what are these pistons???

the numbers are 3671052 and 3671053.
I cannot find those numbers anywhere to determine what exactly they are.....
my guess is that they are standard 1972 400 pistons, which would mean that I have a 8.2 compression ratio with 452 heads?????

This is what I found:

V8 400
6.6 L
4.342(IN)
110.3(MM)

1972-80 years

8.0 comp ratio

Flat head.

Comp. Ht. 1.812
Pin Dia..1.094 Offset

Silvolite pistons

isn't 8:1 a bit low for a .509 cam????????????!!!!!!!!!!!!!!

I am not sure I don't know how cam size effects compression. I would think your heads and valve size would be more important to keep up with it.

Yeah thats pretty low for that cam. It likes alot of compression, like 10:1 and aloose converter with steep gears.

it's actually worse than you think..Those factory pistons+factory block machining= a true compression around 7.8:1..lowest I've calculated was 7.2:1, due to HUGE factory chambers in the heads too. The .509 cam is not designed for use under a true 10:1..There are much better cams that will run and make some power with the lower squeeze..Sorry I'm just reading this now..lol