John Deere G

Michael1951 · Sep 15, 2010

I was wondering how much more power a flat head would give my 1951 John deere G? I have already had it bored 125 with m&w high compression pistons. It dynoed at 50 horse power with the swirl head.

old popper · Sep 16, 2010

Michael, if you have high comp. pistons, you may not be able to hold a head gasket with the flat head. Mine ran almost ten minutes before blowing the head gasket. With high comp pistons the face of the head (flat) flexes because of the compression. If you are using it for pulling, hold on and I'll lrt you know how I come out with mine, as I am changing the gearing.

Michael1951 · Sep 16, 2010

Thanks! Thats what I've been doing is pulling it alittle bit. It does fine when it will hook up, it hasen't ran out of power yet. Let me know how you do!

jd b puller · Sep 16, 2010

(quoted from post at 09:43:55 09/16/10) Michael, if you have high comp. pistons, you may not be able to hold a head gasket with the flat head. Mine ran almost ten minutes before blowing the head gasket. With high comp pistons the face of the head (flat) flexes because of the compression. If you are using it for pulling, hold on and I'll lrt you know how I come out with mine, as I am changing the gearing.

There's plenty of folks out there using flatheads for pulling with.
You said you blew a head gasket. Did you surface the head? How about the block? Are you sure the studs are good?

I resleeve a lot of Powerblocks and every one of them was about 10-20 low in the center. Heads never run true either. I surface everything that comes in, whether it looks like it needs it or not. If the surfaces aren't flat, you'll blow a gasket.

buckeyebrierhopper · Sep 16, 2010

hey michial, i have been running the same as what you are wanting to do. some where in an arround 75 hp.if all surfaces are ok ,run about 10-15lbs more torch on head bolts,back off timming to about 18-19 deg. probebly need to run higher octane fuel or you will detonate,whitch could cause other problems. good luck. if you want to talk to me ,937-483-8630. dan

The Dukester · Sep 17, 2010

Michael, I had my '51 G bored .090 over (wanted to leave a little in case I wore it out), put in 6.5:1 Hinrich supplied alumy pistons, had the block deck checked for straightness (it was okay) and had about .125 took off the head which it needed, good valve job, little carburetor work and tuned on dyno and I'm pretty happy with it...dyno's 58-60 hp on the PTO and pulls 62-63 hp on the belt dyno. It has about 130 lbs. compression and still runs okay on GOOD regular gas...plowing, pulling, whatever, starts good...had the starter rebuilt just to be sure. It might power out in 2nd gear on a really good track but never in low at 6500 lbs with 14.9's. Won quite a few pulls...beat only when I can't get tires to hook. Nice tractor...terrific power in 6th gear, real fun to pull hayrides, lotsa noise and really "moves out" and climbs any hill so far, kids love it.

Michael1951 · Sep 18, 2010

Thanks! I will give you a call!

John Deere G

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