Hi Guys Need your help. I have a 1992 Camaro z28 with the 305 tpi. I put a L98 out of a 90 corvette in the car and used the vette aluminum heads. I tried to bolt up the tpi from the 305 I had and the ports matched up but the bolt holes didnt. I had to grind the manifold bolt holes longer to get the bolts to go into the heads. Why did this happen? are the 350 (5.7) and the 305 (5.0) manifolds different in some way ? Thanks !

 

The corvette manifold has a rear coolant crosover for better cooling. The bolt pattern of the Y l98 is 55-86 . The Y-manifold also has the reag egr feed as well as the center exhauset feed but the 113s do not have a passage other than the rear.

 

Ok is the 305 tpi manifold useable on the 350 ? and Why do the bolt holes not line up? ( i had to elongate the holes )

 

then why do the the manifold bolt holes not line up. The 305 tpi manifold is use able on the 350 Right?

 

Because cast iron SBC heads made '87+ have a different bolt angle on the 4 center bolts to that used on the earlier heads.

The Vette alum heads only ever used the old style pattern

 

There is a Echo in here lol

 

So by making the holes larger I can use the 305 TPI intake?

 

just like the aftermarket intakes where one version fits both style heads

You may need a large washer under the bolt head on those 4 holes to spread the weight correctly for gasket clamping
Note the aftermarket version has 2 different flats machined to suit the stock bolt head

 

thanks for the pic. That really helps out.