TO-30 was running good now not so much

[haysaver]

I have been running the tractor last couple days and was running good. Drove it two miles today and it started to skip. This tractor has been changed to 12 volt. New wires , new plugs , good spark at the plugs. Good flow of gas to the carb. I feel like its carb related but messing with the idle screw has no effect. It does run at idle well. I think next thing to do is a carb kit. I did take it off and took it apart to see if there was crud in it but found none. I am stumped??

 

[RM-MN]

How did you determine that you had good spark at the plugs? Pull them out and lay them on the engine and look at the spark? The proper way to check for that is with a spark gap tester. If the spark will not jump 1/4 inch in air it won't reliably jump the spark plug gap when under compression. That can get you a poor running engine.

 

[haysaver]

ok. I don't have a tester but can get one. I took the points off and they look burnt. that is the second set althou not new ones but they were good when I put them in. I have a temp gas tank on it now with no change. took the plug out of the bottom of the carb and have steady gas flow. Coil is 12 volt and new. Neg. to distributor as per diagram no resistor. What has me puzzled is it was running fine and all off a sudden crappy. I checked for a wire that had rubbed found nothing. I have not removed the distributor but took the mounting plate out and cleaned und best I could. a little rust but not bad. A little play in the shaft but not enough to alter the points I feel.

 

[sunbeam]

If the points are burnt I try a resister

 

[Steve@Advance]

Doesn't sound fuel related. Did you take a fuel sample from the carb drain? Was it clean, free of debris, rust? Ethanol gas with water will appear cloudy. If the carb was clean, a kit will likely not do much if anything.

The idle mixture is only adjustable at very low RPM, down around 400. Turning it in richens it, out leans the mix. The screw adjusts air bleed, and has very limited effect on the mixture.

I would be more suspect of the ignition.

The coil, are you sure it is a true 12v coil? Two ways to tell, take it out of circuit, check the resistance across the primary terminals. Should be around 3 ohms for a 12v coil. Or ground the - terminal, series your amp meter from the + terminal to the battery, should get around 4 amps. Reason for testing, coils are often miss boxed, not well understood by todays counter people, easy to have the wrong coil.

Points and condensers, often bad out of the box. Poor quality across the brands. Points are very susceptible to any abnormality. Wrong coil, bad condenser, worn distributor shaft, wrong gap, surface contamination... The contact alloys are poor, any number of reasons will cause premature failure.

Watch the points as the engine is cranking. There should be very little visible spark. If the points are throwing intermittent yellow sparks, not good. Also you can put a test light on the points side of the coil, it should have a definite off-on signal each time the points cycle. An irregular flash, or dimming light means poor point connection.

One other test, connect your volt meter or test light to the ignition side of the coil, wiggle the ignition switch and related wiring. Watch for the light to dim or voltage to fluctuate.

I have had very good results with the point eliminator electronic ignition kits. They will work with a less than perfect distributor, but the centrifugal advance needs to work. It is a good alternative to todays poor quality points, but still requires the right coil, and will not solve other spark related problems.

Also visually inspect the cap and rotor. Look for signs of moisture or carbon tracks. Be sure the carbon piece is intact and contacting the rotor. If you replace the cap and rotor, compare the new with the old carefully. Common for them to be miss boxed, wrong construction.

You can make a spark tester from an old plug. Break the electrode off, connect to a plug wire, ground the base. Should jump a blue hot spark to the grounded base.

 

[Paul V B]

Yes try a resistor. I have one on my 12v Oliver and TO 30

 

[54FergieTO30]

I don't have much confidence in new condensers. I am no expert, but just changing the condenser might be a place to start.