74'/350 Eating Points

[Robert S.]

I have getting only about 1000 miles out of a point set. Although I did not buy the car new, the ignition system appears to me to be the same basic configuration as when the car was built. Last point set installed (Uniset design purchased at Napa that I just replaced due to a no start) had almost all of the point material gone. It started right up when I installed a new set of points. Each installation I set the dwell to 30 degrees with a dwell meter. Engine is stock - 195 HP.
Any thoughts as to cause? - I should be getting ten times this point life.

[Steven B.]

Re: 74'/350 Eating Points

Robert, some areas to check; Are the points set too close? Is the condensor OK? Is the coil OK and the correct one? Too much current and/or points set too close can cause premature burning/pitting.

[Duke W.]

Re: 74'/350 Eating Points

Could someone have bypassed the resistor wire? This would cause excessive primary current, which can burn the points. Did you buy Echlin brand from NAPA or their cheapy no-name brand, which I think is "Mileage Plus".

With the engine stopped, points closed, and ignition on measure voltage at the + terminal of the coil and the same with the engine idling.

Also measure the primary resistance of the coil and state the brand and part number.

Post all the test data here.

Duke

[Steven B.]

Re: 74'/350 Eating Points

Are you getting a constant 12V? Follow Duke's procedure.

[Robert S.]

Re: 74'/350 Eating Points

Replies to questions asked: Points installed were Echlin and appear 100% identical to the worn out points removed which I also got at Napa. Coil is a typical black Delco Remy coil that says Delco Remy on the top but do not know part number. I measured the coil resistance with an old Simpson type meter and got about 5 ohms and meaured it again with a more modern digital meter which read 2.2 ohms. Engine at idle running - 11 or 12 volts on positive side of coil. With engine off (don't know if points were open or closed) I got about 8 volts. This seems backwards from the way I think it should be. Positive side of coil has a black wire and a cloth covered grayish wire both from the harness and the black wire from the condenser. Negative side has the one wire going to the points. Engine starts well and runs normally with no obvious ignition issues.

[Dan H.]

Re: 74'/350 Eating Points

Robert, how do you lubricate the cam? I would use cam lube smeared on the cam. Sometimes the wicks don't do a adequate job. Had a set close up on me while using the wick thing. Also, assume your cam lobes are in good shape. See if your old point rubbing block is worn down compared to new ones.
Dan

[Robert S.]

Re: 74'/350 Eating Points

I believe the distributor is original to the car which has 32K on the odometer and as best I can check registration records is likely accurate so I do not think the cam is worn. I used the grease that came with the points to lubricate the rubbing block. I saw a little wear on the rubbing block of the points I removed but not much. The main issue is the contact points are shot after about 1000 miles which I guess means the current flow/voltage across the points is too high but assuming that is true I do not know what to do next to troubleshoot.

[Duke W.]

Re: 74'/350 Eating Points

Engine at idle running - 11 or 12 volts on positive side of coil. With engine off (don't know if points were open or closed) I got about 8 volts. This seems backwards from the way I think it should be. Positive side of coil has a black wire and a cloth covered grayish wire both from the harness and the black wire from the condenser. Negative side has the one wire going to the points. Engine starts well and runs normally with no obvious ignition issues.

Do the voltage measurement again engine off, ignition on and use a jumper to short the negative coil terminal to ground. This is equivalent to the points being closed. I agree that the engine running voltage at the + coil terminal should be less with the engine off and the points closed.

Coil primary resistance is in the ballpark, but check against spec in the CSM.

Check the resistor wire resistance as follows: Disconnect + battery cable, turn ignition on and measure resistance from + battery cable to + coil terminal... should be about 1-2 ohms.

The + coil should also have a wire from the S starter terminal. This shorts the resistance wire during cranking to deliver full battery voltage to the coil. My thought is that if the S terminal gets shorted then it shorts the resistor wire and delivers full system voltage to the coil all the time.

If you have an ammeter that will handle at least 5 amps get a current reading of the primary circuit with the engine idling and off.

Inspect the points and determine if material is being transfered from one side to another. This can indicate a condenser issue.

Duke