piston ID

Y'all

Any body know what these pistons are?

casting # 1166757 with BUICK

some say ALCOA B ,others FF BOHNALITE others STL.4

Thanks

Judd

If you can find an old automotive machine shop, if there are still any that have some older aftermarket piston listings from aftermarker sources, these catalogs should have those GM casting numbers and possibly the aftermarket crossover for the other pistons (which might already be replacement pistons) so you could track the application.

Hope this helps,

NTX5467

Give us the cylinder bore size so we can figure which engine is involved

mrbuick714

They came out of a 55 Super block that was rebuilt at some time. I was trying to figure out if they were 55/56, std .040 over or what.

If they are "standard" size, there will be no stampings on the top of the piston, per se. If they ARE an oversize, when you clean the carbon off of the top of the piston there should be a stamping of the appropriate oversize (i.e., .040 for .040 oversize, for example). Typically, it takes .030" overbore to get a clean, bore on a used engine from the standard production bore size. Some engines might vary in that respect, but from what I saw at the machine shop I used to frequent, that was the usual scenario.

Some hot rodders went for the max overbore for an alleged edge with the additional cubic inch or so it would yield over the normal +.030 bore size. The best rule of thumb is to use the least oversize boring that will clean up the cylinder walls to fresh metal. Of course, your machine shop person will need to measure where the starting point is to determine just how much is left that can be overbored to get a good cylinder wall surface. Of course, such overbores will also require new pistons and rings and such, which can also have a bearing on how far the overbore can go too (the availability thing).

Enjoy!

NTX5467