Does anyone know if the standard piston in a 70 big block (454) is a flat top or a dome?    The supposed compression is 10.25:1, it also has the "290" closed chamber heads.

Thanks

With closed chamber heads, it takes a flat top piston to achieve 10:1 compression. 

Incidentally, for those with dished pistons, use of closed chamber heads will bring the compression up to about 9:1, which is a big improvement without completely rebuilding an engine.

Larry

I have the engine down to the short block and it has flat tops with two small valve reliefs and the closed chamber 100.9 cc heads. I dont think its any where near 10.2:1, I believe it's more like 9.2-9.5:1. I used the compression calculator on the internet and thats what it came up with. So thats the reason for my initial question.................is the standard piston flat or domed.................plus the shifter plate says 10.25:1 !!!!   so it has to be right   

Sorry for the delay.  I had a couple days R&R. 

Everything I can find says the 70 454 had flat top pistons and a closed chamber.  Chevrolet determined that amounted to 10.25:1 compression.  On rare occasions, they were known to exaggerate, so your calculations could very well be closer to correct.  There is a lot of variation in quench area and deck height, so you could both be fairly close.

Larry

Hey Larry,

Thanks for your research.........I did some myself and several opinions were they were a small dome about 10 cc. If I plug that in to the compression calculator with the closed chamber, a gasket bore size of 4.370 and a quench of .039 its 10.2:1. So an engine builder friend of mine has three sets of the correct pistons and agreed to sell me a set.
I just feel better with it being "right"Fairlane5142008-04-10 20:07:54