51' H - running rough

bmagee · Oct 31, 2010

Need a little help. got my granddad's 51' running. I have changed the points, plugs, condenser, cap, rotor and wires. It still seems like it has a plug wire off.

Any advice?

It had not run for about five years, but I have it cranking with the starter and it fires right up, just a little rough.

Thanks

Janicholson · Oct 31, 2010

It probably has a stuck valve. Easiest check: Pull the plugs out and with a little help, (and in neutral) have someone crank the engine just a few turns with your thumb covering the spark plug holes, one at a time. If one hole has no or little pressure, It is probably that cylinder. Pull the valve cover off and you will probably find a valve that is open, with the pushrod laying disconnected.
Spray a penetrating oil on the underside of the keeper where the valve stem enters the guide, then tap on the top of the valve with a plastic hammer.
Peck at it, do not pound. It will probably begin moving, and spring back closed. Put the pushrod back on, and adjust the valves to .020 cold. Then put it back together temporarily and adjust the valves when warmed up to .017".

Probable cause. Jim

old · Oct 31, 2010

You say it had not run in 5 years. Did you do anything like put ATF in the cylinders etc to clean up the rust that has to be in the cylinders and to free up sticking rings etc??? If you did not then it could be sticking rings a sticking valve of a number of other things. Even having the points set wrong can do that. When I have one do as your is I check point gap on all the lobes in the distributor since some times you have one that is not letting the points open like they should. One fast and cheap way to figure if it has a valve stuck open is do the thumb compression test pull the plugs and with your thumb in the spark plug hole see if it blows your thumb away when you spin it over. If you have a stuck valve that cylinder will not blow your thumb off

Brownie 450 · Oct 31, 2010

Are the plug wires in the distributor cap correctly?
2 1
4 3 looking at the distributor cap from the rear of the tractor.

gene bender · Nov 1, 2010

Take your timing lite and go from wire to wire checking for spotty spark this will show a bad shaft bearing in the dist bad wires bad cap ect.

bmagee · Nov 4, 2010

To those who replied - thank you very much for the help and advice. I took valve cover off last night, the exhaust value on cylinder #2 was open. found pushrod loose as described. After a bit of PB Blaster and a few taps, it worked free. All valves were checked for .020 and put back together.

It started right up and runs as great as it always did.

Again - A BIG THANK YOU!

51' H - running rough

bmagee

Member

Janicholson

Well-known Member

old

Well-known Member

Brownie 450

Member

gene bender

Well-known Member

bmagee

Member

Similar threads