I'm rebuilding a 159 inch Case gas engine and when I was putting together the head one of the exhaust valve retainers had the springs and ball bearings fall out. Before starting the rebuild process I looked at parts on lots of internet sites and remember seeing them once but now I can't seem to find any. The guy at the machine shop is looking but did comment that the last time he did have a hard time locating some. The valves, guides and seats are all new. Are these rotators really required or are they just another gizmo that can cause more trouble than they help? Can they be gutted and used plain or replaced with the plain style like the intakes use?
- Thread starter atlarge54
- Start date
Anonymous-0
Well-known Member
In the simple term, no. But, their purpose is to allow the valve to follow its natural inclination to rotate and this helps the seat and valve wear at a more uniform rate. Their replacement isn't too hard and their value is above the cost IMHO.
K
Kruse
Guest
When I was going to tech school, our instructor had one saying: "A valve that turns will never burn". I think you need to decide if this is a parade engine or will it get hard use?
I would check to see if the parts are available from Case, check the prices and go from there.
I would check to see if the parts are available from Case, check the prices and go from there.
Butch(OH)
Well-known Member
Before that question can be answered you need to put a realisitc value on the hours you will be putting on it and at what power level. If it is something you will be operating 2 hours a week on light loads then install whatever you can most easily obtain, rotator or plain and forget about them. If your actualy going to work the thing quite a few hours then I would hold out for the rotocaps myself.
Anonymous-0
Well-known Member
I had a VW with an exhaust valve that didn't rotate. Burned a notch in the valve head several times. There they just put the rocker arm off center to rotate the valve but a burr that no shop ever noticed in the keepers I figure is what kept the valve from rotation. Might have been the rocker contact point wasn't far enough off center.
Gerald J.
Gerald J.
The machine shop called and the rotators are $40+ apiece. How do you tell if an old one is good? The only reason I noticed a bad one was the little pieces falling out during cleaning. I'm really never expecting to put this tractor under hard use, moving hay and plowing a little snow. Now if I could locate a PTO maybe a little hay work would be in the cards.
Hello atlarge54,
The reason you need to put the rotators back is that they extend the live of the valves and valve seats.
There are 2 types of rotators , positive and non positive. You clean all the ones that look good (ONE PIECE) and replace the ones that come apart or are broken.
To check them you need to do it when the engine is running. Before you start the engine you put a chalk mark on them. When you the engine is running, they will rotate/advance a bit at each valve movement. This action will keeps the seat clean. If you find that some are bad after the engine is reassembed, they can be replaced without taking the head off. A special valve tool and air into the cylinder is all you need to do that.
Guido.
The reason you need to put the rotators back is that they extend the live of the valves and valve seats.
There are 2 types of rotators , positive and non positive. You clean all the ones that look good (ONE PIECE) and replace the ones that come apart or are broken.
To check them you need to do it when the engine is running. Before you start the engine you put a chalk mark on them. When you the engine is running, they will rotate/advance a bit at each valve movement. This action will keeps the seat clean. If you find that some are bad after the engine is reassembed, they can be replaced without taking the head off. A special valve tool and air into the cylinder is all you need to do that.
Guido.
Owen Aaland
Well-known Member
Since you talk about springs and balls you have a Rotocap type of valve rotator.
The reason to use them is to rotate the valve face a little bit each time it opens to help scrape off any carbon deposits that can form on the valve face and seat. This is why the normally are found only on the exhaust valves, not the intakes. They can be checked by tapping on the end of the valve stem once it is assembled in the head. You should see the valve rotate just a bit each time the valve opens.
Incidentally, if an engine is running on propane the rotators should be removed or disabled. Propane does not leave carbon deposits and the rotators will cause increases valve face and seat wear.
The reason to use them is to rotate the valve face a little bit each time it opens to help scrape off any carbon deposits that can form on the valve face and seat. This is why the normally are found only on the exhaust valves, not the intakes. They can be checked by tapping on the end of the valve stem once it is assembled in the head. You should see the valve rotate just a bit each time the valve opens.
Incidentally, if an engine is running on propane the rotators should be removed or disabled. Propane does not leave carbon deposits and the rotators will cause increases valve face and seat wear.
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