Originally Posted by AMX69PHATTY
Not that I'm an expert, but the way I understand it is
that forged pistons are for high rpm reliability, like more than 6500.
I think Perormance American Style says cast pistons are ok for up to that much.
So for the rpm's yu're looking for cast pistons should be ok.
But, cast pistons come with what ever dish volume they are,
whereas forged pistons can be ordered however you want them.
So lets see, you have a 401 .030 over with stock 58cc Heads right ?
9.208 Deck Ht., 3.68 Stoke, 5.858 Rod, alll nominal
So if we make a target Deck Clearance of .005 in the hole,
you need a piston with a 1.505 Comp Hieght,
and to get 9.5:1 compression, you'd need a 28cc dish.
So if my numbers are right you need a 28cc 1.505 Comp Ht Piston to get 9.5:1 Compression.
I believe stock 401 Pistons are 1.508 Compression Hieght.
Trouble is most aftermarket replacement pistons are shorter as you've found out.
Please let me know if any of the specs are different for the parts you have.
I think the cam you have would be ok with 9.5:1.
did you keep the lifters in order as to what hole they came out of ?
Let me know what compression ration you're after and your specs
and I'll do what I can to help and run calculations to help select pistons.