I broke my engine in today. I had the engine running at 2300 rpm. I set the timing at 28* with the vacuum advance unhooked. I noticed that occasionally the timing would advance way past the marks on the balanced just for a couple seconds and then return and stay there. That I saw it only happened a few times. I kept a constant watch on the timing for this reason while also watching everything else. What would cause an issue like that? I have had the distributor apart recently and installed a FBO limiter plate. Did I do something incorrectly when putting it back together. It seemed like a fairly simple procedure. I have MSD 6AL box and am using a basic timing light.
distributor/timing issues
- Thread starter duster360
- Start date
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KitCarlson
Well-Known Member
My guess is way past the mark is not a mechanical advance issue. It is more likely a false trigger from electrical noise on pickup wires, or loose connection. The next cylinder fire would be 90 degrees, that seems to be outside of way off. The MSD has multi-spark at lower RPM, but those would be in the retard direction.
67Dart273
Well-Known Member
I think Dave, above is on the right track. MSD emits a POWERFUL spark, much more powerful than the original Mopar electronic ignition. But even the factory ECU can have interference problems
What might be happening, is the MSD OUTPUT spark is "false triggering" the distributor by electrical interference. That is only one possible scenereo.
The distributor pickup leads are "sensistive," a very very low level circuit. You need to twist them (think TV twinlead or more modern, CAT3 / CAT5 cable) and route the sensor wires NEAR a ground plane and AWAY from high power circuits.
I think MSD has "some stuff" on their site about this, Holley certainly does pertaining to their EFI. Megasquirt might. Google related to EMI (Electro - Magnetic - Interference) and RFI (Radio Frequency Interference)
What might be happening, is the MSD OUTPUT spark is "false triggering" the distributor by electrical interference. That is only one possible scenereo.
The distributor pickup leads are "sensistive," a very very low level circuit. You need to twist them (think TV twinlead or more modern, CAT3 / CAT5 cable) and route the sensor wires NEAR a ground plane and AWAY from high power circuits.
I think MSD has "some stuff" on their site about this, Holley certainly does pertaining to their EFI. Megasquirt might. Google related to EMI (Electro - Magnetic - Interference) and RFI (Radio Frequency Interference)
I noticed that when the timing would be way off that there would be a brief miss in the engine. It was not a constant miss. Just would do it occasionally. Earlier when I said a couple of seconds it most likely wasn't that long. It was just a quick miss and the timing would quickly go back to where it was supposed to be. All of the ignition system that is in the car now is the same stuff that was in it before I pulled the engine for a rebuild. It all worked fine before.
KitCarlson
Well-Known Member
Check grounds. Keep pickup wiring as short twisted pair, away from other wiring and plug wires. If the car runs fine without timing light, the timing light cables might be coupling the noise.
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