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

Shop Now

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

Discussion Forum

A engine rebuild

Welcome Guest, Log in or Register
Author 
A-man

11-08-2001 06:12:24




Report to Moderator

After pulling my '51 JD hard this summer at the tractor pulls, I am beginning to think that I don't have enough power to keep up with the pack. My "A" has 84 psi In the nuber one cylinder and has 85 psi in the number two cylinder. I am thinking about boring out the motor, and installing model "G" or "70" pistons as well as shaving the head as much as is needed to reach a compression of 9.5:1 . Do any of you seen any conflicts with the plans I have here? Will the new "G" or "70" pistons fit my stock rods. What about the block? will the oversize bores be to big for the "A" block? How much will I have to shave the head to accomplish a 9.5:1 compression ratio? Is there anything wrong with this high a ratio? Will the stock crankshaft be able to take the increased hp? Any other reccomendations?
Thank-you!

[Log in to Reply]   [No Email]
frank--WOW!!!

11-09-2001 09:50:58




Report to Moderator
 Re: A engine rebuild in reply to A-man, 11-08-2001 06:12:24  
WOW! Will the stock crank handle all that extra power? Good Question!! I doubt it! That JD will really be cranking out the power! Look out open class tractors! There is a "mean A" on the build!!! Mercy Sakes!!!!! !!!!! !!!!!



[Log in to Reply]  [No Email]
Strokes where it's at

11-10-2001 17:29:39




Report to Moderator
 Re: Re: A engine rebuild in reply to frank--WOW!!!, 11-09-2001 09:50:58  
Not Without Stroking It He Won't



[Log in to Reply]  [No Email]
A-man

11-09-2001 17:03:06




Report to Moderator
 Re: Re: A engine rebuild in reply to frank--WOW!!!, 11-09-2001 09:50:58  
HE HE HE HE HE HE..... It's good to be feared by the other tractors.... Gets them all intimidated :D



[Log in to Reply]  [No Email]
WTW

11-08-2001 14:27:36




Report to Moderator
 Re: A engine rebuild in reply to A-man, 11-08-2001 06:12:24  
I will sell you a Power block for that A and then you can put those High compression "G" pistons in it. The Hiesler head will entice it that much more if you could ever find one and it can always be added to the larger cube block later. This way you will not have to spend all your inheritance at once. HA! HA! Let me know if you are interested and I can tell you how to put it together too. If you want a noticeable Power change just as well get serious or why bother. A Hiesler head will add allot more to the Power block if one could find one. As the old saying goes "There is NO Replacement for Displacement" Good Luck, Dave W.

[Log in to Reply]  [No Email]
A-man

11-08-2001 19:45:13




Report to Moderator
 Re: Re: A engine rebuild in reply to WTW, 11-08-2001 14:27:36  
How much would it be for a power block? What are the advantages of it? Hiesler head? I guess I've never heard of them! Any info on finding one? I don't feel like tearing into the crankcase yet to install a stroker crank, so I may only have money to put in some new pistons and shave my existing head this year. Again, please tell me the differences in a "power block" and a regular JD block. Thank you!

