I've come across a set of high compresson pistons out of a pooched 69 350 .I have a 79 350 in good shape ,would there be any problem putting these pistons in the 79 block ? The 79 block has been recently over hauled and it also has a new crank and modified oiling system ,this is why I want to go with this block .Would the final compresson ratio be low useing the 79 heads ? I know it would be better to use earlier heads but I want to keep the engine pump gas friendly Any advice would be appreciated .Ihave checked atlanta buik and there info only goes back to 74 .Also how was the compresson ratio lowered ,was it deeper dished pistons or larger cc ed heads or both ? Also where can I find more info on the late 70's 350-455 engines Later Z28 455 Camaro
455 were only made up until 75 or 76. 350's ran until 1980. the compression differences were mainly in the dish of the pistons. the head CC's differed slightly in each year, but not by much. i don't have exact numbers, but 79 heads are in the low 50's while the earlier heads are around the high 40's...not much difference. and if the pistons are from a 69 engine, they shouldn't be 10.25:1. only high comp (SP coded) 1970 motors had those, the 69's were a bit lower.
Actually, the 68-69 350-4/400/430 engines are listed at 10.25-1. According to Steven L. Dove anyway... My 68 Facts and Features manual also states it as 10.25-1.
you sure? i think the 400 had 10.25:1, but i thought the 68 and 69 350's had the same compression as the lower hp 70 motor (9:1, i believe?)
Well, I'm just giving you the #'s from the Guide to Buick Performance Engines, and my 68 Facts/Figures book. The 68 350-2 was a low compression motor, 9-1.
I am looking at a 69 Buick Features Book under the engine specifications section and it showes the 350-2 has 9.0 compression, the 350-4 has 10.25 compression, the 400-4 has 10.25 compression, and the 430-4 has 10.25 compression also. I hope this helps. Ken
69 pistons in 79 block Thanks for all the great advice .What am i looking at for final compresson ratio ?The 79 block has not been milled .I realise it would be better to use the 69 heads as well but I want a bit of economy as well ,the gas prices have gone through the roof here. Later and if you can't have economy you might as well have power.
Thats right the 69 did have 10.25 to 1 with a 4 barrel in gs's. ALso youll be better off with your 1979 heads because they have slightly larger valves than the earlier heads. 1.55 exaust valve instead of 1.5, and im not sure if they used 1.92 intake or if it was 1.875 like the earlier head. Just take a few thousands of the faces of them and theyll be the same CC as the earlier heads.....maybe .010 or .020. I wouldnt go to much more with high comp pistons if your gonna be running pump gas.
One more short dity , what were the cam profiles of the 69 as compared to the 79 ? Ithought I read some where that the cam profiles stayed the same all the way through the 350 engine run .I'm taiking stock engines not GS or ram air engines . Please bear with me as I try and sort this stuff out .As I tell my apprentices there is no such thing as a stupid question just stupid answers . Later
