I see several different heads for the 455; D, E, F, Ga, etc. Is there a list showing the specs of each head and also the application? Prices for these are anywhere from dirt cheap to in the stratosphere and I'd like to learn about the different variations.

 

You could start here: Olds FAQ - Heads

 

D, F, and H heads were only used on W30 cars and 68-68 H/Os. They are stratospheric because a correctly restored car must have them. The loss in value without those correct heads is probably $10K or more. Performance-wise, with the exception of J heads, all big block Olds heads flow within about 5% or better of each other, assuming the same size valves. C heads are the most common (other than J) because they were used for three model years. A head have 3/8" rocker stud threads; all others have 5/16" bolts. All heads from model year 1971-up have induction hardened valve seats. This is not an insert, just a thin surface hardening that is ground off the first time you have the valves done. Some heads from industrial motors intended to run on natural gas (that didn't have lead) did come with real seat inserts. Heads that used valve rotators (1971-later) have deep spring pockets to make up for the rotator thickness.

 

Joe, one more thing on the A heads is that most don't have the bump for the A.I.R. cast into the exhaust port. I've run into a couple people who prefer them so they don't need to have that bump ground off.

 

Correct, John. I left that out because I didn't want to start the whole "well SOME A heads came with A.I.R. bumps" detour.

 

Understand!