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G Head Rebuild

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BWB

10-07-2002 17:11:04




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I have a 1951 G that I pull. It dynoes 52 HP. and has either .90 or .125 over high comp. pistons. I'm fixing to tear it down and try to get more power out of it through the head. This is my first pulling tractor so I have no experience in how to get power out of it. I have a few questions. I plan on using the factory head. How much should I have it shaved 1/8", 1/4", or more? I want it to have alot of compression, but not too much as to have problems out of it. Should I put in D valves? Port and Polish? What type of manifold is the best and where can I get it? What is the term "pinning the head" mean, and should I have it done? Has anybody had any experience from having their cam done at Robert's? He said he could give it more low-end torque. Thanks for any info.

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Jack

10-08-2002 08:07:06




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 Re: G Head Rebuild in reply to BWB, 10-07-2002 17:11:04  
I am getting ready to tear my 53 G down and do the same thing.While I am at it I am going back with a propane manifold from Bob's triple G service.My G fluctuates between 52 and 53 hp at 540 pto but jumps up to 55 at 450 pto rpms with aluminum pistons and the old style gas manifold at 110 psi per hole.I was wondering what kind of psi I will have with the head cut down to the eyebrows,with these pistons.I would like to see 60 hp plus if possible.

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BWB

10-08-2002 11:40:20




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 Re: Re: G Head Rebuild in reply to Jack, 10-08-2002 08:07:06  
Thanks for the reply. It sounds like mine and yours are running about the same right now. Mine has a gas manifold on it too. Burns said to get a manifold from Jerry's with a 2" intake. Would a propane manifold be better? Thanks



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Jack

10-08-2002 11:52:31




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 Re: Re: Re: G Head Rebuild in reply to BWB, 10-08-2002 11:40:20  
I called Jerry and Bob both and decided to go with the propane from Bob's due to my limited cubic inches.If I had a stroked crank I would go with the bigger Jerry's manifold.I am going to match port the propane manifold when it comes in but I am not going to polish mine on the intake side for atomizing purposes.I am however going to polish the exaust.A friend of mine has the propane manifold on his and mine has the gas and there is about three hp on the dyno difference between ours and about twenty feet difference when it comes down to the last stroke,and we have the same tires and most everything else.Email me and we will compare notes.Later,Jack(TN).

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burns

10-07-2002 18:17:02




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 Re: G Head Rebuild in reply to BWB, 10-07-2002 17:11:04  
(Provided it hasn't been shaved yet) You can safely cut .250 off and it will just touch the eyebrow around the intake valve. You may need to have the push rods adjusted to achieve the proper clearance. Jerry's in Kansas offers two types of manifolds with 2" or 2 3/8" intake runner. You will need the 2". Have a good machinist increase the intake runner in the head to match the manifold. That 2" diameter needs to be carried the entire length of the intake runner and not a blending effect where the manifold and head join. This is time consuming due the fact the runner is not a straight shot like they are in the flat head. I personally do not feel the valves are necessary. The stock valves should be sufficient, especially with the eyebrow in the head (actually would decrease the air flow with bigger valves due to the shrouding of the eyebrow) If you are going to this amount of time/cost, consider upgrading the air filtration system. Get rid of the oil bath by either gutting the wire mesh and running a paper filament (stock apperance) or go with a K&N style.
The links below are of my G equipped with Crum's intake/exhaust performance stainless steel.

Link
http://home.adelphia.net/~hilltoppull/PictpipeJDG.html

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BWB

10-07-2002 19:40:40




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 Re: Re: G Head Rebuild in reply to burns, 10-07-2002 18:17:02  
Thanks for the info. I put a K&N filter on it as soon as I got it. Just turned the pipe down. I don't know much about mechanics, but what is the eyebrow you are talking about? I have never had a G head off yet, but I did have a 1948 A head off are you talking about the ring around the combustion chamber in the casting where the valves are? Thanks



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burns

10-08-2002 03:51:08




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 Re: Re: Re: G Head Rebuild in reply to BWB, 10-07-2002 19:40:40  
Yes, the cylone A & G are similar. The link below is of a G head owned by a visitor to the site (not me). You can see that the eyebrow has been milled pretty far. I have a back up cyclone head that has been milled to similar specifications. Be sure to have all sharp edges rounded as not to create a "hot spot" causing predentonation.

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JDGnut

10-08-2002 14:13:32




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 Re: Re: Re: Re: G Head Rebuild in reply to burns, 10-08-2002 03:51:08  
Hey.. nice head.. hehe.. Well.. that looks like my shop floor.. It is.. it is.. and that my head after I shaved it.. lol.. but before I put the special JDGnut touch to it.. lol... That head is shaved .250 (plus what ever before that) It is just into the eyebrows.. which have been modified since... JDGnut



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A puller

10-08-2002 16:09:31




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 Re: Re: Re: Re: Re: G Head Rebuild in reply to JDGnut, 10-08-2002 14:13:32  
what did you do to the eybrows?
thanks,
A puller



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BWB

10-08-2002 11:37:28




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 Re: Re: Re: Re: G Head Rebuild in reply to burns, 10-08-2002 03:51:08  
Thanks for the picture. I understand it more now. Are those still the stock valve seats? Would a D valve fit with it milled down that far? I'm sorry about all of the questions, but I'm not much of a mechanic. Thanks



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Scott Boehler

10-07-2002 17:17:09




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 Re: G Head Rebuild in reply to BWB, 10-07-2002 17:11:04  
Dear BWB, Contact Earl Seamans or "Seamo" online and he can answer all your question and do all the work to your head. He has done work on my G for me. Real good work too. Scott



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