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Persistent problem with my MSD distributor
I do not understand.:(
This is the third time in less than 7000 miles I replaced my MSD distributor. As you can see below the coal in the center of the head is dead. Everything else is brand new (spark plugs, coil, ignition box ...) Any idea ? [IMG]http://img13.imageshack.us/img13/2091/rotorb.jpg[/IMG] |
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Can you buy just the center bit ? Soul. |
That center part was made of cheap carbon and burns out quickly with the high voltages. I finally went to a Mallory distributor and have never regretted it. I did hear some person had found a MSD cap and rotor with stronger centers and that it had lasted a long time. But I can't verify that as I never saw it.
I thought about trying to drill that part of mine out and find a plug from another distributor that would fit it and glue it in there and see if it would work, but decided I liked the Mallory electronic one best anyway. Ron |
Another thing is that frequently the rotor center pickup doesn't reach high enough to contact the rotor button in the cap. If this is the case then any time the coil fires there is an arc to the rotor from that button. Think about that happening any time the ignition fires and you can see that it wouldn't take long for the button to erode. Some guys have just bent the rotor pickup a little up to make contact and have had success. Others like Ron (and me) have ****e canned the whole thing.
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me too, i am now on my last cap......the next cap i need will necessitate going to a duraspark distributor, with a recurve, it will be plug and play into the MSD box.
Fred |
You replaced the cap, not the distributor. Still, that is not right to have to replace it so many times. Is this the one you are using?
MSD Ignition 8433 - MSD Extra Duty Distributor Caps - Overview - SummitRacing.com |
This is not to unique to your car. The are are several of us here in Houston all of whom run FE engines with the MSD 8594 and we have to carry spare caps because this happen every 3-5k miles. I switched to the cheaper black Borg-Warner GM cap, part #157.
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This is a somewhat common problem with both MSD and Mallory. No need to replace the whole distributer, just the cap.
The MSD often uses their version of an early 70's SBC cap. Take your MSD cap down to your favorite parts store and match it up. You can paint it red if it makes you feel better. |
Lovehamr has the solution. The tang on the rotor must have firm contact the carbon post located in the cap. PERIOD If you bend the rotor tang toward the cap with firm contact you will not have any problem. I use Wells or Blue Streak caps and rotors because they are much cheaper and you can get the copper not aluminum terminals. MSD red is very identifiable but these other guys offer old school black distributor caps, good for an extra 5 MPH at least! or like he said .... "Others like Ron (and me) have ****e canned the whole thing." works too !! LMAO:LOL::LOL::3DSMILE:
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Not exactly, it is this one : MSD Ignition 84335 - MSD Distributor Cap and Rotor Kits - Overview - SummitRacing.com |
The easy solution is as mentioned above, chose which one works. For me I bent the tang and put a small smear of dielectric grease on the tang; assemble the cap on the distributor, secure it, then remove it and look for grease transfer onto the center button indicating good physical contact. If there is an air gap (as mentioned) arcing and thus over heating will occur, causing degradation of the carbon button. It can happen to ANY distributor. Keep in mind, the center wire and button carry 8 times the number of sparks that any individual cylinder does. If you are using resistor plugs, resistor wires and a large coil there is a huge load placed on the seconday part of the ignition system.
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How about taking an old cap and cutting a side window into it to see how high the center contractor actually reaches? could be the wrong rotor for the cap?
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I bent the tab up a little, years ago. :) Still running the same cap!:cool:
David |
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David |
Amazing to me. First thing I tried was bending cap up to contact. Didn't matter.
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A tell-tail sign that the center carbon on the cap is self-destructing in weird readings on the tach. Bending the center contact up too much is also a problem that leads to cap destruction.
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I had the same problem with my MSD cap. I bent the rotor tab up too. That helped until I took the cap off the next time to see if the carbon button was still there. It was until I took the cap off at which point the carbon button fell into the distributor. I switched to the Summit brand cap and rotor and I haven't had the problem since. Summit Racing SUM-G5234 - Summit Racing® Distributor Cap and Rotor Kits - Overview - SummitRacing.com
Chris |
This can also be aggravated by large plug gaps, questionable plug wires and generally anything causing high secondary ignition system resistance.
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