Its an H22, and this 87m stamp can be seen on each piston looking up from the oil pan.
Would it be safe to assume that these are 87mm pistons and not for 87.5mm of 88mm bore?

 

no, it's some kind of cast #. i actually ordered the wrong size pistons, mine said 84m so i ordered 84mm pistons turned out to be 85mm bore. i called eagle who i ordered the custom set through and thats when the told me thats just cast # so they sent me the correct pistons.here a pic of a different set also 85mm but has 81m d4. i found out the hard way.

 

Could you tell me exactly where on the piston I should measure

 

ok, i usually take 3 measurements to see my tighest p to wall clearence or biggest part of the piston. take your measurements here then 180 degrees opposite rocking the outside mic slightly to get the most acurrate reading. you can get your piston size from this.





Modified by boosstboy at 8:28 PM 1/1/2008

 

Thanks for the info