JDA stroke

[Anonymous-0]

how bug of stroke can you get with stock rods? how about customs? thanks

 

[Hot Rod A]

Who cares?

If you're spending the money to stroke a crank, have a set of rods made and go big in the first place and actually have something. 9" with a 3" journal will make a nice running motor that is also pretty reliable, and will go together without any really extreme clearancing work either.

 

[Anonymous-0]

who would you say makes a reliable stroke crank.
thanks

 

[Anonymous-0]

Not so sure that a 9" crank will not have clearance issues. We only put an 8-3/8" crank in our styled A and had to cut holes in the back of the crank case and put some pans on the other side to make it fit, and we also had to grind some off of the top of the crank case. Maybe you have a different crankcase or something.

A 9" crank will make it run smoothly though and the 3" journals will be strong enough to be pretty reliable and a very good setup. It will give you a strong running tractor, thats for sure.

 

[Hot Rod A]

True, you do have to grind on the top of the case, as well as knock 2 holes in the back of the case, along with clearancing the cam...but you can't add much stroke to any 2-cyl without doing the above procedures. My point was that with a crank of that size, your camshaft is still thick enough to maintain adequate stability, as well as the fact that you don't have to do anything extreme meaning move the camshaft or change timing gears or anything, not to mention that if you're careful when doing your clearancing, you can maintain a stock appearance outside the crankcase (nothing showing or having to epoxy up between the inspection cover and governor housing).

 

[Hot Rod A]

Thats a loaded question, it all depends on who you ask...Personally I've had good luck with Merfeld, others have nothing but horror stories, the rest is for you to sort through and decide.

 

[Anonymous-0]

how much power could one expect with 9" and what about 8.375? thanks

 

[Anonymous-0]

Our A dynoed at around 60 hp. It has a power block bored out to 6-1/8" and a stroke of 8-3/8". We then put Murphy's roller rockers in it and the HP went DOWN to 57hp. The problem is that it is not getting enough air or carburator. We have a heisler head for it that we are about ready to put on it that we think will really make it come alive and give it the air and feul it needs.

 

[Frankenstein JD-A]

Does it have a Roberts cam in it?

 

[Anonymous-0]

It does have reground cam in it, but we dont know where it came from. we got the crank, cam, rods, and 6-1/8 pistons in a kit a person we know sold to us out of somebody elses tractor. we already had the power block. it runs pretty good but is always around 10 feet behind the leader. the heisler head should really make it come alive.

 

[gpuller]

Got a late A w/6.125 PB, Heisler head and manifold, big nut, stock stroke and cam that makes 60hp.
Have heard of the big A's (6.75x9) making high 80-90hp before the PTO's break.

 

[Anonymous-0]

Oh i understand. You are right Hot Rod A. A crank that size will not have any problem with clearance issues associated with the cam. cutting the holes out in the back was not that big of a deal either. It was a little time consuming and took us an entire day to do and build the pans and bolt them in.

 

[jd b puller]

Unstyled G Guy, make sure you compensate for the reduced combustion chamber on the Heisler. You could raise your compression ratio so high you'll have other problems. If it was low before, you'll be good, if it was where it was suppposed to be, you'll be in trouble.

 

[jd b puller]

Ricky, how about a new crank?

 

[Anonymous-0]

That's the problem. It only has 120psi compression in each cylinder. We had to put a 1" spacer block between the block and the crankcase for clearance issues and to make room for the stroke of the crank. We went a bit overboard with the spacing, which is making our compression way to low. The heisler head will help bring up the compression close to where we want it. If it still isn't enough then we can always plane down the spacer block.

 

[Hot Rod A]

Unst. G guy, don"t get me wrong, but those seem fairly low power numbers you"re getting for that kind of set-up. A stock crank A with a worked over heisler and high comp pistons in a 6.125 power block should get you right around 60hp, and with you"re crank I would think that your motor should be around the 75hp mark. Granted dynos all vary and if you"re running on a really tight one that would make up for some of it, but even so. I"m running an A with a heisler, resleeved power block (not a big bore though) sitting at 552 cubes and I broke the PTO on the dyno at 97hp...and the dyno is pretty accurate, dynoed various farm tractors of ours and all the results check out where they should be.

Why exactly did you need a 1" spacer plate for clearance? That motor should"ve bolted together without any extra parts, what do you have for rods/pistons?