WC Rod Bearing Clearance

I have a 37 WC. Does anyone know the rod bearing clearance for that engine. I think mine are a bit too tight. When I tighten the caps, the crank refused to turn.

The WC service manual agrees with what Gerald wrote. "The bearings should have .002 to .003 oil clearance when properly fitted."  Now that it is several years ago since I did my WC I can't remember how much shim material was needed on each side of the rod caps.


Edited by TomMN - 23 Mar 2012 at 5:56pm

Thanks for the help. I may need to use some shim stock. Our parts house didn't have any shim material in stock. What kind of material is best to use?

Look for an envelope of brass shim stock at a hobby shop or hardware store that carries the K&S line of brass pieces.

One other thing to check, the bores are never centered in the caps, so reversing a cap is guaranteed to lock up the engine.

You probably need shims between where the cap and rod touch. I thought those were original in WC engines. Look in the bottom of your wash tank.

Any good car parts place should have plastigage for checking clearance. And might have shim stock. Shim both sides of the rod cap the same ammount. As a test cigarette paper is .003" thick but won't stand up to the engine running. Fastenal and McMaster-Carr I'm sure have all kinds of shim stock, but probably not in the local Fastenal store.

Gerald J.

Small Parts is where I have purchased shim stock online.  The thin metal can be cut with a scissor.
http://www.smallparts.com/shims-shim-stock/s/16413251/ref=gw_c_m_s

Or you could hone them out to the proper diameter with no shims then you won't need them at all.  We did that on my RC:
http://home.comcast.net/~old_allis/ac-RC-engine5.html

Here is a video of the RC engine assembled with no rings to show there is no drag with all rod and main bearings torqued down and .002 oil clearance on each .
[TUBE]5tq7EbSh2kc&list=UUcuxd1GDOT3KuUMf5maX8ug&index=41&feature=plcp[/TUBE]

This was of course an extra step and I had to take them out and put the rings on and reassemble but it was fun to see that nothing was dragging.  I should add this was only done on the rods, I did use shims on the main bearings, they can be seen in the video.  I used plasti-guage to check everything.  The crankshaft should roll easily when it is fitted properly, this can be checked before any rods are put on.








Edited by TomMN - 23 Mar 2012 at 7:00pm

Nothing like doing it Right the first time Tom.

Thanks for all the great help. All was going well and then one of the bolts that hold the caps on stripped. It wasn't even to torque. Now I have to wait until I can get more.