Division 3 or 4 jd G

[Trist48G]

Looking into building another G. A 18.4-38 tire tractor, Wanting to pull 5,8 &12 mph. Looking for advice or recommendations on what bore and stroke it would take to be competitive in the natpa circuit. I know some guys run small block and big stroke and some run big block big stroke. Any help is appreciated

 

[MSD]

I run a 10 inch billet crank with a 7 3/4 inch straight bore Raml Performance block and head. I pull mostly 6-8-12 mph classes with NATPA and have won points championships with it in all those classes. We cast the blocks to our specifications and then do all the machine work to them. This block reguires one of our performance heads to fit the block. The head I run has 3 inch intake valves and air flows 1040 cfm on a flow bench. The carb has been special modified for pulling that we also do. Has billet rods and custom pistons also. We are going away from the 7 3/4 inch blocks and doing 8 inch ones now. I have custom made gears in it so I run 2 3/4, 3 3/4, 3, 4, 3 1/2, 4 1/2. Takes some power to do 4 1/4 gear but have had it up to14.6 mph in that one already. Crankcase and transmission housing have been lightened as well as the rear end. We make a true hollow axle for them also. The block is a true straight bore. The piston come to the top of the block unlike the Murphy ones where he has a donut at the top lowering the compression and air flow. I can make 4500 lb classes but with no weights so I usually stay out of them. Pull 5000 and 5500 and quit there. My son Brian is driving mine in this 4500 lb

12 mph class recently in Broken Bow NE. doing 13.6 mph.

 

[Trist48G]

I run a 10 inch billet crank with a 7 3/4 inch straight bore Raml Performance block and head. I pull mostly 6-8-12 mph classes with NATPA and have won points championships with it in all those classes. We cast the blocks to our specifications and then do all the machine work to them. This block reguires one of our performance heads to fit the block. The head I run has 3 inch intake valves and air flows 1040 cfm on a flow bench. The carb has been special modified for pulling that we also do. Has billet rods and custom pistons also. We are going away from the 7 3/4 inch blocks and doing 8 inch ones now. I have custom made gears in it so I run 2 3/4, 3 3/4, 3, 4, 3 1/2, 4 1/2. Takes some power to do 4 1/4 gear but have had it up to14.6 mph in that one already. Crankcase and transmission housing have been lightened as well as the rear end. We make a true hollow axle for them also. The block is a true straight bore. The piston come to the top of the block unlike the Murphy ones where he has a donut at the top lowering the compression and air flow. I can make 4500 lb classes but with no weights so I usually stay out of them. Pull 5000 and 5500 and quit there. My son Brian is driving mine in this 4500 lb
View attachment 100354
12 mph class recently in Broken Bow NE. doing 13.6 mph.

Wow that’s very impressive. Do you think you need all of those cubes to be competitive? Or could a guy do it with a small bore big stroke? I imagine the head helps a lot being able to flow so much air

 

[Tom in Mo.]

Try the pulling forum for more info

 

[used red MN]

Wow that’s very impressive. Do you think you need all of those cubes to be competitive? Or could a guy do it with a small bore big stroke? I imagine the head helps a lot being able to flow so much air

Sounds like all you need is a wheelbarrow full of cash!

 

[560Dennis]

I suggest going to the NATPA and pull your tractor as it is .
I didn’t worry about anything ,just made sure to pass tech to pull it.
When I pulled the I had it as tune up as I could get it before I went.
I took my results and compared it to the distance that my competitors were pulling . I used that to make out the budget I would need to compete with them in my weight class . That way I knew exactly what it was going to take to be competitive.
I don’t think it good idea to waste time and money on the tractor until you get a benchmark to compare to competitors.
I Don’t do anything to that tractor till i have the facts about the improvements will actually make it competitive By competition .
Have fun

 

[MSD]

Wow that’s very impressive. Do you think you need all of those cubes to be competitive? Or could a guy do it with a small bore big stroke? I imagine the head helps a lot being able to flow so much air

We have one out there that is 10 1/4 stroke with a stock block and head. The block is bored to 6 1/2 and the head is highly ported. We have a pretty good cam grind that we put in them and with that one I have seen him run with mine pretty good. 5-6-and even 8 mph he is competitive but in 12 mph he drops off. Have to remember the more cubes the more dollars it takes.