ignition timing moving

[Jim Comet]

I have been running an MDS locked out distributor, Pertonix digital 510 control box, HVC coil and have new MSD plug wires. For the last few years with this setup, I set the timing at idle to 32 degrees. But when I rev the motor to 2000 to 4000rpms the timing retarded 4 to 6 degrees. I was told this was due to the magnetic pickup in the distributor. Over the winter I installed an Innovators West crank trigger as everything I've read said this should solve the timing moving issue. I installed this and it fired right up and ran great. I then checked the timing, only to see it moving less but still retarding 2-3 degrees. Do any of you have experience with a crank trigger setup. Any Ideas what might be causing this. I set the gap on the crank trigger to .060. Thanks, Jim

[Jb427]

A friend of mine just had this problem in a circuit race 351 cleveland I will find out exactly what he found to fix it I know part of it was the pickup it was doing the same retarding ignition around 4deg too would only rev to 5k he has not raced since he got it fixed but it dose not retard now once timing is set

[My427stang]

Any chance the pickup is wire backwards?  That's the only time I have seen it unstable timing, but usually much worse behavior. 

In some harnesses, the color matches don't make sense and actually look backwards when correct.  In the end, a good way to look at it quickly, using MSD wires, is that purple should not go to purple out of the distributor. Bl;ack/orange goes to purple, and purple connects to green.

[blykins]

I have been running an MDS locked out distributor, Pertonix digital 510 control box, HVC coil and have new MSD plug wires. For the last few years with this setup, I set the timing at idle to 32 degrees. But when I rev the motor to 2000 to 4000rpms the timing retarded 4 to 6 degrees. I was told this was due to the magnetic pickup in the distributor. Over the winter I installed an Innovators West crank trigger as everything I've read said this should solve the timing moving issue. I installed this and it fired right up and ran great. I then checked the timing, only to see it moving less but still retarding 2-3 degrees. Do any of you have experience with a crank trigger setup. Any Ideas what might be causing this. I set the gap on the crank trigger to .060. Thanks, Jim

You can run that pickup tighter than .060".  I like to sneak them up pretty close.

[GerryP]

If the wires from your pickup are not twisted together, try twisting them up.  Twisting the wires together along their full length allows the wires to reject EMI through the principle of common mode rejection where the EMI affects both wires equally and cancels out.

[cjshaker]

......purple should not go to purple out of the distributor. Bl;ack/orange goes to purple, and purple connects to green.

Yeah, never understood this about MSD. It's like they purposely try to make it more difficult than it needs to be, just because they can. Match the freakin' colors!

[Jim Comet]

Thanks for all the replies, I am using shielded wire, but they are not twisted. I did make a jumper harness with reverse connections in it and per the Innovators West instructions I tried it both ways. The instructions state that whichever orientation gives the most advance with a digital system is the correct way. The engine seems to run very good in the shop. I have a data logger that should record my timing during my passes and graph it out. I am going to test on the 30th hopefully and will report how all is working then. I may order a new shielded, twisted and grounded pickup wire from MSD if the data logger shows timing movement during my runs.

[6667fan]

Jim, any other control box there you can easily swap in? The module in my locked out RTR distributor was losing degrees as the rpms went up. ( no box in system at the time)
Perhaps the brain in your Pertronix is the culprit?

The moving timing problem put me into crank trigger land also. Innovators West utilizing the 4 magnet wheel. Timing stays at 33* except for when I ask the Ultra Box to take out 20* at crank.

[Jim Comet]

Not easy unless I buy another Pertronix control box. I was very careful to route both my trigger wires (signal from pickup) and the output to coil wires separate and away from other (especially higher current) wires. Inevitably some wires do cross but do not run parallel. I will test as is this weekend and then if I still see it moving, I will get the new MSD grounded trigger wire. If that doesn't do it I will look into a new/different ignition box. Jim