firsttimeoldsowner

Hi ya'll doing sorry been awhile since I posted on here, well I just read the book "How TO Build Max-Performance Oldsmobile V-8 by Bill Trovato" and he said the 7A heads are from a 307 engine. But everything I've read on the interweb says 7A are 350 heads with a 64cc chamber. Now just to clarify I want to get 350 hp to 400 hp on a very tight budget. That's why ordered this book but all it did was confuse me more so any help or if someone can give a course of action or which way to go to achieve the desired results would be great as in what cam should I get or should I go with a hei setup or stay stock on ignition things like that would be great. And thanks again for the all the input.

brownbomber77

The 7A you're looking for has the "A" as a subscript down to the right of the "7". They were on 1972 350's. The 7A's from the 307's have the same size "A" as the number 7. The "A" denotes hardened valve seats in Oldsmobile heads. I don't know of anyone who has sunk a seat like Chevys do... If you're looking for higher compression on a smog engine, try 330 heads, #3, #4. They have smaller combustion chambers than the 350 heads.

joe_padavano

Yes, an unfortunate source of confusion. Note that the 1972 heads are 7A, whereas the 1980s heads are 7A. The casting numbers above the center exhaust ports are also different. The 1971-72 heads are casting number 409147. The 307 heads are 0142

Another bit of Olds misinformation that refuses to die. The #7 heads (without the "A") from 1971 have hardened seats, as do the #8 heads from 1973-76, the "G" heads from 1971, and the "J" heads from 1973-76.

The chambers on all SBO heads prior to 1973 are within a couple of cc of each other. You'll never feel the difference. The published numbers are NHRA blueprint numbers, not the as-cast number that you'll measure if you actually CC a given head. More to the point, if the head has ever had ANY work done to it, all bets are off on the actual CCs.

brownbomber77

Noted

Octania

" Note that the 1972 heads are 7A, whereas the 1980s heads are 7A. The casting numbers above the center exhaust ports are also different. The 1971-72 heads are casting number 409147. The 307 heads are 0142"

in the earlier days of the internet, we had text. ASCII characters, period. In order to distinguish the two significantly different types of cylinder head with similar main casting ID, I adopted the practice of writing "7a" for the 1972 version with the small [and subscript] upper case "A" - leaving "7A" to represent pretty much exactly as shown on the head the later smog era roller cam 307 head ID.

Now that we can make tiny upper case [and nearly subscripted] "A" characters like seen above, we should just do that. When in doubt, include the casting number as well. With the main ID and the casting number, the part should be pegged.

The 7a/7A head confusion is but one example.

There are L & R "W" exhaust manifolds
Two different "H" exhaust manifolds?
two distinctly different "KB" crank pulleys
two different "J" intakes....
plus factory casting ID typos which I have documented. See the INTAKES thread here for an example.

firsttimeoldsowner

Awesome thanks now about the question I have..... And thanks again everybody!!!

joe_padavano

And we had to walk five miles to and from school, in the snow, uphill BOTH ways...