[izzy412]

I have a 68 GTO with a stock 400 350 hp engine and it appears there are only 4 exhaust manifold bolts per side.The exhaust manifolds are drilled for 6 per side.I want to replace the exhaust manifold to cylinder head gaskets and am curious on the amount of bolts thanks

 

[geeteeohguy]

If it is the stock, non HO manifolds, then there are 6 bolts per side. Be careful on the torque. The HO manifolds use less, due to the casting thickness and size. Later cylinder heads that did not come on these cars originally are sometimes not drilled or equipped for the outside bolts to hold the manifolds on. Not an issue, since the manifolds are rigid and tend not to leak. Tubing headers will need all 6 bolt holes. What is the number cast on to the center exhaust port of the heads?

 

[izzy412]

It has the number 16 cast into the center exhaust port

 

[geeteeohguy]

#16 heads are normally drilled and tapped at all 6 holes. No worries.

 

[pontiac]

when engine is cold, put a bolt in there and see if there is a tapped hole.