[ekancler]

Does anyone happen to know the total relief (cc's) of the pistons used in late '70s Pontiac 400s? I've got a 1977 W72 T/A. I've read that the pistons are the same as in the base L78 400 engines. I want to know for the purpose of doing compression ratio calculations and comparing with different aftermarket pistons.

[77 TRASHCAN]

You may have to post this in the street section, many there know, for sure, they may not wander into this section, often...

[ekancler]

Originally Posted by 77 TRASHCAN

You may have to post this in the street section, many there know, for sure, they may not wander into this section, often...

Thanks for the suggestion. I'm new to the forum, don't always know where to post. What's a good general rule of thumb for when to post to the street section instead?

[Jay S]

The bevel and the valve relief’s add up to 10.5cc on that era pistons. The original pistons I have checked the compression height was 1.72”.

[ekancler]

Originally Posted by Jay S

The bevel and the valve relief’s add up to 10.5cc on that era pistons. The original pistons I have checked the compression height was 1.72”.

Thank you!