Rotating Exhaust Valves??

Thanks a million, Roper Bob

If you are doing a rebuild on the engine and you had oil pressure before, leave the oil pump alone. I wouldn't go through that can of worms until I rebuilt the rest of the engine first and ran it. That is to say, is it the oil pump causing low OP, or is it the excessive clearances in the engine?

Original motor had 3-ring pistons. If you have these, stick with them if you have to order some, go with the three rings. Mine had 4 ringers in it and they were in good shape, so I just left them in.

Piston rings are based off of the pistons you have and the size of the sleeves you put in...your call.

Two types of sleeves were used: 0.040" thick and 0.090" thick. The "40's" are the thin wall steel sleeves. The "90's" are the thick wall sleeves and should be recognizable by a flange around the top of the sleeve. If you can see the top of the sleeve and it looks to be about the thickness of a #2 pencil LEAD (not wood), you have the thick sleeves. My engine originally came with the thin sleeves, but it was rebuilt somtime in the past and bored out to accept the thicker sleeves and 0.030" oversize pistons. This is common, so don't worry about it.

As for rotating valves, it really helps to look at that section in the F0-4 manual. Normal, non-rotating valves should look the same as the intake valves when you look at the stem where it connects to the tappet. A rotating exhaust valve will look like it has an extra little cup on the bottom. The valve actually rotates inside the cup while the cup supports the spring pressure. If there's no pressure from the spring on the valve, the valve can spin and rotate freely while it is open. Again, this ONLY applies to the exhaust valves, Except for valves with mushroom stems, all intake valves are created equal. Consensus seems to be that if the tractor is going to be worked, install the rotating valves. I am just doing mine for show, so I got a new valve kit with standard valves.

As for bearings, I let the machine shop do all that. They measured the crank and journals, connecting rods and sleeves and odered the correct bearings that I needed. I think they were all 0.030" undersized. If you feel up to it, you can use plastigauge and some micrometers to figure it out yourself, but I left that much up to the professionals so I wouldn't screw something up! I want the tractor to run when I get done with it (grin)!

Hope this helps to answer your questions!

I don't know what kind of a kit you're buying, but most of the engine rebuild sets include new sleeves and as you know, there are two sizes of sleeves. Plus there was an aftermarket set of pistons for running the engine without sleeves.

If the "kit" you're buying has new sleeves you'll have to know which size sleeve you're going to need and sadly there's only one way to find out what size the sleeves in your engine are, that's by taking them out and miking them.

If your tractor has had a set of oversized pistons installed to run without sleeves that'll get you into a whole new situation. A previous owner had done something like that with my 8N, then when that wore out had someone install a set of sleeves that measured to be a little over .120". The machinist doing the work on my engine put the one sleeve he had pulled back in and then cut the old sleeves so he could install the thinner stock new sleeves w/pistons.

There's just no way, until you open the engine up and take a look and make your measurements, to tell what has been done to your tractor over the last 60 years, that's plenty of time to have been rebuilt several times. The best thing is don't take any shortcuts that you're not experienced enough to know will work, one thing I learned to hate many years ago, that was doing the same job twice. Just follow the manual and you shouldn't have any trouble. Good luck.

Mike