matt506

Does anyone know info on A heads? From some studying I believe they are one year only and a very hood breathing heads. Anything else to know? Worth?

joe_padavano

A heads are 1965 only. They use 3/8" studs for the rocker arms as opposed to the 5/16" bolts on all subsequent Olds heads. The rocker pivot blocks/bridges are unique as a result. All BBO heads except for the J heads are probably within 5% or so of each other as far as flow. This applies to the as-cast condition. Keep in mind that there is manufacturing tolerance on the port sizes and shapes, and the published flow data you find on line is based on a very small sample size that is not really statistically valid to cover these tolerances. Most A head castings do not have the bumps in the exhaust ports for the A.I.R. system.

2blu442

1965 Big block, used on the 400 and 425. Most don't have the hump cast into the exhaust ports which is thought to help them breath better without having that ground out. If they are a factory pair one will have the application code stamped into the end of it. If that code starts with a letter V they're from a 442. That would make a difference in price, but if they are from a 425 then the price would be similar to other big block heads except the J's.