Super C oil pressure

My Super C when first started runs over half on gauge when run for a little while it drops to around quater of gauge no rattle that I can hear from being low. Any help Thanks in advance.

If by a quarter-gauge you mean just out of the red zone, and that's at half throttle or better after the oil has warmed up and thinned out, meaning also that the gaps in the main and rod bearings have opened up, too, I expect you want to be keeping a thought about some some new bearings and maybe a crank grinding to go with it in the back of your mind.

Prior to that, I'd suggest a couple of things much less extreme. I don't know how many motors you work on, but between my own and the neighbors, I've found it handy to have an extra gauge around as a test gauge. Unless you have a new gauge on there, it might not hurt to buy a decent oil pressure gauge (I got a Stewart Warner for pretty reasonable at NAPA) that reads in psi. Thread it on in place of the one you have (it's a 1/4" NPT thread) and see what you have. The drop in pressure as the motor heats up (gaps open, oil thins) is normal, but it's good to know what kind of pressure you actually have. The needle may swing more than the Rochester gauges, so go by the reading, not the swing of the needle. The relief valve on the pump is set to kick in at 50-60# so something in the 50 range =/- 5-7 when warm is fine.

If it is low at half throttle and above, then you need to have a look at your oil pump, which is a matter of dropping your pand and removing two bolts. A clean screen on the pickup is obviously a good idea (as is a clean pan!), but it may be the shaft and cover are worn so that the end play is costing you pressure. Search on oil pump in this forum and you'll find all manner of threads on how to evaluate that.

It may still be your crank bearings, but I'd eliminate these two before I started after the crank.

A more likely problem on this engine is a warped oil pump cover. They are made of potmetal and warp easily. Search the archives, been many posts on this topic, some by myself.

Swap in a known good 0 - 45 or 0 - 80 gage and see what the actual pressure is.

With the oil fully warmed up, so long as the gage shows a minimum of 15 psi at speed and is at least a couple psi (gage hand is off the 0 pin) at idle I wouldn't be terribly concerned - especially if you don't plan to work the tractor hard.

As the others note below the cause could be a warped oil pump cover (easy to fix) or worn bearings and/or crank (more expensive!).

Incidentally switching to 15W-40 oil usually increases oil pressure by a few psi in an engine with a worn bearings and/or a tired pump. You might give that a go and see what happens.

Incidentally also I purchased my Super H for a good price on account of a "chronic low oil pressure" problem. The "problem" turned out to be a stiff, worn-out gage...

That should be 1/8" NPT thread on the back of a test gauge. That'll be a lot easier to find at NAPA than 1/4".

Sorry about that. Not sure what I was thinkin'!