John Deere G, 1951

rlp

Member
This is my G that I just bought. The motor was stuck and it took a lot of work to get it free. I put a 20 ton jack and put some pressure on the pistons, then I took a crowbar and pryed on the flywheel teeth against the starter. After about 1000 times back and forth I finally made a full round on the flywheel, ha ha I'm going to see if it will run without rebuilding it. I smoothed out a lot of humps and bumps in the bowl areas and opened the intake port from 1 and 3/4" to 2". I might also make a cold intake manifold for it. I would like to get a carburator with a little more air flow but I don't know what to use yet. Sugestions? I wish it had 10&1/2 to one instead of 4&1/2 to one compression ratio; I think I could get 50 hp instead of 38 hp.
I wish that I had taken a before and after picture of the head so you could better see the difference. 10 hours of work on the head but no money! Free horsepower, ha ha.
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John deere made a kit back in them days that incuded high compression pistons and a gas manifold that gave the G 50hp. They did that for thier late styled A with gas engine had the same HP. My 47G has it and would push 50hp on a proney brake off the belt pulley
 
Where did you get your pistons? That's what I need. Do you know what they raised the compression ratio to?
 
Well I have lots of time to waste, and besides, it's good therapy! ha ha. See that Ford backhoe in the picture? I ported and polished the head on it. It has quite a bit more power than a stock Ford. Stock is 60 hp. I'm guessing it has 70 or 75 now. It will push almost as much dirt as my boss's 310 John Deere and it has around 100 hp I think.
 
Do a good overhaul on the engine...bore it if it needs it and put in new alumy 6.5:1 gas pistons, good valve job and carburetor cleaning. Perfect tune job. Maybe take 100 thousandths off the head..no more and you'll have 55-60 horse and it'll still burn pump gas, be easy to start and use for anything. You DON'T WANT 10.5:1 compression...trust me.
 
awesome tractor i'm jealous! pistons can b had all over. 6.5-7 to one is plenty with that huge bore, any more wont burn pump gas n gets temperamental, real high like 10 or eleven wont lug down either & very hard if not impossible to start without pulling. not a useable tractor & marginal for pulling even. a good cam helps alot.
 
Thanks for the info on the compression ratio of the pistons, but I still would like 10 1/2 to one pistons. That's what I put in my 460 Ford engine and it works great. I just have to dial back the ignition till it stops pinging. Gets good fuel milage (for a 460) and it runs great on propane. I know you don't agree but if you know where I can get some, let me know.
 

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