Hi,

Went to move the RR today and it barely started. Now it will not fire at all.

I am 99% sure it is ignition related. What is a good way to troubleshoot whether it is the pickup or the MSD? Car cranks great, MSD is wired straight to the battery both power and ground, same as it has always been. Engine spins over great, has fuel. Get an occasional pop at best now. MSD is a 6AL, distributor is a Mopar Performance unit that has had the advance modified but nothing else.

I will do the pull plug test with plug grounded see if has a spark.

Best regards, Dave

Most likely the MSD box. Look up their testing procedure on their website.
MSD= might suddenly die!

Yeah pull the plug at the dist and jump it... if it
sparks then its the pick up.. if it has advance in the
dist you can pop the cap and turn the rotor also to
see if it sparks then(after you pull the plug and jump
it) and see if the reluctor gap is good(.008)
EDIT
If you turn the rotor.. make sure the coil lead is
near the ground

Thanks guys,

I will go to the MSD site and check out the testing procedures. Mr P Body, how do I trigger it to eliminate the pickup as the problem? The distributor still has advance in it so I can move the rotor. Actually, light just dawned on marblehead, I think. The idea is to move one of the reductor points past the pickup, then see if the coil wire triggers a spark. If it does not trigger the spark, how does that isolate the the pickup as opposed to the MSD? I apologize if I seem dense, spent all of today recovering from the work computer total failure, just barely saved the hard drive, so brain firing on even less cylinders than the RR.

Michelle, my incredibly smart and understanding wife, really liked the new acronym for MSD.

Step 1: Use your digital multimeter (or whatever) to check for resistance across the pickup wires going into the distributor. Hopefully you have a reading over 200 ohms. If it's open your pickup is faulty and needs to be replaced.

Step 2: While you have the distributor unplugged pull the coil wire at the distributor and place it near a ground that is not a fuel line, etc. What you are about to do will emit a strong spark from the coil wire! Strip the white wire coming from the MSD box (points trigger) and touch it to a ground to trigger the MSD. A strong spark should come out of the coil wire. No spark means either a bad coil or bad MSD. Check coil for resistance, oil, etc. If you still have not found your problem...

Step 3: Pull the distributor cap. Make sure the rotor turns when the engine is turning over. Line up the fin on the reluctor to the pickup and make sure you have around .008 air gap.

Let us know what the results are.

Hi Jeremiah,

I will do that pickup test. DO you really mean I want to see a reading over 200 ohms, not under, for the pickup wires? I have a multimeter so that is no problem. To be absolutely clear, unplug the two wires coming from the distributor to the MSD. Then check across the terminals of the wire coming fr0m the distributor with the multimeter set to ohms. Does it matter where the reductor is? I would think not in this scenario as there is no current to create a magnetic field.

I think the airgap is correct and the rotor does move, at least it moved over time.

I don't know, it sounds like using a fuel line as a ground could give the most interesting results.......

Seriously, using the white wire, I assume have the ignition key on, then touch the white wire to ground while the big wire from the coil is about a 1/2 inch from ground should produce a big ass spark when the white wire is removed from ground, essentially doing what the points do.

Will most likely get to this tomorrow afternoon as already 2100 here so all this advice is incredibly helpful as I can go in with a full list of tests to use.

Best regards, Dave

Make sure the ground wire from the msd box is still connected to a good ground source and hasn't been compromised. Damhik!

Thanks for all the replies. I did the following diagnostics this morning:

1) put an ohmeter across the connector from the pickup, reading around 350 ohms.

2) I then took the wire off the cap and stuck a screwdriver up in it and laid it across the engine. I kept the wire from the distributor disconnected. I took the white wire and touched it to ground, then disconnected. Could hear the spark and seemed to be nice and blue.

3) Then, I did the same test only using a jumper across the connector from the MSD to the distributor. Similar result, consistent spark.

4) I then hooked the distributor back up. Left the coil wire set up as before. There was enough slack in the advance to move the reductor past the pickup. Nothing, or very occasionally a spark. I then loosened up the distributor and rotated the body back and forth. Similar result.

5) I did not check the gap but it looked about right. Not sure where the brass feeler gauge is currently located, entropy seems to have occurred on the bench.......

I am leaning toward the pickup but if anyone has some thoughts that will be great.

Best regards, Dave

Oh, next question. IT is a MP distributor. Does anyone know the Rock Auto number for the pickup or should I just use a later model than 1970. I know I found one before but that was a while ago.

Okay, I just looked up a 75 RR with a 400 and it shows a Standard ignition products part number LX102 or an Airtex number 4P1340

Will either of those work?

Best regards, Dave

Replace pickup

Thanks MR. P Body,

Do those part numbers look to be the correct ones?

Thanks for the clarification, I will get on it.

Did you try switching the polarity of the pickup wires?

Was suggested to me here by Bob George when I had a similar MSD no start problem. It worked! He said he sees it all the time. It's actually mentioned briefly in the MSD instructions - if the polarity is incorrect, it could cause the box to advance or retard the timing 40 degrees.

Worth a shot.

I just went through this. Turns out my pickup was OK, but there was corrosion in the connector.

LX102T is made in China, it's Standard's economy brand. So pop the extra $ for the LX102. Although I have to say no problems with the LX102T I installed, just not sure of durability.

R.

I would confirm the air gap.

I installed a 6AL and a new MP dist in my buddies 383 and it ran and then it ran poorly and then it refused to fire at all. Brand new dist and the gap was too wide. Not a lot too wide but too wide none the less.

Tightened it up and Vrooom!

Kevin

Wow, thanks for the continuing input. I will go with the LX102, I figured it was something like that based upon the description and warranty length. Shipping cost is exactly the same for the cheaper part as the better one.

I will positively confirm the air gap before ordering a new pickup.

I believe the polarity is correct. When I installed the MSD several years ago I went through the procedure but will double check, as stated, costs nothing to do.

I think corrosion in the connector is not the problem as I have unplugged it and plugged it back in and that should have helped.

Ok, last bits. Checked the gap with the brass feeler gauge. The .008 feeler gauge slides on through with slight drag. The .010 definitely a tight fit so I think good there.

The orange wire on the pickup is connected to the purple wire on the MSD box which according to the instructions is correct.

Will order parts and install.

Thanks again for all the help.

Best, Dave