i ran headers also.

 

in case someone else stumbles upon this, many have installed the factory exhaust manifolds without the rear most bolt with no leaks, myself included.

The right side was the issue though. The location of the down pipe on that one is where the normal bolt hole is. The left side allows all the bolts to be used.

 

Not all Vortec heads lack the 7th bolt hole. Also LT1 manifolds have enough meat on the flange to drill a hole for the Vortec pattern. Would require slightly revising the exhaust and using the LT1 exhaust flanges but the LT1 manifolds flow much better and match the Vortec exhaust ports better. The manifolds also have AIR injection provisions.