[Ron Landis]

Originally Posted by wovenweb

If you are looking for correct code heads for a '69 400 engine, I'm fairly certain you are looking for #16 heads which would be 72 cc's. I'm not sure which casting dates would be correct however.

I do have a set of #16 heads for sale with a casting date of C218 which would make them correct for a late 1968 car. Always an option if you are interested.

are VERY different form a '69 casting 16#...as the only 16# used in '69 model year was a pressed-in stud, low compression small-valve head that came on some two-barrel cars. A '68 16# is the large-valve, high compression screw-in stud heads. There was some confusion early on when erroneous material was printed. A '69 400 in a GTO, Firebird or GP would have had either 48# or 62# castings...depending on application. Two barrel cars are the exception. Check Eric White's book...it is accurate as far as I know. Others...not so much. Ron

[Baron Von Zeppelin]

If your #46's on the 350 - are 1973 or 1974 models - those are really some pretty decent heads and have screw-in studs. In previous flowbench tests - they performed as well as many of the 1960's performance heads.

I forget what the chamber cc is on them.
They also have hardened seats for unleaded fuel - 1972 and older mostly will not.
But have read claims of some 71-72 heads having hardened seats. idunno
1973 and newer will have them though.

If you run under 8.5 : 1 CompRatio with hardened seats - you can use 87 octane unleaded.
Believe 9.5 : 1 CR with hardened seats - is about max for 92-93 octane unleaded.

If you get into higher CompRatio's than that - you'll need race gas/aviation gas blend(s) and lead additives and things like that. It gets expensive in a street car.

The best, highest quanity, and cheapest HorsePower comes from Cubic Inches and Camshaft selection. Higher Compression Ratio is not a big factor in street engines until way way further down the line when you're trying to milk every ounce.

Another head to consider on a 400cid is the #64 from 1970 455 HO.
80'something cc's IIRC.

The higher the CompRatio - the more you have to spend on fuel.
Heads without hardened exhaust seats - an added expense to have them installed - or added expense at every refuel for lead additive.

Things to consider.

[wovenweb]

Originally Posted by Ron Landis

are VERY different form a '69 casting 16#...as the only 16# used in '69 model year was a pressed-in stud, low compression small-valve head that came on some two-barrel cars. A '68 16# is the large-valve, high compression screw-in stud heads. There was some confusion early on when erroneous material was printed. A '69 400 in a GTO, Firebird or GP would have had either 48# or 62# castings...depending on application. Two barrel cars are the exception. Check Eric White's book...it is accurate as far as I know. Others...not so much. Ron

Thanks for the clarification Ron. The NOS fenders I picked up from you/your son look great!

[69 redbird]

Gives me a lot to think about