Point Longevity in Case 4 sylinder tractors.

Paul f · Sep 20, 2015

A young friend has a Case 311B and a 530CK (gasser). He has owned them about 3-4 years and in each instance we put in new ignition parts when he got them. Last fall the 311B acted up and upon examination found the points had worn away to the point the movable arm metal stamping was the only thing making contact. The fixed side wasn't too worn. Yesterday his 530CK failed, same issue. The contact on the movable arm was almost completely gone the fixed contact not so bad. I got worried about my VAC which has a similar distributor (if not identical uses same points) and looked at it. The contact on the movable arm is just about gone. These are older but she is only used in the summer with a finish mower. Points were i believe either TISCO, Standard Ignition and maybe one was NAPA. Is it normal for them to be eaten up so fast??? The rotor cap and spark plugs are still good on all three tractors...

oldproudvet · Sep 20, 2015

My 310B is 12 volt (gas) you have to have a functioning ballast resistor in the primary circuit. This will either be built into the coil, at which point, it will be stamped or imprinted as internal resistor, or an external which usually looks like a small porcelain brick, maybe 2" by 1". Many times, over the years coils are swapped. If you have 12 volts @ the primary lead, going into the distributor, you have an issue. Otherwise, and not so likely, it's a grossly mismatched condenser. It must be matched to the primary coil windings. In today's world, numbers are combined, and the only difference is the lead or connection out of the condenser. The capacitance is measured in micro-farads and is listed in any good tune-up specs

Paul f · Sep 20, 2015

Thank you ...Good point about the 12 v and needing a ballast resistor. I know his 530 is 12v and I am guessing so is his 311B. My VAc is 6 volt and the points have been there for much longer..8 years or better. Guess I should get him a ballast resistor.

rvirgil_KS · Sep 21, 2015

With points open you will see 12 volts on the coil to distributor wire.

Six volt coil (or 12 volt, external resistor required) will read about 1.5 ohms across small primary posts on coil. Direct 12 volt coil (no resistor required) will read about 3 ohms.

With points closed, on direct 12 volt coil you should see near battery voltage on coil input and 0 volts at distributor.

With 6 volt coil and ballast resistor, points closed, you should see near battery voltage at input to resistor, 0 volts at coil to distributor, and about half battery voltage between resistor output and coil input. With points open you should see near battery voltage on both sides of resistor and coil.

Points don't care if they see 6 or 12 volts, they care about the current passing through which is controlled by the resistance of the coil/resistor combination.

Point Longevity in Case 4 sylinder tractors.

Paul f

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oldproudvet

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Paul f

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rvirgil_KS

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