Super A rebuild - How would you do it?

I have a '51 Super A that I inherited with a freeze crack from front to back on the left side (I hear it's a common problem). It was working ok for a while, but took to blowing oil from the head gasket and leaking anti-freeze from the bondo patched crack. It was also blowing compression into the crank case, and oil fowling plugs, so it really needed a major anyway - but not with a trash block.

I located a sound block, stripped and boiled for $500, and wonder how those who have 'been there' before, would do it from the ground up: High compression pistons? Flat tops? Standard 3" bore? 3 1/8? Are hardened valves and seats available for no-lead fuel?

Anything else you might think of?

I figure if I'm gonna do it, I may as well do it as right as I can.

Thanks in advance.
Well Worn

well worn, id look at it this way ; the old girl has just lasted 60 years in stock form, the freeze crack being a human error, not the tractors doing, if it were mine , id go back factory stock,unleaded fuel has been around since the mid '70's and she didn't drop a valve yet, hardened seats would ne nice however if there avalible, if not the replacing them with originals will probably make it another 60 years and will probably last longer than almost everyone on here will be around to care, remember the more hot rod tricks you do to it, the sooner ya got to do it again,

3-1/8" High Compression pistons will give you a nice increase in power for very little expense, I would do that.

If your valves are OK I would not go to the expense of hardened seats unless you are replacing them anyway.

Some time and money spent going over the governor is well worth it. Fix or replace anything that is worn, loose, or broken inside it. Then set it up per the manual. A smooth, responsive governor makes a tractor a pleasure to run.

If you're going to work her hard and need extra power then go with the high comp. pistons. Otherwise I would just go with standard with the 1/8" overbore. I used the 1/8" overbore on my A and she now has 20HP (they were tested at 17 new). Hardened seats can be expensive and if she won't be worked too hard its not really worth it. Definately grind the valves. Be sure to seal her up real good. The aluminum blocks on the front and back of the motor around the crank like to warp and will leak. Lay them flat on a piece of sandpaper on a bench and sand em out till they sit flat on the bench.

Thanks for the input, gentlemen.

Ericlb, it was my understanding that unleaded gas doesn't make engines drop valves - that it was more a mechanical problem of broken springs; over revving, floating and smacked valves on dome pistons, popped keepers, or a rare 'stuck' valve on an engine that doesn't see much use. Methyl ethyl lead slowed the explosion rate, making cheaper (low octane) fuel possible, and a slower, cooler burn. The faster combustion rate and resulting higher heat of unleaded 89 or less octane fuel tends to 'burn' the edges of exhaust valves and seats, causing compression loss and aggravating the problem as hot (just ignited, highly compressed) combustion gases start leaking through the pitted valves and seats, especially in higher compression engines. Is it possible that a very long term of such abuse could cause a catastrophic valve failure? I suppose, but such an engine would barely run, if at all.

RedDave, the governor is definitely loose in the joints, and that was already on the fix list. Are there specific wear parts in it that should be replaced? or is it best to use a 'shotgun' approach, and replace 'em all?

RFB, thanks for the tips.

I'm thinking that the flat top pistons might be better with unleaded fuel and OEM type valves, even with the 1/8 overbore, which I think I'll do. As was pointed out, it's done ok for at least 25 years with somewhat unleaded fuel (I've been using lead substitute in it, but no guarantees what went on before I got it). Also, might help to retard the timing just a hair from factory spec to compensate for the 'ping' of a faster burning fuel, and get more umph from the bang as well.

Also wondering if anyone has ever come up with a lower first gear set up? I'm sure I'm not the first or only one to think it would be handy to slow it down just a little bit.

Are standard 3" sleeve kits available for the C113 or are all the available sleeve and piston kits 1/8" overbore?