These brass shims in the bottom end of Allis C?

[atlarge54]

The last time I was into an Allis C engine was well over 15 years ago. This tractor leaked so much oil out of the front seal it ruined the front tires. The rear leaked so much oil when I started using the tractor in the spring it was almost like an automatic with a torque converter there was so much slipping. I did a quick Muldoon rebuild. All I purchased were cam bearings and a gasket set. I ground the crank in the block using an electric motor and a belt on the crank pulley. I used the old main and rod bearings and put brass shims behind them to make them fit better. I never measured anything, went completely by feel. I would venture a guess that some of the mains were .060" or more undersize. The rods I just polished journals and same as the mains, brass shims behind the bearing shells and fitted until the felt "nice". The tractor has been in operation ever since with no leaks or knocks. I usually change plugs once per season due to oil fouling, other than that it runs great.

Now I'm into an engine that has low hours on a rebuild (water down exhaust?). Mains and rods are ground .010"and the crank/ bearings show very little wear. This process of shimming rod and main caps right out of the factory has me scratching my head-----what is the thought process going on here? Do any other old tractors use a similar process? How would a would a properly fitted assembly be shimmed? When I pulled my plastigage out of the toolbox it crumbled into dust.

These old C's are perfect for my mowing needs and are not "high value" items. I'm just rebuilding one for a degree of self satisfaction. I don't normally pay more than a few hundred for a tractor and can afford to dump some money into one. This is just a keep busy morale building game for an old fart.

 

[rustred]

Most old engines from before the 1940’s and 50’s are shimmed. The deal was to remove shims as the brg would wear. On my wk40 I had the rods resized to the crank and got rid of them shims. Got the clearance to .0015 and done.

 

[JOCCO]

Not sure i understand all this but use plastic gauge and add or subtract shims. Procedure is the same for any rod or main if shimmed. If rod is messed up it will need to be reground and rebored. Generally this is for Babbitt rods /mains not inserts.

 

[rustred]

Not sure i understand all this but use plastic gauge and add or subtract shims. Procedure is the same for any rod or main if shimmed. If rod is messed up it will need to be reground and rebored. Generally this is for Babbitt rods /mains not inserts.

The McCormick WD 40 used brass shims in the insert brgs. Kind a crazy idea anyhow as brgs wear egg shape not the name amount all around. But ya more common on the Babbitt brgs. Plus they are a way heavier brg. But then everything was built heavy duty back then. Yes check with plastiguage.

 

[atlarge54]

Does anyone recall old timers actually pulling the oil pan and removing the shims to "fix" the engine? Was it ever a standard procedure on the farm?

 

[JOCCO]

Does anyone recall old timers actually pulling the oil pan and removing the shims to "fix" the engine? Was it ever a standard procedure on the farm?

In my world it was. It was common to replace or reshime rods/mains.

 

[Mike(NEOhio)]

I got a set of .010 undersize rod bearing inserts for an Waukesha that came with one set of .002 brass shims in each box. I believe the shims were to be used on assembly to be taken out to compensate for wear.