Model A hand start with high compression pistons

I am rebuilding a hand start 44 A I put .045 over aluminum high comp pistons in it and getting ready to install the head that has been machined down to be resurfaced.. and I am concerned about being able to turn her over when I'm done. I don't have any experience with these 2 cylinder tractors. But I have heard of people building these tractors and not being able to turn them by hand from too much compression. Anyone have any experience with this?

Open the compression relief petcocks located beside beside the spark plugs, that is what they are for so it will be easier to turn over when you are hand cranking the engine.

(quoted from post at 06:09:16 04/29/23) Open the compression relief petcocks located beside beside the spark plugs, that is what they are for so it will be easier to turn over when you are hand cranking the engine.

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I understand the compression release petcoks. I've just heard story's of people still not being able to turn them over with them open. Doesn't make sense to me just thought I would ask before I put the head on

Have a friend who has a early 40's A that he rebuilt with alum high compression pistons and he has no trouble hand cranking it
and it usually starts on the first couple of turns.

Improper shimming of the connecting rod caps with babbitt bearings can cause them to clamp down too hard on the crankshaft and cause the engine to be hard to turn over. Babbitt bearings in connecting rods require a little more clearance than what is normal for conventional engines.

When I got my first A, a 1937 unstyled, a buddy, who was a diesel mechanic, came over one day and because the cover to the crankcase was so ungodly easy to open up, we thought that we would take a peek inside. He noticed what he thought was pretty loose connecting rods, saw that there were shims and thought we should take one out. My experience at the time was very limited, so I went along with it. Once done, I tried to roll the engine over and where it had been very easy before, it now was quite hard to roll over. So I insisted we put the shim back in even though my diesel mechanic friend was quite dubious about doing so and it has now run that way for going on 40 years. A few years later I bought a 1944 Model A. The previous owner hired a local mechanic to put in new rings and it suffered from the same problem, so I added a shim to those rods and that solved the problem there as well. Most mechanics who don't work on engines with babbitt bearings tend to want to treat them like normal engines and set them up with that kind of clearance not realizing, that with babbitt bearings, the crankshaft is suspended in a thin layer of oil and that more clearance is required.

If the mag & carb are set correctly, it should start like it did in the past.. Granted it
might be tight at first start? Bring it up on compression stroke, bleed it off & when the
impulse snaps let go of the flywheel...

I have a 36 USA with a Heisler head and the rods lengthened 0.650 inches. As long as the mag is doing its thing correctly, I can start
it by hand from my wheelchair no problem.

Would depend on how strong you are. A weight lifter type of person with big
musels would not have a problem when an average type of person could not do
it. First John Deere was a 38 A and back in 57 I don't thing they had the
high compression pistons. Dad could crank it, I could not. Neighbor could
pick up and carry a hundred pound sack of feed with each arm, my I could not
even lift one of those sacks of feed. So if one of those people that could
carry the 2 bags of feed probably no problem now like me could not do it.
Not tractor but person trying to start it. every body is not the same in
strength.