a/b pistons

[ghiaguy130]

how can you tell the difference in a/b pistons, and whether they are strocker or not?

[Marc]

The compression height (distance from top of piston to centerline of wristpin) is 39.6mm/1.56" on "A" and 34mm/1.34" on "B". Generally -but not always- "A"s will have longer skirts than "B"s too.

[Mad Manx]

39.6mm/1.56" on "A" and 34mm/1.34" on "B". Generally -but not always-

I have 4 box's of Mahle 94B (12 pistons) that all measure 35mm - 1.378
so I have found it is always best to check.

[Marc]

At 34mm the compression height would be theoretically ideal for a stroke of 80.2mm; yours with 35mm would be just right at 78.2mm. Is there anything on the box labels that indicates the dimension? I'm wondering if Mahle has changed their standard for "B"s...this would be good news for someone building a 2165 or 2176, could even make it practical to use them with a 76mm stroke.

[vtec this]

i have a 76mm stroke, with 87mm pistons. i am about to buy some 94's, but i think it would be nice to get pistons that do not need to be cut at the skirts. i thought (according to some) that you could use a's on strokes up to 76, but i had to do a lot to make them work. they hit the crank before i shaved off quite a bit of the skirt.
the only thing, is that the a pistons put the pistons out of the cylinders, and i had to put spacers, making the engine wider. i wonder what would i need to do to get 050 deck height using b pistons?

[500LbGorilla]

My 88's were out 0.080" when I put it together. With b pistons, you are talking about a difference of 0.220" or so. You'd have to cut 0.090" off the barrels or so to get 0.050" deck, but best to measure it out.. cases and rods can vary. The other alternative would be a longer rod, like a 5.5" rod and a thin deck shim.