Rachel replaced valves and rings

[Condre']

Ol' Red sometimes didn't want to start in the morning but once started would purr right along and start easily the rest of the day. One day after I took a break from mowing she wouldn't start.
After checking everything, I checked cylinder compression and got 60, 45, 40,and 35. Now that I know why the tractor won't start I am intrigued by the idea of replacing the rings and valves with the engine still on the tractor like Rachel did. Seems like it would be a waste of time and money but involves much less work. Any recommendation? Should oil pressure factor in?

[Slim140]

You’ll want to measure clearances and see if it needs a bore. If it needs a bore and you only re-ring it, that will only bandaid fix it. If you have low oil pressure it’s probably from worn bearings and bearing surfaces on the crank letting the oil pass by those surfaces.

[Eugene]

I am intrigued by the idea of replacing the rings and valves with the engine still on the tractor like Rachel did.

In tractor engine over haul can be done on the C-60 engine.

The Cub C60 engine is a small engine. Meaning it takes some mechanics tools for small engines.

For me; old age, vision distance problems, fat shaky hands, arthritis, grumpy, short tempered, ((did I leave anything out)), it is much easier with the engine on the bench or mounted on the engine stand, than laying on the shop floor.

[bofahs]

Rachel Gingell's video (plus all the idle time I have on my hands right now!) finally inspired me to do the long-needed valve and ring job on my LoBoy. Can't say enough about how helpful she was. The last engine I overhauled was back in 1989, and it was an HD Shovelhead!

A big part of my problem was valve guides - I had always had problems with valves sticking open unless I ran Marvel Mystery Oil in the gas, and eventually, even that became insufficient. Stuck valves can, and did, lead to some erosion of the valve seats. The valve stems themselves had eroded to 1/2 their diameter near the top - That's 1/4 their cross sectional area at that point, and that was going to be disastrous.

I was fortunate to be able to borrow a portable valve grinding rig from my friend James who has a Machine Shop. I ordered a new pair of grinding rocks from Gregory's machine tool supply - the valves on the C60 are uncommonly small and the grinding stones were cheap enough - maybe 30 bucks - I couldn't pass up the opportunity. Those valves were NEVER going to lap; they needed grinding.

I decided to replace the rods and pistons at the same time, and to use the hi-top pistons. The cylinders measured out at stock. The rod bearings measured out at .020 over. Remember when measuring the bearing journals, use a micrometer, not a caliper. Set the mic over-center on the journal, and gently pull as though to remove it. Slowly unwind the mic, and when it slips off, that's your measurement. I did two measurements on each journal - straight across and then up and down - to check for eccentricity, but they were all perfectly the same.

I ordered all the necessary parts - Rachel has some groupings of parts that make it easy - and a full gasket set. Yes, have a lot of gaskets left over, but I used a lot of gaskets in doing other minor repairs along the way. Like the water return hose, which I think was original 1965 equipment. I also ordered her valve guide removal and installation tools - cheap, and made a difference.

I used a straight cylinder hone instead of the ball hone Rachel uses - because it was handy. Plenty of lube, and as soon as you can see the cross-hatching, you're done. Same as the valve grinding - you can remove a lot of that old cast iron if you are not careful.

Assembly was straightforward and satisfying. Of course, where she installs a bolt or two, I had to install ALL of them!

I had rebuilt the starter and replaced the Bendix while waiting for parts to arrive. Holy cow, what a difference.

I cranked the engine through and got 95 psi across the board. That may improve slightly as the alves seat into the grinding marks on the seats, but 95 psi all the way is fine with me. Buttoned everything up, including a new China Carburetor.

When I hit the button, I thought I was hearing somebody else's Cub. Man, I've had that joker for 25 years and it NEVER sounded like that. Like a brand new motor which, I guess, it kinda was.

All in all a very satisfying and necessary job, and a great way to spend some time feeling useful during quarantine season.