need rear main cap for 226 engine

[TX Rebel]

Anyone have one laying around?
pt# 189614 or 525609

[rkapteyn]

You need to line bore the block to swap caps.
Studebaker did not have very accurate indexing.

Robert Kapteyn

[BRUCESTUDE]

I agree with Robert; I bought an NOS replacement Champion engine (disassembled) at a yard sale a few years back, with the rear main cap missing. I had a couple caps laying around and took them to my buddy the machinist; he couldn't get either one to work-they were too far out of alignment to line bore when bolted in place. So I have a nice door stop in my shop!

[gordr]

Will one off a '38 Commander engine work? I have one of those, out of the car, and it's in tough shape. Did make it run, once, but the pistons in it are totally shot. Would need a complete overhaul. I also have a seized 226 in an M-series truck.

[TX Rebel]

gord, let me know details, pls

[gordr]

What details do you need, Barry? I really doubt that I will ever try to overhaul either engine. If I need a Commander six for something, I would seek out a 245 to build. So if you want the main cap off one, let me know. Would there be a difference between main caps from a '38 Commander and a '47 M16? Same bearing size, same seal type? I have never had the bottom end of a Commander six apart.

[altair]

You can make it fit with a little fiddling. I mixed and matched a set of mains by shimming the caps until they fit. I bolted each cap up tight with plastigage to find the lows and highs and shim accordingly. This can only be done with the crank only in the block. The bearing caps are fitted until the crank turns freely. This is a bit back yardish but it works. I did this to an old six and it runs perfect and quiet with good oil pressure. It appears that the line boring of the main caps was a random method and they could be out several thousands in any direction and this is why the bell housing has to be dialed to align with the crank, what ever direction it is. To find a cap that fit would be just blind luck. I was lucky, I mixed and matched a bell housing and it was within .001 - .002 just luck.

[gordr]

If I had to fit a main cap that was strange to the engine, I would first use the lathe to make a cylinder of aluminum the exact nominal size of the main bearing bore. Set that "gauge block" in the overturned block, and try to fit the cap. If there was lateral misalignment, I'd grind material off the cap outside the bolt bore, so that it would sit freely in the recess in the block web. If the cap interfered with the gauge block before the legs of the cap bottomed on the web, I would tighten the bolts until the cap was snug on the gauge block, but not to the point of bending the cap. Then grind enough out of the block web that a small piece of steel could be fit (on both sides, if need be) to make positive lateral stops for the cap. Make these pieces big enough to press tightly into the space available, and then drill and tap a hole for a 1/4-20 cap screw, and Loctite the stops and screws in place. That way, your new main cap will always install on-center laterally. Then send the block out to a machine shop, and have that one cap line-bored to standard size.

If the cap, when bolted down, was loose on the gauge block, you could trim excess material off the mating face either by using a mill, or else by taping some abrasive paper to a true plane surface, like plate glass or a machine table, and simply lapping. Lap a bit, trial fit, lap a bit, trial fit, and so on. The lateral centering could be done the same way.