Sticking valves F20 update

fixerupper · Dec 6, 2018

We might have a solution for the new valves that are sticking in the new guides in my F20. I won't repeat on the net the name the machinist used to describe the supplier who supplies the STEEL guides to him. The machinist put in cast iron inserts and set the clearance at 4.5 thousanths. The book calls for 5 to 7 thousanths. Steel on steel doesn't work especially with unlubricated valves.

Mike M · Dec 6, 2018

Actually cast iron against steel is fine. You just need to watch the recommended tolerances. I worked on a lot of JD 2 cyl. I had a lot of troubles with machine shops as they were used to small block chevy engine clearances and not slow running large tractor part clearances. JD used cast iron guides in all the 2 cyls.

flying belgian · Dec 6, 2018

To unstick valves on f-20 we used to take valve cover off, start engine, spray a little wd-40 and stick a screw driver between rocker and valve. It became a ritual every spring. We only used the tractor for play during the summer. Also had to put block to hold clutch disengaged through winter or that would be sticking in spring. Ours had the Behlen road gear and was the sweetest sound going down the road at half throttle. Nephew has the tractor now and uses it to rake hay. When he inherited it I told him those two secrets. Don't know if he does it or not. I'm going to ask him next time I see him. Maybe he doesn't use it at all any more. I haven't seen him in 2 years.

jeffcat · Dec 6, 2018

Would synthetic oils work better? I know they can sqweeze their way through some very tight clearances.

JIM MN · Dec 6, 2018

Been following replies; have some comments. Clearance between guide and stem has to be .002-.004 to prevent sticking. New guides need to be reamed to get this clearance. It cleans out bore for smooth fit. Lub valve stem before assembly. Put quart of two-cycle or ATF in a tank of gas; great upper-lub for valves. If head has to come off again, knurl the valve guides if available..... This process will center valve stem in guide, you ream to fit stem in guide and process will control oil down valve stems.

rustred · Dec 6, 2018

so your saying you had steel guides installed first now changed to cast guides as should be? yes original guides are cast. guides should be lubed with AUTO TRANS. oil on assembly, as its thin. and yes should run some 2 cycle oil in tank for guide lube.

rlp in Co. · Dec 7, 2018

Since they took the lead out of the gasoline it is common for some of the older engines to have sticking valves. I had a 73 Chevy nova and a couple of small engines that I had to increase the valve stem clearance. On the Chevy I took the head to a machinist, but on the small engines I just used some valve grinding compound to increase the clearance. I learned later that some people would put some automatic transmission fluid in their oil.

36F30 · Dec 8, 2018

(quoted from post at 12:54:29 12/07/18) Since they took the lead out of the gasoline it is common for some of the older engines to have sticking valves. I had a 73 Chevy nova and a couple of small engines that I had to increase the valve stem clearance. On the Chevy I took the head to a machinist, but on the small engines I just used some valve grinding compound to increase the clearance. I learned later that some people would put some automatic transmission fluid in their oil.

The lead argument holds absolutely no bearing with the F20 as they were all built and sold as Kerosene tractors. No lead in Kerosene

Sticking valves F20 update

fixerupper

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Mike M

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flying belgian

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jeffcat

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JIM MN

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rustred

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rlp in Co.

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36F30

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