MSD 6AL missing
 

I am running an MSD 6AL ignition with an MSD billet distributor and have problems with misses at higher rpm.
With the strobe I can clearly see the mark starting to jump between 38º and 30º advance at above 3000 rpm. The timing is set to 20º advance at idle and 38º maximum. I am running Webers so the initial advance is correct so.
I did have a problem in the beginning which I improved replacing the cable going from the MSD box to the distributor with a shielded cable, which is probably not twisted inside. The cable runs well away from the plug cables and the shield is grounded.
The distributor is ok and it has a new vented cap but that has not brought improvements.
Has anybody experienced a similar problem and found a solution?

Hi Stefan,

one item to check is rotor phasing.

MSD has a good tech sheet on the subject.http://www.msdignition.gr/download/tb_rotor_phasing.pdf

There are a couple things to check
 

Eljaro To start with there have been many problems with the cap and rotors on the MSD setup. The carbon pile in the centers are breaking or burning out. The center contacts are falling out of the cap. There is no spring tension on this contact from the distributor cap. Carbon tracks are happening inside the cap and causing miss firess. What spark plug wires are you running? Check all the ends and make sure they are tighen on the contacts. Also add a little grease, sillicone to help with heat transfer. You didn't say how old the coil is? this could also be another problem that it is breakin down under high rpms. Where is your coil mounted and which one is it? Is it mounted vertical or horizontal? Mounting a coil on a motor is not a good thing either. The vibrations and heat the motor gives off, shorten the life of a coil. To start with, drill a large hole in the top of the distrib cap in both sides of the #1 terminal. As said before, you need to faze the distrubutor to the motor first and then setup the timing. I carry a whole setup in my car for MSD ignitions. 6AL box, HVC coil, Cap and rotor and electronic internal parts. You said you have a miss, recheck the cap and rotor or install a new one. Some of the guys here are using a stock cap from GM I think and it works better than the MSD stuff. Do a search for this problem. Faze the motor and then start to replace parts. If the coil is on the motor or horizontal this would be the first thing to check. MSD system beats the crap out of coils and distrubutor caps and rotors from the long, high outputs of spark. It's like welding. The car will run fine with the holy cap on it. You may also see the problem too.%/:MECOOL: Rick L.

Bingo!
That was it. The MSD cable color coding is wrong in my case and thus the timing was out of phase.
I used an old distributor cap, drilled a large hole behind the #1 plug cable connector and watched the rotor with the timing light. The rotor tip was firing at the tail end instead of the lead. I did switch the cables, adjusted the distributor and all is well now. I connected everything as per MSD's instructions, but that apparently is no guarantee that everything will work 100% if they m,ess up with the cables and the phasing.
I wonder how many have the same problem and do not know. I have been driving around with a wrong phased distributor and only now have I discovered it.
Timing is steady now. Will try out the car tomorrow.
Thanks for the tip.

I tried out the car today. Some improvement there but there still is that hesitation. It is subtle and not easy to notice because there is so much power.
Driving at a steady speed with the engine revolving above 3000 rpm there seem to be some cylinders missing. I do not know if the MSD 6AL box is defective, and if it is how to check that (maybe with an oscilloscope) or if it is the magnetic pickup. The basic measurements with the ohmmeter check out ok.
I changed all the plugs, I use a new distributor cap (the one with the venting holes), the plug cables are new super conductor from MSD and the coil is new also.
So my problem is still unresolved

Are you 100% sure it's not a carburetion problem?

Stefan,

Make sure the gap between the 8-bladed reluctor inside the distributor is no more than .025 inches away from the magnetic pickup. Believe it or not, those two stainless hex screws let the pickup move around bit when tightening them up. Don't forget the silicone adhesive to lock it down. And put a little light oil on all the iron parts to keep them from rusting up so quickly.

You can do it with the dist in the engine, but it's easier with it out. Let us know if that is an issue.

Tom

The gap between rotor and pickup is 0.025.
From what I have read in the MSD Troubleshooting forum the distributor pickup either works or doesn't. So I do not know if replacement will be the solution. Same goes for the 6AL box according to MSD tech support. Or maybe not.
Something somewhere is wrong.The car basically runs fine except for that continuous hesitation which sound like misses. It gets worse as the engine gets hotter.When fully accelerating there are no such misses to be noticed. Only when driving at a steady speed at around 3000-4000 rpm.
What else is there to check?

