View Full Version : Engine: Thin layer of foil between main bearing shell and bearing cap.

08-03-2014, 05:36 PM
I was helping a friend get a 259 ready for his 51 project. When we pulled a couple of main bearing caps, there was a thin foil between the shell and cap. The bearings looked like they had normal wear and the crank looked good. Was this some attempt to shim the bearings, or am I missing something else. In any case, we are replacing the bearings. Anybody else seen this? The engine looks to be from 61 or so based on the serial number.

08-03-2014, 06:20 PM
The bearing shells have been shimmed to bring the clearances within specs. I've done this if the crank journals look good, but standard bearings have more than the recommended clearances. When you replace the bearings check the clearances closely. If they exceed the allowable clearance or are at the upper limit of clearance, you may want to shim the bearings, too. Shim stock is available in many thicknesses. I usually shim the bearing caps rather than the block, so as to avoid occluding any of the oiling ports in the block.

08-03-2014, 07:01 PM
Yes, back in the bad old days, builders shimmed behind the bearings or between the cap and block. Chevrolet stovebolt sixes were still leaving the factory with shims up into the mid-'50s.

No, it's not good science and not found in the Studebaker Shop Manual as a recommended procedure for V8s. Today, we line hone the block main bores and rod bores and/or grind the crankshaft to get the clearances within the allowable range.

Maybe, take the block and crank to a shop with a dial bore gauge and find out what is really going on in there.

jack vines

08-03-2014, 07:13 PM
we plan on using new std bearings. If the clearance is too much, we will go to plan B - a 289 full flow that is mostly rebuilt already. Don't want to go down the slippery slope of putting too much money in a 259 partial flow. I know they are good engines but ... Plan C is (ugh) a good running chev 265!!! All well, his car, his money.

08-04-2014, 04:46 AM
You can still find these shims. If everything was OK, I think I'll go the same way.