Case vac piston size

Kenny Bill

New User
I am trying to get the engine on my vac running. Two cylinders are rusted and locked up. No chance to save them. My question is I have two usable sleeves and pistons that are standard 3-1/4? and two sleeves and pistons that are 3-3/8? . I am working on a very limited budget. Can I use two different size pistons in my engine. This tractor belonged to my Dad and I want to restore just for show. It will not be used for pulling or work.
 
I would not do so since you will have 2 different power out puts from to different size piston and good chance you will break the crank shaft
 
My oldest brother was a first rate mechanic who simply learned it from childhood. Was overhauling small engines for neighbors when he was 12 years old. Repaired tractors in his teens for small farmers on a shoestring budget and had done this a few times with no issues . Probably not ideal. he made it work more than once.
Andy
 
Hi Kenny-
If you are using this as a show tractor or even for occasional real work you should be fine with splitting up the bore / overbore sizes on the VAC. Case in point, in my younger years when I was parting out classic tractors and bought a Case DC that was in a barn fire. I proceeded to strip it down to harvest the few parts that were not cracked to smithereens from the cold fire water spray on red hot cast iron. Removing the head I found 3 sleeves at 3 7/8" and one at 4.0". Now obviously the tractor did not get taken out of service because the one cylinder was too big and that caused trouble, they stopped using it because it was in the middle of a red hot BBQ.
If you are not tractor pulling, running over rated speed RPM's, or making your living with this tractor by running it every day to till a thousand acres it should be fine. You may have a slight vibration at high speeds or may idle a little roughly. Now if you could save 400 bucks or more by using what you have and get it running and have some real fun with it then you are putting this tractor back in the running category and that is what we like to see. Better to have it together and running than torn down in baskets and boxes. Hope you get it running soon.
Thanks,
Dave Reed
Otto Gas Engine Works
Elkton MD
Website
 
I guessing that the 3 1/4 pistons are cast iron and the 3 3/8 are aluminum. If that is the case there will be to much weight difference. If they are the same material don't think you will have a problem. These are low output and low rpm engines and are pretty forgiving to unusual circumstances. Lee
 
That would make sense, but on the other hand, it would mean the 2 similar weight pistons would be paired together (1 & 4, or 2 & 3) reciprocating against the 2 other similar weight pistons. Balancing all 4 pistons in weight would seem like a good idea I guess.
 
If you are near southwest missouri,i got 2 vac parts tractors you might scrounge up a couple pistons from .
 

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