My MSD 6AL2 just crapped out. was pinging and hunting and jumping about. car died -- removed out of loop---, -- all ok now.

not sure what happened.

Panavia,

It seems that some of the MSD units have a habit of doing that. I believe that I saw where someone on here carries an extra one with him just in case.

Ron

Eljaro,

Have you tried running the 2 wire cable from the dist. outside the body to try and isolate these cables from others.

If everything is new and is doing the same thing you might have some sort of interference

Just a thought

Eljaro ... Priobe has a good idea on the distributor wire routing . On mine ( ERA #757 ) , ERA makes a point of telling you to separate the distributor wiring from all others . I ran mine across the back of the engine and then down the driver`s side valve cover and intake and all other wires down the passenger side . I was told that you could get some ignition problems due to induced transients .

No way to get this fixed!
 

Still the same problem : up to 3500 rpm when the distribitor reaches maximum advance no problem, from there on the the timing mark starts jumping around between 30 to 40 degrees. Timing is set to 18º initial and 38º max.
I replaced the 6AL box with a new one :mad:and still the same problem. I had the cable going from the box to the magnetic pickup in the distributor routed behind the firewall and along the left fender. The wire is also shielded and both shield ends are grounded.
I do not know if it can be the pickup, but I have read that these units either work or don't. Before ordering a new pickup I would like to know if that has caused problems for someone else. I do not know what else can cause this:(.
Thanks for your help.

Eljaro,

Are you looking at the timing mark to see your problem or are you feeling the problem?

I dont think you will get a misfire from your timing missing. You will feel a surge with the timing moving from 30 to 40.

There might not be anything wrong is you are just looking at the timing mark. MSD 6 al play alot of tricks with timing lights.

I thought I had a problem when I saw my timing move backwards when reving the motor to 3000 rpm, it was the timing light with the MSD module playing tricks

Also, for giggles try this take a piece of wire and replace it with your springs ( basically lock out the dist). Advance the timing to 32 degrees and see what happens. Check and see if your timing is still moving which it should not.

The pickup has nothing to do with the advancement of the timing. check your springs

Your thoughts

only one end of the shielded cable should be grounded.

Thank you for the tech link. Is there one also for the "reluctor gap" issue? "Bending the tung" too?

I simple test
 

Eljaro Could you check 2 things for me, First just remove the cap on the distributor. Get a socket and ratchet on the crank bolt and rotate the crank shaft back and forward until the distributor rotor starts to move in both directions. How far did it ( crank) move?? 1/4" 1/2" 1"?? Timing chain could be a problem. The other thing is to pull the distributor and check the gear on the distributor for wear? The other thing I was thinking about is the end play on the camshaft. If there is too much, the timing will be all over the place with the motor running. Some motors have oiling systems that push the camshaft forward with high pressure and the cam sides back with steady or low pressure. Mark the distributor before you check the gear. IMO I don't think that the wiring going into the MSD distributor will make a differents. The car ran both ways. I am also wondering if the wiring is broken internally or 1 of the connections is in poor shape. You can Ohm test the wires to death, as long as 1 or 2 strands of wire are connected you will get a good reading from end to end. A better test is to run 12 volts though the 2 wires to a Bulb like a headlight that will draw a light amp load but give you a good test of the wires. Rick L.

No play on gear whatsoever. But the gap between distributor rotator tip and cap bronze terminal is quite large, something like 1/16". Isn't this too much?.
The misses are noticeable as slight and repeated breaking actions on the engine when driving at constant speed at over 3000 rpm. I will test locking the advance mechanism and see what happens.

Are you still running the Webers?
 

Eljaro Are you stilling running the webers with this problem? How do we know it's not a carb issue? The timing change could be a loss of power? Is it possible that you are having a dirt issue in one of the carbs on the main circuit? Did we look at all the plugs? Color and gap? Sorry, we get so crazy going after electricial things we over look the basics first. There is no backfiring when the timing changes either through the carbs or the pipes? Did you check the timing chain play with a larger breaker bar for play? How many miles on the motor? Rick L.

Im running a MSD6AL my cobra got where it did not want to crank. Pulled cap the tip that runs on the rotor was burnt back inside cap. Got a new 1 still would not crank, my friend tested the pickup, said he thought it was bad, replaced it, she cranked an ran fine.