Piston Diameter for Micrometer

[txleadfoot]

What is the factory piston diameter so that I can purchase the correct size micrometer?

[mkodama]

The bore of the M42 engine is 84 millimeters, so the piston diameter would be pretty close to that.  

[peerless]

The bore of the M42 engine is 84 millimeters, so the piston diameter would be pretty close to that.  

You need a 3"-4" Micrometer. .0001 accuracy is nice. To convert inches to millimeters multiply your measurement by 25.4.

I just recently measured a set of M42 pistons. The stock pistons are stamped 83.98mm. Take your measurement at the low end of the skirt, about a 1/4" up from the bottom. Measure it in a few different points and take the largest number. 84mm bore size equals 3.307"

#1 3.3060 (83.97)
#2 3.3060
#3 3.3055 (83.96)
#4 3.3060

[Boyracer]

Are those lightened and shot peened stock rods in that photo?

[peerless]

Are those lightened and shot peened stock rods in that photo?

Why yes they are.

I can actually get these done for you. I do these on every engine I build. I also do them for anyone who wants to send me a set of rods. I have many more pictures I can show you of other rod sets.

I charge $275 for a 4 cylinder set. That includes polishing the side beams, shot-peening, re-sizing the big end, installing new wrist pin bushings and re-sizing to your wrist pins, static balancing, new rod bolts, and new wrist pin clips. (6-10grams is removed from each rod during the polishing and balancing process. The rods are not specifically lightened other then the side beam flash removal, polishing and balancing)

PM if your interested. (I charge $300 for a 6 cylinder set)