Just wondering if this is a standard bore measurement? Looks like 10.16ish.... a 030 over is 10.2x right? This motor was sold to me as a "347" yet somehow I'm skeptical, how else to tell?
I've never cracked a 302 before so just to ask, these are aftermarket at the least aren't they?
yeah, don't listen to when people say they "bore it out to a 347" you have to stroke and bore it, but almost all the added cubes are from the extra stroke. Those look aftermarket pistons cause of the extra valve relief for the intake valve like 5spdGT said. They are dished somewhat so compression is probably fairly low depending on your cylinder head cc chamber. I think normally too if a piston is oversized, it will be stamped with ".030" or 4.030 somewhere on it in the middle. Don't worry that it's a 342, those extra 5 cubes wouldn't do much. Rejoice that you have thicker cylinder walls instead.
And to answer your other question, 10.16 centimeters is equal to a stock 4 inch bore, and 10.24 centimeters is equal to a 4.030" overbore, rounded up.
Where are you measuring at? At the top ridge may not be the most accurate place. Maybe try a couple inches down in the bore. You may just have a stock bore though, with the "347" crank, with a 5.315" or 5.400" rod.
I agree with Fast63. Do not worry about the extra 5 cubes
Your pushrods are not going to matter. I was talking about your connecting rods. That is something you will find a hard time measuring without removing the oil pan at the very least
I would be willing to bet you have the 5.4" rod. That includes the 1.090" compression height piston.
The 5.315" rod includes a taller piston at 1.175" compression height.
They both can make a 342 or 347 (depending on bore size).
They are after market pistons. Many manufactures will have the parts number and the size right on the top of the pistion. Clean then up and you will see. I bought a new SVO block and kept it standard bore and I have a 342.