flathead on a 48 G

[garrettjdg]

Hello everyone, I have a 48 G and have tried reinforcing the deck of my 486 flathead, jd headstuds, resurfaced deck of block and head, copper and factory jd gasket and still cannot get head to seal, even cut .300" off of aluminum pistons to relive compression. even with reinforced deck think its still flexing at the top. I have over 8000.00 in this tractor and want to make power but don't want to spend 2000.00 more on murphys head and manifold. any input anybody? Thanks

 

[buickanddeere]

You can't make a silk purse out of a sow's ear.
Figuring if you had went with the Murphy head in the first place. Fewer headaches, no re-work and more power. You would be ahead of the game.
Order a Murphy head and sell the old flat head to some other overly optimistic puller.

 

[garrettjdg]

Sad part is I haven't even had anything attached to the drawbar except a Farmall 350 at the fouth of July party at a local farm, that was funny, except for the trenches in the driveway. Yes I now understand, I was just hopin....

 

[JD ONLY]

How much compresion do you have? I ran a flathead on my 48 with m&w pistons for years.It had about 185# and was good for a gasket every 2years.I've been told that the right fuel and timing will cure that.Bob at triple G ran that with 210# with no problems at all.We both used stock JD head gaskets.

 

[buickanddeere]

True. Detonation from too lean and too much advance, low octane fuel etc will make any any engine fail.

 

[garrettjdg]

I did check the static compression at one point and if I remember correctly it was about 230 psi. I have run nothing but 114 Torco for fuel, mixed about 50/50 with 93 octane pump gas. Don"t really know where the timing is, the impulse on the flywheel I think is like 24 to 26 degrees BTDC, and I have it backed up before that. The pistons in this tractor I think are some china built Hershel-Adams units. They have the cut outs on the sides to clear the spark plugs. Came with the reman block from nnalert. The block is std bore and std stroke, but it is sleeved.

 

[buickanddeere]

This is making more sense now that we have more info.
While a factory flat head works fine on a G with factory stock pistons. With the kind of combustion chamber pressure that G is making with those aftermarket pistons.
Keeping the factory flat head from leaking will be nearly impossible. The metal is just too thin and weak, it flexes.
Maybe time to get the cyclone head port matched, intake valves un-shrouded, bowls blended and a super dupper five angle valve job with back cut intake.
That with a Berry cam and she will make power on less compression than the current flat head combo.

 

[jd b puller]

With as much money as you've dumped into this thing, find someone (pay them if you must), to figure out what your timing is.

Did I read that right that you are running 114 mixed 50/50 with 93 octane? Roughly speaking, that equates to 103 Octane. Drop the 93 octane and stick with the straight 114. Now is not the time to be cheap.

Putting a "stiffer" head on it will likely just move your problems somewhere else. I would bet you are seeing detonation.

If it was mine, I would get the timing set at 18*, stick with straight 114 octane and go from there.

 

[JDJACK]

If you are mixing the fuel at 50-50 you are at a 103.5 octane. Maybe it's not enough. Have you tried the 114 without mixing it?
Are you sure the head and block deck are true?
Are you installing anything on the head gasket for helping it seal?
What are you torqueing head nuts to, and are you using a proper torque pattern?

 

[garrettjdg]

Thanks for all the help guys, so I have tried the impossible, literaly 5 times! I have found a 551r head and may have it cut down. What is a Berry cam? Right now it has a nice stock f120r in it. I saved 4 nice valves out of the original 551, have 4 uncut pushrods one new JD gasket and 9 new lead washers left. When the gasket was sealed (for a little while) I pulled a 3 bottom in 5th gear- did a really nice job, with both tires spinning and throwing dirt about 4 feet out of the furrow. Do you think that the 486 would still be OK back on a unstyled stock G? Because I would like to sell it, It has 4 brand new valves in it. The only other mod that was made to it other than resurfacing is that the water jackets were reinforced with nut & bolt concept. Thanks Garrett