Engine Building

Tnbshr

Member
Good morning,
Im restoring a 47 John Deere model D.
I have had the the cylinders bored and will be installing modern high compression pistons. I have new NOS connecting rods, camshaft, main bearings. The flywheel and clutch assembly will be original from the tractor. My question is should I have the engine balanced? I dont want to do all this work and have a problem.
 
I dont think so either, when a kid our little hometown mechanic bored out a lot of tractors, and car engines, never did he send one out for balancing, and he wouldn't do anything unless it was done right! We were so blessed to have him!
 
What would you have to gain. I have been around a lot of race engines. They are balanced for a reason. A balanced low speed engine is a waste of money
 
One thing I'd do, when you have the pistons, rings, and connecting rods assembled, check to see if they weigh the same.

Over the years, I built quite a few small block Chevy pickup and car engines, and when I had the pistons, rings, and rods assembled, I'd weigh them on a scale that would read decimals of an ounce. Then I'd record the weight of the lightest one and grind material off the rod caps until the rest weighed the same as the lightest one. On those rod caps, there was always plenty of material that you could grind off.

Just my peculiar way of doing things.
 
If you had an O'haus scale you could do what Goose said . Balancing is a factor Say a factory balance is at 50% when changed it may go to 60% but with little consequence. Balancing is a
science to itself.
 
yes,... same thing as driving on unbalanced car tires, at 30mph wont feel a thing. at 60 or more will feel them hopping.
 
I balance everything I can. Probably
doesn't help a lot on a 1000 rpm motor.
But we have a balance guy close by. You
would be surprised how bad some old stuff
is.
 
Meant to add...

Instead invest the time to double check all the clearances. Don't assume anything!

Using aftermarket parts, anything is possible. Also getting harder and harder to find a reputable machine shop. Check everything!
 
:D

Deere D is quite unbalanced to start with. You will have to make it a two strokes or cut and reweld crank at 180 degrees.
 
The other thing you find in building small block Chevrolet engines is that the pistons will have slightly different height and rods will be a different length. The crank throws will be different. In a normal street engine this works ok. For high performance engines maybe not so much. I always put the tall piston on the short rods and/or the short throw. When I was building roller cam small journal 327s the first order of business was to check the height of the pistons, rod length and crank throws. Another thing I found was the block weren’t always decked parallel to main bearing bore. A D doesn’t need to be balanced.
 
(quoted from post at 10:42:51 09/27/20) Good morning,
Im restoring a 47 John Deere model D.
I have had the the cylinders bored and will be installing modern high compression pistons.

i am curious where you got your pistons, i have a D that i am getting ready to clean up, and i would be real interested in better pistons to go with the dual exhaust and head work.
 
My 2 cylinder John Deere experience started and stopped with the one I cranked by hand and drove on and off the trailer. As for testing a balanced vs unbalanced I would be interested if there was a gallon per hour difference doing the same task in the same weather over a three day period. Through a former employer I had access to Continental testing data. Lots uninteresting stuff. I wouldn't be suprises if they tested this scenario.
 

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