IH UB 220 power unit mystery (long)

Probably should post this on the engines board but I think it will get more exposure here.

Mechanic friend of mine working on a Galion motor grader with a UB220 gas engine. Compression so low it wouldn't start, less than 50 psi on ALL cylinders. Took head off and found it had already been bored .060. No sleeves so block is junk unless customer wants to go to the expense of boring all6 and putting a repair sleeve in each hole and taking it back to standard bore. We can,t turn up standard pistons either.

What we have found so far is that the bore and stroke is the same as the C221 tractor engine but the rods and pistons are different, different compression height on the pistons. Appears to be a truck engine since is sleeveless and it also has the cross hole thru the block for the throttle linkage as on the old IH trucks. Original casting # was 2XXXXXR1 but has been ground off and 306750 stamped in its place.

Does anyone know what we really have here????????

Also, does anyone know if the bolt pattern on the back is the same as the C221, C263, D236, or D282 tractor engines????? I say it is but mechanic says no. Have found a running D282 we could put in if it will bolt in.

Basically, what you have is a version of the old Black Diamond [BD] 220 truck engine. There were two variations on this engine, the straight valve and the tilt valve...straight valve being the older of the two and a direct descendant of the old SD-220 truck engine.

So determine whether you have the straight valve or the tilt valve engine, and then look for parts for the truck engine. If you get a valve cover gasket set or a top engine set, it may come with two valve cover gaskets. If the narrower one fits, it's a straight valve engine; if it takes the wider one,it's the tilt valve engine.

Pistons ARE different between the straight valve engine and the tilt valve engine; use the wrong one and you'll ed up with something like 13:1 compression instead of the stock 6.5 or 7:1.

The truck motor has the crank around 1/4 inch higher in the block than the tractor engine. I mated a BD 264 to an H rear end and had to redrill the backplate to make it line up.

Do you have the pistons out? If the pistons are in good enough shape, why not just a new set of rings? Most any machine shop can find rings, my shop just sends a piston to Hastings, and it comes back with rings on it.