Alright I have been working on the car this past week. I bought a new msd ready to run distributor and it showed up so I installed it, couldn’t get it to run. We tried all night in every possible position to get it to run and it wouldn’t.
Finally we gave up and put my buddies old mallory boat distributor in it again and she fired right up.
We then thought maybe my spark plug wires are bad, they are the only thing left from the last distributor. So today new pre made wires arrived, installed the MSD diz and new wires. Still not running. just before I pulled the dizz out I started the car with the Mallory marine distributor. Fired right up and idled.
So I have now tried a Pertronix billet distributor that worked for a while and now a brand new MSD that I haven’t been able to get running and the only thing that seems to run is an old corroded marine Mallory.
Any ideas as to why I can’t get my MSD to run the car?
key turned to the run position I am getting 11.98 volts to the coil
Ok I just went back to messing with the car and I started it by jumping the starter relay and using my push button remote with the key in the run position. The car continued to run even after I turned the key off, luckily I had a easy ground to remove.
are you sure that you are getting full 12v in the run position? if you have a ballast resistor or a resistance wire, the hotter the wire gets the less voltage it is putting out. Did you use the relay with the Pertronix? I had to use one as at first the car ran fine but after warming up would not idle. Have you checked to see if there is any spark w/ the msd? voltage out of the tower or at the end of the wire w/ the msd?
I was able to jump the coil straight from the battery last night and start the car with the key. It wouldn’t turn off with the key but disconnecting the battery turns it off. While it was running I tested the original wire going into the coil and was getting less then 12 volts.
I did not use a relay with the pertronix, which I now think is what ruined it, still strange it worked for about 500 miles, I am thinking the reason the Mallory works is because it doesn’t need the full 12v that the msd wants.
When a engine won’t stop with the key off there must be another connection or path for 12V to get to the ignition. An ignition switch with dried up dielectric grease with metal fillings can cause a path. Or the wire (I) from the solenoid that provides true 12V on start is connected to 12V all the time (bad solenoid). Is your Pertronix 12V power wire still connected in.
Can you put a regular points distributor in for troubleshooting?
There’s a variable missing in all of this, I’m just not sure what it is. I agree w/ Claw It in that you should try an old points dizzy, and then go from there.
You DEFINITELY need the relay w/ the pertronix distributors, at least w/ the ignitor 2 &3 internals. I would be willing to bet that given time the Mallory would do the same thing. I would try a relay kit for a full 12v if the MSD requires it as the run lead that feeds the points distributor does not, or should not be getting 12v in the run position, and if you are getting 12v in the run position then something is rotten in Denmark. My Pertronix went at least 1,000 miles before it gave me a problem, but as soon as it did, I installed the relay and have yet to have any issues with it.
Here is what you need to know: voltage divided by resistance equals current in amps. The stock ignition has two resistors in series: the resistance wire and the coil. They are each about 1.5 ohms or higher. You add resistances in series together so you get 3 ohms. Twelve volts divided by three owns gives you 4 amps of current draw through the circuit. The key switch is designed to handle a bit more, maybe 6 or 7 amps max. If you bypass the resistance wire you drop the total resistance to 1 1/2 ohms. Twelve volts divided by 1.5 equals 8 amps of current. This is too high for the key switch and it will get hot and then ultimately fail.
The stock coil had an internal resistance of about 1.5 ohm and was designed to run on about 6 volts. The resistance wire is what reduces the voltage. If you get rid of the resistance wire the coil now sees 12 volts and it will overheat and eventually fail.
When you measure the voltage at the coil, if the points are open, or the Ignitor is open, then you are going to read the voltage across the meter. You will always read the highest voltage across the greatest resistance, and in this case it is the meter itself. If the points are closed or the Ignitor is conducting to ground, then you will read the correct voltage. The best way to do this is to measure with the engine running.
All of this is Ohm’s Law, not an opinion. If you want things to work reliably you have to do it correctly. There are no extra parts that you can just ignore or leave out without some consequence.
Use a relay if you are going to run a low resistance coil. Run a separate power wire from a 12 volt source (hot during start and run) to power the Pertronix or any other electronic ignition that say s it needs 12 volts. A relay can also serve this function. If you don’t know what all this means get a Pedaptor from Rocketman’s Cougar Innovations, wire it as instructed and you can’t go wrong.
So I got a relay that is rated for 12 volts, 30amps. I wired it directly from the battery with an inline fuse between the battery and relay. Then connected the switch power from the I post off the starter solenoid, grounded it to the battery and ran the power out wire to my msd coil. Which has the + and - wires to the distributor along with 1 ground wire from the distributor.
Will this work for a permanent solution?
I also looked at wiring in a msd 6al as an option. After reading the instructions, it appears that it would offer the same function. What other real benefits are there to running the msd box?
The car seems to start and idle well now, just need to dial in the timing. There is some hesitation in it around 50 mph
Thanks guys for the advice and explanations, great stuff.
The nice thing about having the separate box is that you can carry a spare box instead of a spare dizzy should it fail. Not fun in either case. You also will have an adjustable rev limiter that you don’t have to take the cap off of to adjust like I do w/ my pertronix, & multiple sparks (which my Pertonix has). I guess the big question is, do you want everything contained in your distributor, or do you like the idea of a separate box to trigger everything? There are pros and cons to both. I used to carry a spare duraspark box in my high school ride as it always seemed to fail (also fan belt, fuel pump, and a solenoid and voltage regulator in the glove box). All it takes is to get left on the side of the road in the middle of nowhere to make me a little paranoid about not having a few “plan b’s” in my ride.
So many options, I think at some point when I save up I might try the MSD 6al. It would be nice to have a easy rev limiter, although probably unnecessary. it makes me feel safer. That way I would have the separate box but if it went bad I could always run it without the box with the relay easily.
I am collecting a few good spare parts for the trunk.
A regular MSD distributor can not replace a points style distributor. It is a reluctor pickup and it does not conduct current like a points distributor.
You need an ignition box to go along with an MSD. Pertronix, Crane, and Mallory all make points-style electronic distributors.
I got the MSD ready to run distributor so no box needed. I might add an ignition box later on but right now it is working fine without one and using a relay to ensure it is getting the 12v needed.
I’m using the Pertronix all in one and like it, I just keep a spare unit in the car just in case. Have you tuned the Advance curve yet? Trust me, there’s more to be found in that distributor. I picked up quite a bit up top with a spring change.