Help me interpret cylinder measurements

[puffer@rpi.edu]

I have pulled the pistons out of my CAT22, 2F5209, and have measured the cylinders and pistons. The measurements are posted in the attached pdf file. I have also posted photos of the pistons and cylinders. You will note the excessive deposits on the top of #4 piston. That cylinder has a burned valve.

OK, now I have some questions. Please help me interpret my measurements.

First, I see that the piston measurements are very consistent from cylinder to cylinder and that the pistons are all .015" undersize above the top ring. Is that by design? It seems unlikely that it is because of wear. Next, all of the rest of the piston measurements are very close, and are what I would expect of new standard pistons. Is that correct?

Looking at the cylinder measurements there is a definite taper in the cylinders, with the top of the cylinders being as much as +.020." Also, there is excessive piston ring end gap of at least .125" at the top. I would expect around .010", correct?

Now the obvious question is what to do? Do I have the cylinders bored to +.020." and try to find .020" over pistons and rings? If so, where can I get the pistons and rings? What other options do you see? Thanks, Ray

[n7gxz]

Piston measurements look normal.

You might check around and see if a thin wall sleave is availible for a 4" bore.

Kevin

[puffer@rpi.edu]

Piston measurements look normal.

You might check around and see if a thin wall sleeve is available for a 4" bore.

Kevin

Kevin, I have seen listings for sleeves with the correct 101.6mm bore. I'll check with the local NAPA machine shop to see what they would charge. That would probably be better than new pistons as I would still have to have the cylinders bored. Thanks, Ray

[Soapy]

Egge Machine works. L.A. Calif. has a large stock of sleeves, or can make them to spec.
They have a website also, and you can order a catalogue.

[puffer@rpi.edu]

Egge Machine works. L.A. Calif. has a large stock of sleeves, or can make them to spec.
They have a website also, and you can order a catalogue.

Soapy, thanks for the information. Ray

[steeltracs]

You can have the jugs sleeved back to standard if your pistions are still good and get a new set of rings. It is possible to get over-sized rings and just power hone the jugs if there is not too much wear.(not the best method !)

[ronm]

If you have .020 wear, it will take at least .030 to clean it up, maybe more...wear doesn't happen uniformly...the way those pistons look, sleeving is probably the way to go, but you should check the ring grooves for wear, that's what will cause problems re-using them. New rings won't seat well in worn grooves. The undersize at the top is normal, to allow for expansion-clearance is measured at the skirt. Depending on how you intend to use it, & whether you're doing a full restoration, you might get away with reaming the ridge & a good hone job, on a gas engine...if it was a Diesel, I wouldn't even suggest it. For a parade tractor, or just puttin' around, it will run with that much taper-lots of engines were done that way back in the day-but if you're gonna work it hard, probly better to do it right...

[Old Magnet]

It's usually ring land wear of the compression ring grooves (vertical groove width) that kills the reuse of pistons unless you can get oversize (thick) rings and recut the grooves.

[7upuller]

Het Gang,

I had the ring groove on my 60 pistons recut. Ordered special rings. Don't have them in yet, but I'll let you know next year. LOL Too many projects. I'll get to it, after the Mack engine, or the water truck, or the CCU for Oil Slick, after the injector pump of the 14a, or the brakes on the 3t, or the pony pinion on the 17a, or..........had to take a breath. LOL

[puffer@rpi.edu]

I'll measure the ring grooves and rings and post the results to get folks opinions on whether or not I can reuse the pistons. What is the maximum allowable clearance between ring and groove? What is the standard ring thickness? Ray