okay i got another question for ya's, I have 76's and i got some referance regaurding the cc's of my 76' heads, now a memeber on the board Nitro71455 told me that i had 78cc heads according to (http://www.atlantabuick.com/CastingNumbers.htm) then i also talked to Marco on his website: (http://www.nhra.com/tech_specs/engine/index.html#buickNHRA) did some referance on heads and they say i have 50cc heads, im not trying to cause a fight, just tring to find out what is is i have, i know i could go to the machine shop but i would rather save money. oh if its true that (69-74) 350 heads only had 1.5 exaust and the 76'-350 heads have 1.55 and the intake was the same 1.875 then i would have the better heads..............right?
Hmmm...as far as I remember the valve size is 1.55 on the earlier heads also. The 76 heads should be more like 50-52cc. The 70 heads were 48cc I believe. 78 cc would be the 455 heads. Mike
H.P. Disp. C.R. Ind. Make Model/Transmission Manifold R.R. Lifter Head cc Notes 260 350 9.00 1-2 Roch 2GV-7040143/SM 7040142/AUTO 1231381 1.55 H 48.0 1,3 285 350 9.00 1-4 Roch 4MV-7040245/SM 7040244/AUTO 1231924 1.55 H 48.0 4 315 350 10.25 1-4 Roch 4MV-7040245/SM 7040244/AUTO 1231924 1.55 H 48.0 4 350 455 10.00 1-4 Roch 4MV-7040243/SM 7040240/AUTO 1231718 1.55 H 59.5 4 360 455 10.50 1-4 Roch 4MV-7040246/ALL 1231718 1.55 H 55.5 4 370 455 10.00 1-4 Roch 4MV-7040243/SM 7040247/AUTO 1231718 1.55 H 59.5 2,4 Notes 1 Alt carb - 7040446/AUTO 2 Riviera with auto uses 7040240. 3 Carb sizes - 1686/1250 4 Carb sizes - 1375x2250/1093xAV Head H.P. Disp. Gasket Cast 260 350 .020 1233472,1240143 285 350 .020 1233472,1240143 315 350 .020 1233472,1240143 350 455 .020 1231786,1240149 360 455 .020 1231786,1240149 370 455 .020 1231786,1240149 These are the specs.....I knew I had em somewhere!
I have a 71 350 that I wanted to rebuild for replacing a '76 engine. To get the number you have listed above, I only need to change the head gasket on the '71?
If your looking to get similar power as the rated 70 engine, and increase compression, you need higher compression pistons. 71 has an actual compression around 8.2 with felpro gasket. Steel shim gasket can give a 71 around 8.45. You need a piston with a smaller dish . Some milling of block would help. As even the rated 10.2 pistons give only 9.2 compression in a standard block and heads with aftermarket head gasket.