Welcome! Please use the navigational links to explore our website.
PartsASAP LogoCompany Logo (800) 853-2651

Shop Now

   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver

Attention Forum Users: On the 28th of December 2023 at 9:00am Central Time, we will be taking the forums down for maintenance while we prepare the new forums for your use. Please click here for more information.

Tractor Pulling Discussion Forum

To much compresion JD G HELP!

Welcome Guest, Log in or Register
Author 
TROUBLE

05-24-2004 19:54:19




Report to Moderator

I let a middle man do some work on my engine for my 47 GM.Its got M&W .125 over with one spark plug relef welded Told him to just shave the block.Well he took .200 off.Then i told him just shave the head and you gessed it .200 off!Now i need some addvice WHAT to do.




[Log in to Reply]   [No Email]
hardydog2

01-26-2006 10:45:34




Report to Moderator
 Re: To much compresion JD G HELP! in reply to TROUBLE, 05-24-2004 19:54:19  
My father has a 46 G that he pulls.We've done modifications to the pistons, as well as 9 1/4 stroke. It compression tested @ 225 lbs. We run 116 octane. We've found timing is absolutely crucial. So as lon as it's timed properly you should have no problems.



[Log in to Reply]  [No Email]
JL

05-26-2004 15:21:22




Report to Moderator
 Re: To much compresion JD G HELP! in reply to TROUBLE, 05-24-2004 19:54:19  
Any guess's on what kind of horsepower that G has now? I'm curious to hear. Or is more info needed than whats posted. Thanks. Sounds like it ought to be a mean one now!



[Log in to Reply]  [No Email]
JDGnut

05-25-2004 08:52:43




Report to Moderator
 Re: To much compresion JD G HELP! in reply to TROUBLE, 05-24-2004 19:54:19  
About the plug relief welded.... I am guessing that they filled in the relief in the piston oppositte the plug... The only problems I see is that you will have to run high octane fuel... (normal for a pulling tractor.) The other minor problem is when you take .200 off the block it cuts into the cut outs in the block for the spark plugs.. this sometimes cause the head gasket to leak... it can be welded and resurfaced.. or I have seen them epoxied or even JBwelded... (another trick is to have the welded or filled in that area to prevent leaking.)

But .200 off the head and .200 off the styled head... WILL be no problem... (not sure how much you increase by modifying the piston.. but I would run it...

If you have a problem with the compression... 2 Things can be done to lower it.. One mill the tops of the pistons down.. Two... between the crankcase and block... use more than one gasket.. or have a thicker gasket made.. (Lubbock Gasket can make one.) One the head gaskets.. we have had the best luck with the stock JD gaskets... Good Luck..
JDGnut

[Log in to Reply]  [No Email]
JDGnut

05-25-2004 20:10:44




Report to Moderator
 Re: Re: To much compresion JD G HELP! in reply to JDGnut, 05-25-2004 08:52:43  
Trouble... Drop me an email.... JDGnut



[Log in to Reply]  [No Email]
G-MAN

05-25-2004 07:45:40




Report to Moderator
 Re: To much compresion JD G HELP! in reply to TROUBLE, 05-24-2004 19:54:19  
I agree with buickanddeere. You need to determine just what your compression is before panicking. If it ends up being too high, you can flycut the tops of the pistons down.



[Log in to Reply]  [No Email]
520-LP

05-24-2004 20:19:45




Report to Moderator
 Re: To much compresion JD G HELP! in reply to TROUBLE, 05-24-2004 19:54:19  
Give us a little more information.What kind of head are you using the regular head that came off the 47 or a flat head from an unstyled tractor? how much compression do you have?



[Log in to Reply]  [No Email]
TROUBLE

05-25-2004 05:07:38




Report to Moderator
 Re: Re: To much compresion JD G HELP! in reply to 520-LP, 05-24-2004 20:19:45  
I using a ramp type head shaved to the eyebrow.I have know idea what kind of compresion im going to have. Thats sort of what im asking.How much compresion,will it blow head gaskets.Thanks



[Log in to Reply]  [No Email]
ToddF

05-25-2004 07:57:30




Report to Moderator
 Re: Re: Re: To much compresion JD G HELP! in reply to TROUBLE, 05-25-2004 05:07:38  
I'm not sure what the stock compression ratio on your G started at so I did two quick calculations.

The first assuming a stock 6:1 compression ratio, 6.125" bore and 7.00" stroke. After changing to a 6.250" bore and removing .200" from the head and .200" from the block, the new compression ratio is 8.34:1.

