Piston scoring D-21/210/220/7030 engines

Thanks DR. I've heard of this before. Had this happen about 20 years ago while breaking in a fresh rebuilt D21 engine on the dyno at a moderate load. 

I got the 220 engine fired up today and it sounds fine, but was only ran for a couple of minutes as it was supper time. This engine has the later model crankshaft driven oil pump and deeper oil pan on it. The oil capacity should be 21 quarts. This tractor has passed thru how many owners and technicians over the years ?? Who knows ?? Anyway, there isn't a serial number tag on the engine block, so I'll have to try and determine by the chassis s/n if it had this newer oil pump or not from the factory. I did notice that the engine oil level dipstick had been modified by someone in the past. It has been made longer, which would cause you to NOT fill the engine to 21 quarts capacity. I think it's about an inch too long, so we've probably been maybe 2 gallons LOW on oil all these years??  So, I will be changing that for sure. It also (at some point) had new slotted -.010" rod bearing shells installed and they did not get the connecting rods turned around as was required with that change to updated parts. So, now that has been corrected. It now has the newest "ARP" brand connecting rod bolts installed and torqued to 85 ft lbs. All six new wrist pin bushings were needed as they should have been replaced when the engine was OH'd before sometime in its past. One more thing to be extremely careful of when installing sleeves in these engines. Obviously, you want to clean the block very well and dry fit the new sleeves without the Orings on them. They should go in easily and be able to rotate when installed fully in the block. Remove the sleeves, roll on the new Orings (two black on the top two grooves and orange in the bottom groove) and then with a pocket screwdriver go around each one to be sure nothing is rolled/twisted. Now, the next important part: wipe Mazola cooking oil lightly on each Oring with your finger. Also wipe the inside of the lower block bore too. Nothing excessive !! just a light coat on the rubber and in the block bore. Shove the sleeves in and bolt them down. Excessive lube between those Orings can cause things to squeeze the sleeve and when you've only got .003" skirt clearance, you cannot afford to have that happen. Maybe the snow storm won't be so bad tonite and I can get the front axle under it and get in a hr or so of run time tomorrow. We'll see !!

I've thought of a couple of other things too that could contribute to this problem : A muffler versus a straight pipe. A straight pipe might be enough of a benefit (100 degrees pyro temp cooler ) to offset altering HP upwards a bit. The fan belts on the D-21/210/220 were those da** shoestring width sized belts that had to be kept very tight or there was a reduction in fan/water pump speed at full throttle, especially when the tin pulley on the fan got worn. It makes sense that 180 degree coolant temps would have to be better than running right on the edge of the red when it comes to piston skirt diameters. Lastly, your M & W's probably are a little looser fit than .003".  For sure there's less blow-by with their top ring design and that would make for a cooler piston too, wouldn't ya think ??