MSD box and coil trouble

[Guest E.Murray]

When I bought my 260Z with the SBC, it was hard to start and ran a little rough at higher RPM. I pulled a plug and cranked it and the spark was a pathetic little yellow thing. To fix this, I went whole hog and got an MSD6AL box, a Blaster II coil, Pertronix Ignitor II, and new cap, rotor, wires, and plugs. It made all the difference in the world. The spark was big and bright and the car started with one quick turn of the key. All was well until a couple weeks ago when the car started running like crap again. It was hard to start and ran a little rough at higher RPM... sound familiar? I pulled a plug last night and the spark looks terrible again. It still runs, but acts like I'm back with the old non-MSD ignition. It would seem to me like if the box or coil went bad, it wouldn't do anything at all. Anyone have any experience with these units to know if they can go bad and sort-of quit? My guess is that the box is the culprit. Any other ideas before I have to shell out another $200?

[JMortensen]

Never had one go bad, but from the people I know who have they all said it just quit entirely, no sputtering or anything.

 

Couple things to check:

Gap on the Pertronix sensor. I assume it needs a gap to the trigger wheel. Not sure what it would be, but I've seen that cause problems on 280Z optical trigger ignitions.

 

Plugs, cap, rotor, wires. All of these things can cause the problem you're seeing.

 

Connections. Make sure the wires are all firmly connected to the cap and plugs, and that all connections for the MSD are tight.

 

Last thing is MSD has a warranty. They also have a servicing fee. I want to say it is $50, and you send them your dead MSD and they'll test it, diagnose it, and fix it.

 

Also Dan Baldwin had a weird one a couple months back where the pertronix trigger wheel had a piece coming off of it. He found the piece and epoxied it back on and that was the fix. That situation affected just one cylinder IIRC. You should be able to search and find his thread.

[fastzcars]

I had problems withe the blaster SS coil. A friend and I bought them at the same time and place, and they both went out within a week from each other. We took them back and got the blaster HVC coil. You know the blue one with the large heatsinks the partno is 8252. Never had problems again. I would change the coil first.

[Guest E.Murray]

I was blaming the box or coil since the problem doesn't seem to affect just 1 or 2 cylinders, so it must be "further back" in the system. I went to MSD's website and it looks like they have a pretty good tech support group and forum. Some searching turned up what I expected - the parts usually just go entirely. Back to square one... Actually, the Pertronix never even ocurred to me. Maybe that is the deal. I'll pull it apart (maybe put the points back in, even) and see. Thanks for the great help.

[ezzzzzzz]

The Petronix is merely a triggering device. The MSD creats an extended high voltage discharge across the plug via the coil. The coil produces the high voltage. I'd check to see if there was a full 12 volts to the coil and then maybe consider swapping out the coil. Another issue can be carbon tracking in the cap due to the higher sustained voltages, bad rotor or even a damaged carbon button in the cap. I'd look at the simpler possibilites before writing off the MSD box or coil.

[Guest bastaad525]

when my first MSD 6A went bad it didn't quit all at once, I started having problems with it not wanting to start, getting worse over the course of about a week or so, enough that I'd crank until the battery got low and the starter would barely turn... eventually I figured out it was my MSD when I removed it and the car fired right up.