Electronic Distributor Trouble

[I8URACING]

I am having problems with my electronic distributor. When we were getting ready for the feature on Saturday we didn’t have any spark. I found the problem to be the gap between the reluctor and magnetic pick up was too big. We adjusted the gap back to .008” and had good spark. I had adjusted this about a month ago and was surprised to find this problem, as the adjustment screw appeared to still be tight. The advance assembly seems to be kind of sloppy by design.

I am using a factory vacuum advance distributor without the vacuum port hooked up. Is there a modification I should be doing to the distributor to better hold that magnetic pickup in place? How big of a gap should I be able to have between the reluctor and the pick up and still get signal to the ignition module? Is the pick up possibly bad? I am using a chrome ignition module.


I thought about buying an aftermarket distributor but the rule book states: “Distributors Stock O.E.M. distributors only. No bullet distributors allowed. No multiple-spark boxes. No magnetos or dual-point distributors allowed. Any coil used must fit in stock cap and must use stock coil cover”

Obviously the rule doesn’t complete apply but I think its clear that I have to use a stock distributor.

Any suggestions that you have would be greatly appreci

[340king]

MSD ignition offers some technical advise in some TB's. They used to package these with some of their stuff. One such TB dealt with the phasing of the distributer. It talked about getting the relucter lined up with the corresponding post on the distributer cap. This is called distributer cap phasing. I have done this two different ways.

One way to do this is to take an old cap, drill a hole into it about a 1/4", in line with a post on the top of the cap. Then start the engine, placing a timing light on the wire leading from that post. Shine the light through the hole and try to center the rotor in the hole, by moving the vacuum advance plate in or out. Once you have it lined up, weld it into place with JB weld or by actually welding it. Verify that the phasing is correct after this operation by repeating the timing procedure.

The second method is less invovled. Scratch a witness mark on the outside of the distributer that corresponds to a pole/wire socket. Then witht he cap off, line up the relucter and center the rotor on the witness mark by moving the vacuum advance back and forth. Once centered, weld/glue the vacuum advance plate to the breaker plate.

Both methods have worked, the first should be more accurate as it takes into account any dynamic changes in the distributer. This ensures that the timing isn't moving around due to advance plate movement.

I should probably tell you why I want you to do this. Usually the air gap will vary slightly over the range of movement of the vacuum advance. This can cause problems like you mention. Typically, they don't completely lose the gap though.

[daren44]

That's interesting. I have a 360 that the timing seems to jump around some. I have a stock vacuum advance distributor. At idle, the timing varies as much as 5 degrees either side of about 8. I have light springs in the distributor that quicken the advance curve. At full advance, 35 degrees, the timing mark varies about a degree, maybe 2, either side of 35. And the mark doesn't stay in view all the time, it disappears once in a while. It's really erratic. The car runs good, don't have a problem there. Used the same light on another car and it was rock solid. Tried the distributor from that car and it did the same thing on my car. What gives?

[Buddy]

Daren44, is the ring on your harmonic balancer tight? I wonder if it could be moving a bit, giving you false readings. Just a thought...

[daren44]

I may have the trouble pinpointed. Saw on the MSD site that MSD ignitions cause trouble with some timing lights, especially the ones with the adjusting knob. Mines a cheap one with adjusting knob, so that is probably it. I'll find another one and check it. It almost has to be that because the engine runs good, except for the new miss I've gotten.

[cageman]

Welcome to running a timing chain. That is probably your erratic timing.