1974 455 Oldsmobile jetboat engine

[cyclops2]

Frosty is right on about the people who ALWAYS true up the heads.

If you can not find the TRUE PROBLEM. True up the heads. Solves everything.

Good engine shops know that problem like breathing.

[Frosty]

Its the manifold that now needs machining to fit between the heads. Or the head face of the manifold. If you keep skimming the heads with a V configeration the heads are getting closer together and there will be no room for the manifild to fit in between the heads. This results in all kinds of leaks including water into the engine above the cam followers ( lifters in USA).

Its a mathamatical problem,--if the head has had a total of say 10 thou removed then the equivelent of 10thou at 45 degrees need removing of the manifiold face, probably 5 thou --I think.

If I remeber correctly 6 thou is the max to remove off a V head before uncovering this problem.

[cyclops2]

When racing Octane was Sunoco unblended at the gas pumps. Everybody milled the heads. 50 years ago machine shops used Plastiguage to check the seating angles of the manifold inlets to the cylinder head angles. Some used special thick gaskets. Silicone RTV might do the job. ...........But at your 200 PSI ?

NAHH

[C Skip R]

Don't know the answer to your issue but had a jet boat in 1974 that had the same engine in it. As I remember it was a goldish metalflake color. Have alot of memories in it during those times. Don't remember the manfacturer name.

[NorCal]

I acquired an older direct drive with a 455 olds and just noticed relief cuts on the exhaust flange. Is this normal? A metal straight edge indicates that everything is flush but I'm a bit confused. Also one side is a Glenwood the other is from Hardin. Character right?