I came across an interesting bit of spec info on the 300 cylinder heads that may be useful to anybody building up their smallblocks. I was under the impression that all cast iron 300 cylinder heads were the same, just different years. Not so, as I just discovered. Here's what I saw. 1965 casting #1366379, 1374870 = 51.12 cc chambers 1966 + 1967 casting # 1376329 = 54.9 cc chambers As far as I know, Buick used basically the same piston design from 65-67, so increasing the chamber size may have been their way to lower the compression ratio from 10.25 in the 250hp '65 engines to 9.0 in 210hp engines. Beside it's value when play Trivial Pursuit Buick Edition, the info may be worth something if you're building an "off-road" engine. :Smarty:
So are you suggesting that if I slap a set of '65 heads on my '66 300 (which already has a '65 4bbl intake), I'll gain 40 hp? That seems like a pretty cheap way to put a little bit more "oomph" into my engine.
smallblock combustion chambers Oh, at least 40hp, Grayta!!!!! Now, if I can just convince you to replace your stock flexplate with a plastic one, I can show you how to pick up another 40. Just kidding of course. I have no idea what the performance improvement will be. I'd assume something much more conservative than 40, however. You did get me to thinking about the piston-to-valve clearance thing. What kind of cam do you run in the motor? Mark
(laughing) Everyone knows that plastic flexplates are only good for a 30hp boost, duh!!! Bone stock. Do you think there might be a clearance issue?
smallblock combustion chambers Having a sense of humor is a pre-requisite for becoming a Buick fan. I'm pretty sure the cam specs for the '65 2-bbl engine are the same for the later models. The '64 had a bit more lift and it had even smaller chambers than the '65. No, I was thinking that if you had a performance cam, it would be worth checking. Have you read about the new cyro-magnetic rod bolts? Gotta get a set for my new motor!
