Here's the story. This weekend had an auto X. Car had been running oddly everyone once in a while before after long cruises. It would run up and down in rpm and sometimes die. Then would start up afterwards without issue. Any way went to run was in first gear for the first half of the run. Car just putters out. Put in the clutch and out again start the car while rolling. Now its running extremely rough. First thought is I blew it. I had pulled timing before the auto-x and was running rather rich high 10's at 10 psi. Anyway, roll past grid and pop the hood. I pull one leading at a time doing a quasi compression check. Nothing sounds odd. Plugs are fouled beyond anything I have ever seen. They were new but only a few hundred miles earlier. Anyway car would idle but extremely rough around 500-1200. Start thinking its ignition. Pull the leading plug coil input and start the car. Car runs the same as when plugged in. Checked compression tonight ~110-115 front and rear across all faces. Well after that checked the resistance on the main coil got 0.9 ohms at the harness and could not get a resistance across the plug terminals. I know I should be getting something. So I tried for about 10 minutes to make sure I was making contacts correctly, and get nothing.

So I'm wondering is this the normal failure for the main coil? Should I still be getting resistance across the harness part of the coil if its failed? Anyway, my harness fell apart as I was messing with it so I'm trying to decide what to do and what to test. I am running an MSD 6a and I know serveral that have had those fail. My thought is to go with the MSD 8204 with my 6a if its ok. As the plug harness is broke off now. Any other suggestions?

Thanks

 

Anyone have any thoughts, I've gotta get parts ordered soon. Also does anyone have the part number for the ignition harness?

thanks

 

You should be aware that some of the wire in the FD coil harness--on the leading coil primary is resistance wire so it will affect you readings. I don't recall if you can get a reading of the coil's secondary because there may be an internal capacitor in series with it.

BTW: The best way to measure the coil is by inductance, if you have the capability to do that. I posted the correct values elsewhere in this forum a while back.

Have you jumpered the MSD out for a comparative test?

I currently have one on my FD's leading coil and have also used MSD 6A's for over 20 years on everything with good results... They will get unhappy, however, if they overheat or get water in them.

 

I pulled resistance values directly from the coil not through the wire. Also the plug outlets (leading to leading) did have a value of 9-16 ohms if I remember correctly in the manual. This is the test that I could not measure any resistance on. Not sure if there is any other way to test it. In order for me to jumper it I will have to do some wiring work as my harness fell apart as I unplugged the connector. What really pissed me off is that I know how crispy these guys were and it still broke one of the wire's right at the connector. To be safe I beleive I will order the ignition harness too.

Does anyone know if they motorcycle two terminal coil from MSDS can fire straight from the FD's trigger. Or will it require a 6A in conjunction like an FC coil? Also is there a test to determine if a 6A is good without a coil?