Wow, 2 cylinders .030 over & the rest stock. WTF, who does that!

probably sounds like a Harley at idle.

OK, i have been studying pistons and bore clearance. It appears that the big difference between the Mark IV and Gen VI 502 pistons is the ring size. The Gen VI use the metric thickness rings and the Mark IV use the SAE sized ones. The question is why don't piston manufacturers give the actual diameter of the pistons? They all seem to advertise the bore size the pistons fit but not the actual piston size. Looking at the SRP Replacement pistons they say they fit a 4.470" bore but are only .002" larger than stock. If the stock bore is 4.466" then there appears to be an extra .002" clearance using these pistons. I assume that you are expected to hone the bore to get the desired clearance but it would be nice to know the actual piston size before ordering them. So my question now is, what size is the stock piston for the 502?

Thanks.

the adverage piston size on a gen vl piston is 4.464 measured .500 up from the bottom of the skirt. i have usd the J E 4.470 bore piston will come with a 4.466 size . i usually finish my bores .001 biggger for .005 pw , if i coat the pistons I still finish the bore to 4.471 .

they don't tell you the piston size because pistons aren't round. they are oval and tapered. which dimension would you like ?

beyond that, pistons change dimension and shape significantly with temperature. so when you buy a piston, if you are smart, you take the time to understand what its made of, how its made what the operating temperature of your system is going to be along with the general type of service it will see over what sort of duty cycle and use those factors to define the ring pack, final bore size and final bore finish.

the answers to your questions and confusion will come from the enginners at JE or weisco or cosworth who, if you call them might take the time to tell you in 25 words or less what they have learned in 75 years of fundemental engineering understanding. the same with the guys that make the rings. outside of the general folklore and voodoo , its a topic that is a science in its own right.