fixerupper
Well-known Member
I'm working on an F20 that had aluminum 3 7/8 overbore pistons that I am led to believe are M&W. A couple of the pistons were not what I call acceptable after I got them out, they were white corroded in very, very tight. No magic soaking elixor was ever going to penetrate that white stuff. After following some suggestions from the Farmall site I found a good used set of 3 7/8 aluminum pistons and sleeves that are claimed to be 8000 foot altitude. Today I finally had the time to compare the old pistons out of the tractor with the 'new' ones and they measure the same distance from the pin to the top of the piston and the ring lands are in identical locations.
The numbers on the pistons is what is puzzling me. Inside the piston skirts of the old pistons I found MWM or WMW cast in one side of the skirt and A1082 or A1092 cast into the other side, the 8 or 9 was fuzzy on all four pistons so I can't tell which one it is. The 'new' pistons have the same MWM inside the skirt but the number is clearly A1093.
Do any of you guys know anything about these numbers? Is there an M&W reference chart somewhere? The reason I ask is one of the 'new' pistons has a small chunk broken off of the skirt, I'm not too worried about it with this slow reving engine but I do have one original piston and sleeve from this engine that are good and could be used to replace the one with the chipped skirt. Both pistons are 3 7/8 flat top. Thanks. Jim
The numbers on the pistons is what is puzzling me. Inside the piston skirts of the old pistons I found MWM or WMW cast in one side of the skirt and A1082 or A1092 cast into the other side, the 8 or 9 was fuzzy on all four pistons so I can't tell which one it is. The 'new' pistons have the same MWM inside the skirt but the number is clearly A1093.
Do any of you guys know anything about these numbers? Is there an M&W reference chart somewhere? The reason I ask is one of the 'new' pistons has a small chunk broken off of the skirt, I'm not too worried about it with this slow reving engine but I do have one original piston and sleeve from this engine that are good and could be used to replace the one with the chipped skirt. Both pistons are 3 7/8 flat top. Thanks. Jim