No spark question

Last summer I installed a msd 6a in my 74 w/ a 304. I drove it around a little wih no issues and nothing but good feelings abou the upgrade. parked it and let it sit until now, as life got moe busy and important than the jeep. I finally got the time to fiddle with the jeep again and I have found that I now have no spark... I looked up how to test the 6a for spark and followed those directions and I got spark (6a module is fine) I am not getting any spark to the plugs when I crank however. When I added the 6a I changed out the cap for a new grey cap and a new grey rotor, as well as adding 8mm spiral wound wires. My question is; Should I suspect the distributor itself? Or look for a different cause? Maybe new points? not sure exactly where to go from here...
Thanks, Jake

 

Have you visually inspected points,cap, rotor, etc. for corrosion?


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Yes, no visible corossion.

 

If its been sitting, maybe the point contacts oxidized? Did you try cleaning and setting them?

 

I would suspect the points and condenser as well. You should be able to turn the ignition on (engine off) and manually snap the points open and closed, you should see a spark if they are good. No spark or very weak spark, get new points and condenser.

 

Would he still see a spark at the points with an MSD box?
Since the current carrying load is handled by the box and the points are only a trigger I wouldn't think there's enough current at the points to spark.
I would still remove the points and clean off the contacts just to eliminate that as an issue though.

 

Depends on which spark you are talking about. Opening and closing the points should generate a spark at the coil or spark plug, but no arcing at the points.

The MSD should not be picky about what kind of switch it needs to make a spark when set up for a Kettering trigger (points). You should be able to discard the condensor entirely - it's there mostly to protect the points from excessive arcing. Indeed, you should be able to simply ground the lead to the distributor and make the coil spark. IIRC this is the "MSD Test" that the OP refers to.

 

Be sure you have two wires on the positive coil lead and that the positive coil lead is hot during crank mode.

 

So I went ahead and got a net point set because on further inspection I noticed some deep burn spots (I haven't changed them since I owned the jeep) The next question is what to gap them to? Should I gap them as if there were no msd module, or is there a different gap size because they are triggering the msd?

 

Interesting question. Gramps used to use a matchbook cover. I have a feeler gauge. TSM says gap on the 4 is 0.020" and 0.016" on the v6.

Edit... No info in my book on the later 304.

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It probably does not matter much, considering how the MSD uses the points.

However, I would assemble the points and condensor to factory specs, usign a dwell meter. Then if the MSD conks out, you are ready to use the points ignition as a backup. Easy on a Delco distributor, if you own a dwell meter.

 

" Gramps used to use a matchbook cover."
A older friend of mine set my point gap on my jeep this way years ago. It worked

 

It does work. And don't call me Gramps.

 

New points gapped to .017 jeep is running like a champ... now on to the transfer case...

 

That’s a very good point. My Mallory Hyfire came with a bypass plug so that if the box ever “conks out” it can be unplugged, the bypass plugged in and the distributor then acts as it would without a box. That’s also why I kept my ballast resistor in line, in case I ever need to use the bypass plug.