[Nathan_1929]

Howdy,

I have a barn find 1941 Mercury block in the machine shop and after a parts wash, it looks like it was freshly bored, covered in grease, and stuck in the corner to collect dust for decades. It was originally 3.1875, but is now 3.280.. which is roughly 3/32 or 0.090 over. The bore is so beautiful that I would like to just run it as-is... except I'm not finding any pistons online in that oversize. Seems like 3.3125 opens up a plethora of choices.

I didn't get any original engine internals with the barn find except the old (floater style) crank. I was just looking back through the boxes of random parts (mostly Model T stuff) and discovered a box of NOS Silv-O-Lite 8-1017 pistons marked 0.090 oversize. Cool!

The pistons measure:
3.255 across the top of the piston
3.265 on the skirt just under the wrist pin
3.275 on the skirt 90deg to the wrist pin.

Hmm.. that final number is 0.005 under the bore, 3.280. Maybe these are in fact relevant to my project.. I'd definitely accept thoughts on that fit from the experts.

Since I don't have rods/bearings, and only have a rough old crank that needs attention anyway, I was thinking of just dropping in a 4" crank while it's all apart. If the pistons won't work with a 4", then it looks like I'll be refurbishing my old crank and finding some floater rods/bearings. Anyone have some for sale?

My pursuit for Silv-O-Lite 8-1017 information continues. They're not showing up in modern catalogs. Basically, I just want to see if these are suited for this application.. and even better, if they can be used with a 4" crank. Thanks for any help.