Left Me on the Side of the Road! Now What?

I just replaced my MSD cap for that very reason, they do seem to dissolve

 

Had the old style MSD box go bad. Every once in awhile the car would stall. I'd open the hood smack the box and then the car would start.... Until one day it didnt any more. Got the newer digital box and no more issues

 

Definitely not that. Checked and it's good.

 

More likely, a magnetic pickup. Hall-effect switching is a TOTALLY different technology.

Didn't you already diagnose that the MSD box is flaky?

The coil sparks. Not conclusive proof, but a really-good sign. The mag-pickup passes the ohms test. Not conclusive proof, but a really-good sign. The spark-box was dead the first two times it was triggered. Not conclusive proof, but a really-bad sign.

Tells me that the primary suspect in this case is: MSD box. There is an outside chance you have an intermittent somewhere in the pickup-coil circuit, or a fault in the ignition coil, or a fault in the wire harness connecting all those parts, or maybe even multiple failures. HOWEVER, you've almost certainly got a problem in the spark-box. In MY driveway, the first thing I'd do is replace/bypass the MSD spark-box, and see what happens.

No idea why you'd use components that are as likely to strand you as the MSD.

You own an HEI. That's your solution. OEM reliability--probably THE most-reliable electronic ignition system ever produced, until it wears-out and needs to be refurbished. Once rebuilt with quality parts (Not Communist Crap knockoff parts) including a low-resistance button between coil and rotor...THE most-reliable electronic ignition system ever produced. Every weak spot in the design has been upgraded, (early modules, early 2-wire ignition coils, early black rotors, wear to the centrifugal weighs and pivot pins, and the carbon button between the coil and rotor) Every common failure mode is well-known. Common parts are as close as the nearest parts-store.

Or

Use your existing "small body HEI" to trigger a genuine HEI module. Preserves your timing curve, and again you already own everything you need except perhaps a heat-sink to mount the module to, (Doesn't Dave Ray mount the module to the underside of the distributor housing? You'd need to drill and tap two holes. Maybe Dave has done that already!) and some wires connecting it to the distributor and ignition coil. If the ignition becomes reliable again, you've validated the pickup coil and ignition coil.

 

OK, I think I have definitely diagnosed it to be the MSD 6AL barring any other issues.

I swapped coils. The Blaster 2 had 1.0 ohm and the stock-ish one showed 2.0 ohm. I started it and backed it out of the garage. It died while I was looking at things and wouldn't restart. I immediately pulled the mag pickup trigger and with the key on, it will not spark the coil. The magnetic pickup still showed 560-ish ohms.

I put it all back together and it hit a couple times but wouldn't continue to run. Now, I just have to wait for it to cool off enough I can get it back in the garage.

Question: What else can I do with the magnetic pickup? Does it require an MSD or is there something else that will work?

I'm home now but if it ever happens again, I'd like to have something quick and easy to get it home. I know I could put points in it but that seems like a lot of roadside work.

I also found my old Mallory Unilite distributor that was in my old engine and the MSD5200 that it ran. Not plug and play with the 6AL though.

 

There was a time--about 1979--that I had a Unilite and an MSD5. Worked fine.

Eventually the Unilite went onto a boat, and when I came back the next year, someone had had to replace the distributor because the Unilite died. I've seen too many dead Unilites to recommend 'em. Mallory expects you to buy a protection device for the Unilite module that costs as much as a new module. Should have been designed-into the Unilite module to begin with, not an extra-cost add-on.

Just use the HEI module.

 

I *REALLY* don't want to have the HUGE HEI distributor in there if I can avoid it. It offends my asthetics on a 70-72 car for some reason.

On the Unilite, I ran it for 30 of the years I've owned the car. I only swapped because I upgraded to the 6AL and this distributor with the new engine that I bought from a board member way back when.

I could just buy a digital 6AL and be done with it. Or, I'll convert to some non-points ignition to keep my cap and distributor like I like it.

I'm really wishing the Fast XRi was reliable. They have gotten a horrible reputation since Crane sold them.

 

Anyone used one of these? Claims to be more rugged than the 6AL and lifetime warranty, which is only as good as the company, if they stick around.

Intellitronix 150

 

That is kind of spendy, but does look legit. Let us know if you try it ;~)

Upon further review I see that's cheaper than a 6AL!

Yikes.

 

Yep, and even cheaper on eBay. I'm going to wait until I get my car apart and can verify all the wires were intact and not something easy that is hidden in the wiring harness.

 

PUT
THE
HEI
MODULE
UNDER
THE
EXISTING
DISTRIBUTOR,
ATTACHED
WITH
TWO
SCREWS
AND
SOME
HEAT-SINK
COMPOUND.

You wouldn't have to use the bigass HEI distributor. You have a small distributor with a pickup coil. Staple the module to the underside, and route some wires from pickup coil to module, and from module to coil.

Or put the module somewhere remote from the existing distributor, attach it to a heat-sink, and use longer wires from the pickup coil to the module. You'll want to twist the two wires together, or have them in some sort of shielding to prevent RFI interference.

 

I am not 100% sure what is under the cap. It may not be an actual HEI pickup but just an MSD hall cell module to trigger the MSD 6AL.

 

Almost certainly not a Hall-effect device. Just about guaranteed to be a magnetic pickup. I think Dave uses Ford or "MSD" style. When I did it, I used a Mopar reluctor and pickup.

 

Yep, that's what mine looks like under the cap. I can't imagine the star wheel went bad and the pickup registers the proper ohms.

The video is me triggering the coil with a momentary switch. It took 3 dead tries before the 4th one fired. I can also here a very definitive clicking inside the MSD box like a relay closing with each trigger. Anyone know if that is normal? Does it perhaps have to detect a certain RPM before it will begin to fire?

 

Update: Someone on FB (I know, geniuses) suggested it needed full 12v, not the old coil+ wire as listed in the diagram. I jumped 12v to the power lead and it still takes a few triggers to get it firing even with full battery voltage.

Once it starts firing it will continue to fire. If I turn power off and wait a few seconds and turn it back on, it will again require a few triggers to fire.

 

They have been around since 1981. or I should say their parent company has.

 

OK, just confirming and good to know. I knew the coil + was simply a trigger for the MSD to pull full battery power.

I set my voltmeter to the highest VDC setting and was only seeing 50V on the coil wires. It may be so quick it doesn't register full voltage though.

I'm going to order the Intellitronix box and see how that goes.