[Log in to Reply]  [No Email]
WTW

11-09-2001 08:39:46




Report to Moderator
 Re: Re: Re: A engine rebuild in reply to A-man, 11-08-2001 19:45:13  
Powerblocks were made out east somewhere and sold through Tractor Supply Stores. They replaced the original block with their larger bore block and pistons. The piston bore was increased so much that the pistons are installed and removed from the bottom of the block. The reason for this was the cylinder head end of the Powerblock was kept the original diameter to except the original cylinder head and gasket. There were three different bore sizes of Powerblocks, 5", 6" and 6.5". They made three different 5" bore blocks, three different 6" bore blocks and two different 6.5" bore blocks. The 5" bore block models were the 5-1, 5-2 and the 5-3. The 5-1 was for the 1941-1946 model "B". It replace the original 4.5 inch stock bore. The 5-2 was for the 1947-1952 model "B". It replaced the original 5.6875 stock bore. The 5-1 and 5-2 had the same block and head bolt patterns. The difference was the water manifold patterns and the 5-1 had frame mounting holes in the bottom where the 5-2 did not. The 5-3 was for the model 50 and it had a different block bolt pattern and it also had one more head bolt stud in the head pattern, 10 verses 9 like the 5-1 and 5-2. It also replaced the original 5.6875 stock bore. The 6" bore block models were the 6-1, 6-2 and the 6-3. They all had different block bolt and water manifold bolt patterns. They did share all the same head bolt patterns. The 6-1 like the 5-1 had frame mounting holes in the bottom where the 6-2 did not. The 6-1 was for the 1940-1946 model "A". It replace the original 5.5 inch stock bore. The 6-2 was for the 1947-1949 model "A". It replaced the original 5.5 stock bore. The 6-3 was for the 1950-1952 model "A" and the model "60". It replaced the original 5.5" stock bore. The 7-1 and 7-2 model blocks were both 6.5" bore blocks. The 7-1 was for the 1942-1952 model "G" and replaced the original 6.125" stock bore. The 7-2 was for the model "70" (GAS) and replaced the original 5.875 stock bore. The 7-2 was a shorter block than the 7-1. It had two more bolt holes in the block mounting flange than the 7-1. The 7-2 also had one more head bolt stud in the head pattern like the 5-3 did. A stock "A "Powerblock has a standard bore of 6" inches and can be bored out as far as .125 Thousands or 1/8 inch without having to resleeve. Once and if you wish to resleeve you can go up to 6 1/2 inch bore (BIG BUCKS)!! Being you are just starting out you may choose to take a more economical route and the best bang for your buck is to purchase yourself a set of model G M&W standard bore 6 1/8" pistons and bore the block .125 thousands oversize. The G pistons have the same size wrist pin as the A so there is no adapting to the rod. The only thing you have to do is have the top of the pistons machined (above the top compression ring) so they will not hit the bell chamfer at the top of the block. You can run all the piston rings in there original location. This not only will increase your bore but will raise the compression. I have put many of these setups together and they work well. If you want to top it off a little more find yourself a Hiesler head for a model A, the one you want was used on A's built between 1940 and 1946. This head will bolt right on without modification, all you have to do is use the head bolt studs from the same earlier model "A" tractor (1940-1946). Hiesler Heads are another aftermarket product like the Powerblock, never intended to be put together but the advantages are very real when you do!! I have a model "A" (6-3) Powerblock that I will sell without pistons for $750.00. Hope this information will answer some questions. Let me know if you want more. Dave W.

[Log in to Reply]  [No Email]
burns

11-08-2001 11:36:19




Report to Moderator
 Re: A engine rebuild in reply to A-man, 11-08-2001 06:12:24  
As far as the head is concerned, you can shave the head down to where the last cut is shaving the eyebrow around the intake valve. With clevite aluminum pistons and .125 shaved, our A is around 120psi per cylinder. Have you considered adding a heisler head. The heisler head will give you better breathing large valves and the shape will increase your compression. A good but expensive combination for the div 1-2 class is the slow tranny A with a powerblock, heisler head, good cam, hot ignition, good tires and go pulling the heavy classes.

[Log in to Reply]  [No Email]
JDGnut

11-08-2001 08:59:32




Report to Moderator
 Re: A engine rebuild in reply to A-man, 11-08-2001 06:12:24  
The G and 70 pistons will fit your rods they use the same size piston pin. The G also uses the same length rod as the A, but the rod journal is smaller on the A. I think the pistons for the 70 will work, the 6.125 G's might be a little to much.. but I couldn't tell U for sure. I have never built an A. The A powerblocks only have a 6in bore to start. U could always have your block sleeved bigger.. Just depends on how much U want to spend... U will get more out of the engine (for pulling) by stroking the engine rather than an bigger bore.. back to the Cubic Dollar Theory... Good luck
JDGnut

[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