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Old 07-06-2009, 07:38 AM
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MSD Reluctor / Mag. Pickup issue.

So, I've been having some hard starting problems. Sometimes it would fire, and sometimes it wouldn't. Timing was just fine, but starting it up was like trying to move a mountain. Motor is a 10.8:1 383 SBC with a 258/263 @ .05" solid roller cam, so there isn't a whole lot of cranking compression.

This past weekend was the last straw. I locked out my timing to see what it would do, and it was an absolute dog (which should be quite the opposite considering it needs so much initial). I set it at 36 degrees locked out and went for a test spin. It wanted to die, but I think it's due to the carburetor tune/vacuum leak that I found prior. That's fine. I pulled over to grab some food, finished, and went outside to start, and it would not start, no matter what I did. I advanced timing, then retarded it to see if it had any effect at all on spark. Nothing.

I finally got down and dirty and started looking at parts and doing some debugging. I did the MSD coil wire jump test to the firewall, and I know for a fact I have spark from the coil. It had to be in the distributor. I was recently in a wreck where the car was totaled, but the engine was salvageable. The advance weights on the distributor were bent a tiny bit, but it wasn't anything that was major (or so I thought). I took out the distributor yesterday and gave it a once-over, and noticed the reluctor paddle to magnetic pickup clearance was varying as I turned the distributor gear. It was wobbly!

I know this would cause hard starting issues, but I never noticed it once it would fire. Before I had the timing locked out, it would fire, but it would take 10 or so seconds of cranking to light up. It just stopped starting all of a sudden after I locked the timing out. There was plenty of voltage, but after cranking for a while, it obviously lost 1-2 volts or so. Once I hooked up my truck, and used jumper cables, it would start (with the wobbly shaft/reluctor paddles), but only if I was getting around 13 or so volts. Even then it would take 5 or so seconds to crank up, and starting was hit or miss. Once it lit up though, it sounded fine and idled well.

I know the reluctor paddle clearance would cause hard to start issues (which is why I already have a new distributor on the way), but would it cause some power (HP/torque) loss? Does the magnetic pickup serve any other purpose other than a trigger signal in relation to the spark sent from the coil? Does it control the 'intensity' of the spark sent from the coil in relation to the clearance of reluctor/magnetic pickup?

Thanks.

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Old 07-06-2009, 08:32 AM
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The air gap should be .015 according to MSD techs. This air gap changes the intensity of the spark. I recently had a new MSD distributor for a 5.0HO Mustang, the air gap was close to .050. It would drop spark in random cylinders at idle. The spark from the coil was somewhat weak mostly, with some short outbursts of a strong spark.
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Old 07-06-2009, 08:37 AM
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Quote:
Originally Posted by carsavvycook
The air gap should be .015 according to MSD techs. This air gap changes the intensity of the spark. I recently had a new MSD distributor for a 5.0HO Mustang, the air gap was close to .050. It would drop spark in random cylinders at idle. The spark from the coil was somewhat weak mostly, with some short outbursts of a strong spark.
If that is true, then no wonder it felt a bit down on power. I don't think I was dropping cylinders at idle though as idle was just fine. Maybe it was masked by the fact I have a big cam. Thanks.
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Old 07-06-2009, 08:48 AM
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At first I suspected the coil was bad, but further testing pointed to the coil 'trigger' from the pickup being weak.
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Old 07-06-2009, 12:31 PM
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Reluctor

Mr. Cook - the MSD reluctor looks exactly like the same Ford part from an old "Duraspark" distributor - could they be interchanged?

A guy buying a whole new dizzy for the sake of a reluctor seems like a hard way to go!!
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Old 07-06-2009, 12:40 PM
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Yes they can, I have done it.

The only problem I can see with his, is that something is bent. Not knowing if it is the housing, or the shaft, makes me think a new distributor is warrented.

I doubt the pickup/reluctor got bent in the wreck.
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Old 07-06-2009, 12:44 PM
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I agree

I agree - a part that runs out like crazy is not to be trusted.

But the bit of knowledge about parts interchange is useful....Thanks
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Old 07-06-2009, 02:45 PM
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The magnetic pickup itself was nicked in the wreck, but it was still functioning fine. The problem is the shaft that the reluctor paddles are on is bent, and that shaft does not have a replacement part, nor am I under warranty anymore. It was a slight wobble that I didn't pickup on when looking at the dizzy the first time.
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Old 07-06-2009, 03:05 PM
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Upper rotor shaft

Can you get the "upper rotor shaft" - I don't know what MSD calls it - off the dizzy and take it to a machinist?

I "fix" old Ford distributors by fitting them with later model reluctors and pickups - by simply getting the upper rotor shafts remachined for a reluctor (cut off the point cam).

Once you have the upper rotor shaft of the MSD in your hands - and a new reluctor from NAPA ($6.00) - a guy used to repairing things may be able to help you out.

If the lower shaft is bent.....that is a different animal....
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