NAA Ford Jubilee Misfires

I have a 1953 Golden Jubilee that has always had a very slight missfire. sort of a puffing at the end of the tail pipe. She Uses no oil...No smoke. I replaced the distributor with a new one. New coil...new plug wires. Set the timing at 8 degrees BTDC. New Sediment fixture...New 12 volt resistor (my tractor is a 12 volt conversion) new ignition switch...It runs better at fast idle. I tried Seafoam...Tractor has plenty of power. The misfire is ever so slight. Maybe fords just sound this way???

Have you changed the plugs ?

Not being right there to listen to it I'd say (1) your idle speed is a bit too high and(2) idle mix is a little too rich.

Yes...Plugs and wires also. I put ATF fluid one quart in the oil along with a can of Seafoam. just can't figure this thing out. It has great compression, etc. Oil pressure is great also...Could it be electrical???

Yes...Plugs and wires also. I put ATF fluid one quart in the oil along with a can of Seafoam. just can't figure this thing out. It has great compression, etc. Oil pressure is great also...Could it be electrical???

As GVSII said rich idle mixture will do that, but in your owners' manual it should describe the idle as "rolling".

Sounds like burnt exhaust valve to me,but you say compression is good-is it equal in all cylinders? Could pressurize each cylinder with air and listen out exhaust pipe.Mark

You ask if the problem is electrical. Doesn't really sound like it, but a few things to check...

If you have an ohm meter, disconnect the wire from the ignition switch at the resistor. Disconnect the lead
from the coil to the distributor. Connect the ohm meter from the resistor terminal just disconnected to the
negative terminal of the coil. Should get about 3.0 ohms. If the reading is high, try reading without the
resistor. Possibly the coil doesn't need the resistor.

Another test, reconnect everything, start the engine. Put a volt meter on the resistor terminal from the
ign switch, other lead on good ground. Should read steady battery voltage, about 14 to 15 volts.

Also you can try playing with the timing. Just to say you tried, turn it a few degrees ether way, see if it
makes a difference. But don't be tricked by an increase in idle speed. Adjust the idle back down to
compensate. If the problem returns, adjusting the timing didn't fix it.

My guess is it's going to be compression/carbon problems. Have you adjusted the valves? If not, carefully
set them, then check the compression. If there is more than 10 PSI difference between cylinders, chances
are there are leaking valves and carboned up cylinders.

How about doing some diagnostics before you throw parts at it.
First thing: You say it has a misfire. OK, a misfire generally involves ONE cylinder not firing every time - or firing weakly most of the time.
Second: The things you are doing generally affect ALL cylinders - not just one.

Some things to go over:
1) a compression test will tell a lot.
2) Check for vacuum leaks. Around intake manifold in particular. A vacuum leak can cause one cylinder to "lean out" and fire erratically.
3) Spark plugs: By chance are you using champion plugs? If so, I can guarantee that you will never get a Ford to run right with Champion plugs in it. I'm not condemning Champion plugs al together, just that for reasons I will never understand, they DO NOT WORK in a Ford. Period.

There are some other things that can cause your condition, but then you are getting into major engine work. Items like a single broken piston ring. Or a poorly fitted piston. Or a bore that is out of round. Or a head that is built up with carbon to the point of significantly changing the CCs of the combustion chamber. In some cases, I have seen carbon built up to the point of hitting the piston at TDC and it would sound like a bearing knock.

Here is why I threw those parts in:
1) ignition switch was worn and wobbly.
2) distributor was badly worn in cap as well as worn out bushings.
3) Carb was sucking air from a worn out main shaft
4) Coil required a resistor

(quoted from post at 20:53:59 07/05/15) Here is why I threw those parts in:
1) ignition switch was worn and wobbly.
2) distributor was badly worn in cap as well as worn out bushings.
3) Carb was sucking air from a worn out main shaft
4) Coil required a resistor

Click to expand...

You say carb was leaking air from worn out main shaft. Are you referring to the throttle shaft? What did you do about that leak.
You say plenty of power and great compression. How did you measure those and what did you get?

I made a brass sleave to fit the Throttle Shaft then fitted it into the carb. Wall by expanding the shaft hole...Put a thin leather washer on the outside to protect it from dust. Compression gauge showed about 100 PSI with a SD of 10.
I had already ordered a new carb so I used it and put the other one up for safe keeping...i will rebuild it later...Done that plenty of times...I'm no expert like you...but...I can get her done!!!!

c

(quoted from post at 04:38:14 07/06/15)

(quoted from post at 20:53:59 07/05/15) Here is why I threw those parts in:
1) ignition switch was worn and wobbly.
2) distributor was badly worn in cap as well as worn out bushings.
3) Carb was sucking air from a worn out main shaft
4) Coil required a resistor

Click to expand...

You say carb was leaking air from worn out main shaft. Are you referring to the throttle shaft? What did you do about that leak.
You say plenty of power and great compression. How did you measure those and what did you get?

Click to expand...

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