The second assuming a stock 6.5:1 compression ratio, 6.125" bore and 7.00" stroke. After changing to a 6.250" bore and removing .200" from the head and .200" from the block, the new compression ratio is 9.43:1.

I can look up the stock compression ratio in a book later and tell you closer if you would like. I doubt the stock comp. ratio was over 6.5:1; this being the case you look OK. You likely will have to use higher octane fuel if you are up over 9:1, I don't know much about that. Somebody else on here may know as a rule of thumb what compression ratio 87 octane pump gas will start detonating on a large bore engine. I believe that generally large bore engines require more octane than small bore engines for a given compression ratio. I have one at 8:1 that seems to run fine on 87 octane pump gas.

[Log in to Reply]  [No Email]
G-MAN

05-25-2004 13:37:38




Report to Moderator
 Re: Re: Re: Re: To much compresion JD G HELP! in reply to ToddF, 05-25-2004 07:57:30  
Stock compression for a "G" is down in the 4.3:1 range or so. They were all built as all-fuels, hence the low compression ratio.



[Log in to Reply]  [No Email]
ToddF

05-26-2004 08:10:14




Report to Moderator
 Re: Re: Re: Re: Re: To much compresion JD G HELP! in reply to G-MAN, 05-25-2004 13:37:38  
I forgot to look up the compression ratio of a stock G last night. At 4.3:1 comp. ratio to start, the new ratio, with shaved block and head, and 6.25" pistons and the same wrist pin location on the piston in reference to the top of the piston etc., is 5.25:1. It is interesting to note that with such a low starting compression ratio that it really requires quite a substantial decrease in compressed volume to get the compression ratio up. A mistake of almost 1/4" really doesn't seem to have a drastic effect, although if the intended outcome had been 9:1 or 10:1 then there would have been trouble.

[Log in to Reply]  [No Email]
JDGnut

05-25-2004 20:05:34




Report to Moderator
 Re: Re: Re: Re: Re: To much compresion JD G HELP! in reply to G-MAN, 05-25-2004 13:37:38  
M&W style pistons.. with no milling should be about 6.5 to 1..
JDGnut



[Log in to Reply]  [No Email]
how much compression?

05-25-2004 05:48:25




Report to Moderator
 Re: Re: Re: To much compresion JD G HELP! in reply to TROUBLE, 05-25-2004 05:07:38  
need to know just how much compression...my G has well over 200 pounds and the stock head gasket holds it find.



[Log in to Reply]  [No Email]
buickanddeere

05-25-2004 13:53:48




Report to Moderator
 Re: Re: Re: Re: To much compresion JD G HELP! in reply to how much compression?, 05-25-2004 05:48:25  
Cranking pressure and mechanical compresion ratio are related but different. Unless planning is done, just throwing parts and work at a project willy nilly, just costs time, money and frustration. Being 400 thou shorter, setting the valve lash will be a bear unless the push rods are shortened about 400 thou as well. This engine should run on pump gas and at worst, a 25% 100LL aviation to 75% 94 octane pump gas blend. Too lean and/or too hot and she will knock anyways.

[Log in to Reply]  [No Email]
buickanddeere

05-25-2004 05:45:48




Report to Moderator
 Re: Re: Re: To much compresion JD G HELP! in reply to TROUBLE, 05-25-2004 05:07:38  
Depends if new premium quality studs, tall nuts, hardened washers are used along with cam assembly lube and a torque wrench. "O" ringing a copper head gasket can help too. Of course if it knocks and detonates, then the pressure spikes will blow any gasket, pound bearings and crush piston ring gooves. How about CC'ing the heads and calculating the mechanical compresison ratio? What cam are you using? What fuel do you have access to.

[Log in to Reply]  [No Email]
TROUBLE

05-25-2004 20:24:00




Report to Moderator
 Re: Re: Re: Re: To much compresion JD G HELP! in reply to buickanddeere, 05-25-2004 05:45:48  
Thanks for all the replys.I got it running to night it sounds good and not to nasty.It sounded like a little thump in the rods when i opened the throtle so im going to got some VP from a frend and try that.Thanks



[Log in to Reply]  [No Email]
a puller

05-25-2004 21:14:29




Report to Moderator
 Re: Re: Re: Re: Re: To much compresion JD G HELP! in reply to TROUBLE, 05-25-2004 20:24:00  
its gonna pick up compression when it breaks in too...let us know what kinda power u got...sounds like its gonna be a mean stock G with the big head and all....keep us updated...



[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:


TRACTOR PARTS TRACTOR MANUALS
We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home  |  Forums


Copyright © 1997-2023 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy