JD A looking to get a heavier class

oros35 · Jun 21, 2011

I've got a '45 JD A that pulls great in the 4500/5000lb class but runs out of juice for the 5500lb class.
I'm borderline in the 4500lb class and stripped down. Not too much fun pulling when you can't use some weight to balance it. Although it does very well in this class. 5000lb class is perfect being able to toss around a few lbs. Usually finish top 5. Most pulls around here are 4500 and 5500 so I either pull stripped down or weigh up and suck.

Motor is fresh, bored, good pistons, runs strong. Tires are 14.9 38's on 16" rims. Most tracks are heavy wet clay too.

I really feel like I need more gear. If the balance is right in 5000 it will pull till it stalls, 5500 always stalls.

Other than going with a smaller tire, what else can I do?

Can you swap the later A lower gear into my '45?

2-banger · Jun 21, 2011

you need to tune it on a dyno somethings wrong...my 50 pulls 5500 to 6500 in 1st which i knows lower than your 1st but it always spins out and its pretty much stock makes 36hp..we have pulled in 5500 in 2nd at it did well..your a in first gear should be able to pull right up to 8500lbs

JD hauler · Jun 21, 2011

you need a small arm in the old A, you dont need to get crazy, I would suggest putting in an 8.5 stroked crank, this isnt hard to do and wont make it wild, but will give you the motor you need in that class, I pulled all sorts of A's for years and ended up doing pretty well , although the one I had was quite a bit bigger. some cam work will really help to.

TiredA · Jun 21, 2011

I have been in your shoes, with a '48 A. Good runner with head work and some M&W's. Was always short on power with 14.9's. Traded it for a '51 A for its lower 1st gear. Power troubles were over with the low gears. Then I put a power block and Heisler head and manifold on it. Now I kinda wish I had my taller gears back, even with 16.9's. If your club doent allow power blocks in your "stock" class, you are probably better off to put some stroke to it. Dont know if a Heisler head alone would be enough.

Big Jugs · Jun 21, 2011

Try this first....change 1st reduction gear and pulley gear from one from a 51-52. It will gear it down some. You really won't notice it in speed, but it may gain you some extra footage.It does help. Been all thru this game....change that first...you'll prob. do it eventually even with a stroker. Big Jugs.

Anonymous-0 · Jun 21, 2011

Who says you have to weigh 5500 in the 5500 class. Try weighing about 5300 lbs. Take 200 pounds off the back. Or Make the tractor noise heavy in that class. Or just lower your drawbar about 5/8 of an inch in 5500 class.
Try this before you have to get out the check book.

MNpuller · Jun 21, 2011

I bet a 50 is close to the same power as his 45 A, stock for
stock

2-banger · Jun 21, 2011

probaly but 50 has creeper 1st thou my 60 will pull 2nd in 6500lb class got 5th place..i think 2nd in late a or 60 is equal to 1st in 2 stick a?

Josh Blackburn · Jun 21, 2011

Send me your rocker arms. You will see a big gain with higher lift. Normally they are good for 4 to 5 horse and they are cheap compared to rollers 9892775366

oros35 · Jun 22, 2011

Thanks for the replies!!

Looks like I need to see what some of these things will cost and see what the budget will allow.

jd b puller · Jun 22, 2011

(quoted from post at 14:41:04 06/21/11) you need to tune it on a dyno somethings wrong...my 50 pulls 5500 to 6500 in 1st which i knows lower than your 1st but it always spins out and its pretty much stock makes 36hp..we have pulled in 5500 in 2nd at it did well..your a in first gear should be able to pull right up to 8500lbs

Takes twice the HP to go twice as fast. 1.5 MPH (1st gear in a 50) to 2.5MPH (1st gear on the A) doesn't sound like much but it's 66% more. To put that in perspective, to have the same "umph" as your 50 does, he would need 36*1.666 = 60HP. Not going to get there with a M&W rebuild, cam grind or roller rockers.

You can throw all the cam, valve lift, etc at it you want but until you do something to actually use the air/fuel mixture (i.e. compression, you are wasting your time. Sorry, there's only so much you can do with a 5.5:1 compression engine.

As stated before, if the club allows PB's, you can bore them to 6.125" and put a high compression piston in there or a Heisler head. If they don't allow PB's, then you can get more power and look stock by putting a stroker crank in it, boring the block, using good pistons (now a cam will help) and working on the head.

2-banger · Jun 22, 2011

id call josh he just did crank..cam..rockers..pistons..block and head for my 51 a..hopefully it will be running soon. josh can get you headed in right direction and his prices are good. he also lengthened the rods for my 60 and ratioed the rockers..and the 60 runs really good

Anonymous-0 · Jun 22, 2011

an A like his would power out in 4500 on our circuit. If you want to pull you need a horse not a pony.

39 A · Jun 22, 2011

I concur on calling Josh, he worked on my head, did some ratio rockers, re did the carb, and legthened my rods and it really woke my tractor up, he is very fair and does a great job.

JD A looking to get a heavier class

oros35

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2-banger

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JD hauler

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TiredA

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Big Jugs

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Anonymous-0

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MNpuller

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2-banger

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Josh Blackburn

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oros35

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jd b puller

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2-banger

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Anonymous-0

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39 A

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