Engine missing

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oldcubman
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Engine missing

Postby oldcubman » Sun Sep 13, 2015 11:17 am

My engine was missing so I performed the following to hopefully clear up the problem:

Cleaned and "rebuilt" the carburetor
Replaced all wiring from plugs to distributed cap and cap to coil
Replaced distributor cap with new points, plugs and condenser
Adjusted the valves
Adjusted timing

After this the engine now starts instantly but is still missing and after three hours of operation, the plugs are coated with carbon.

I took a compression test and here are the results:
1 2 3 4 Cylinder

75 75 75 75 Dry cylinder psi

82 86 80 80 Capful of oil in cylinder

When I did these tests the compression jumped up in jerks from about 50 psi or so to the final value.

I know these values are low but this tractor still pulls a plow. Do these values mean I will most likely have to change the rings and work on the valves in order to correct my missing problem?

Thanks for your help which is most appreciated.

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John *.?-!.* cub owner
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Re: Engine missing

Postby John *.?-!.* cub owner » Sun Sep 13, 2015 1:00 pm

As you said, those readings are low, and I am assuming you got them using the starter and with throttle wide open. Since the wet test only came up a little that indicates the valves need adjusted or lapping, or both. Those readings should not cause it to miss. For that you probably need to look into ignition, plugs, wires, points, rotor cap, etc. to find the problem.
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Re: Engine missing

Postby ScottyD'sdad » Sun Sep 13, 2015 1:29 pm

John *.?-!.* cub owner wrote:As you said, those readings are low, and I am assuming you got them using the starter and with throttle wide open. Since the wet test only came up a little that indicates the valves need adjusted or lapping, or both. Those readings should not cause it to miss. For that you probably need to look into ignition, plugs, wires, points, rotor cap, etc. to find the problem.

John, he replaced the wires, plugs, etc. I agree that it's likely a valve issue. Probably were last serviced, during the Eisenhower administration. If your compression tester has a quick connect on it, it may fit an air compressor fitting. Mine does. Put air pressure into the cylinder, with the valves closed, and listen for leaking air, at the manifold, intake and exhaust sides. This will tell you if the valves are sealing.
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bythepond88
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Re: Engine missing

Postby bythepond88 » Mon Sep 14, 2015 12:05 pm

You mention new plug wires, but not new plugs. How old are the plugs?
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staninlowerAL
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Re: Engine missing

Postby staninlowerAL » Mon Sep 14, 2015 12:44 pm

bythepond88 wrote:You mention new plug wires, but not new plugs. How old are the plugs?

New plugs listed in his first post, at the same time as the other "tuneup" work.

bythepond88
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Re: Engine missing

Postby bythepond88 » Mon Sep 14, 2015 4:53 pm

Oops! :oops:
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oldcubman
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Re: Engine missing

Postby oldcubman » Wed Sep 16, 2015 2:33 pm

Thank you all for your kind help!

Here is what I am going to do:

1. Test the coil since it is new.

2. Do "The Ignition Stress Test"

3. If the test doesn't fail, then I am going to pull, inspect and clean the valves and lap them. Depending how things look in the bores, I may replace the rings and bearings.

It may take a month or two, but, I will let you know how I make out.

Thanks again for all the kind help!


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