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MSD disaster

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Stingray72

Guest
Well, just when I got everything in perfect working order with the new MSD ignition system, it broke.

I was going down the highway for the first time since I got the tach working with the new MSD distributor (8572). Everything was working great when, all of a sudden, the car shuddered, the tach went to zero, and the engine sounded like it was way, way out of time. I pulled over and the distributor housing had spun a good 20 degrees clockwise. I did a good job of tightening the distributor clamp, so it took all of my strength to rotate the distributor back close to where it was supposed to be. Fast forward a few hours and I was back home taking the distributor out. Here's what I found:

I removed the tach drive and found that it had seized. I could not move it with my hands at all. The gear on the distributor that drives the tach was free-spinning on the distributor shaft. It appears that the pin that holds that gear on the distributor shaft had sheared off, and this is the only reason that the distributor was still functioning enough to get me home. None of the gear teeth that I could see were missing or significantly chipped, although they were worn a good bit considering I only had 100 miles on the distributor. My theory is that a shaving from one of the gears somehow locked up the tach drive and the subsequent bind is what caused the whole thing to turn 20 degrees.

I just sent the distributor back today. Has anyone else had this problem? Are there any causes that I might be unaware of? Thanks.
 

Rowdy1

Well-known member
Joined
Mar 26, 2001
Messages
1,180
Location
Lake Hopatcong, NJ
Corvette
1962 CORVETTE-SOLD 2004 Z16 Z06 CE
WOW.....

I'm sorry to hear about your mishap. I too bought the tach drive MSD and the new cable but after building the engine, at the last minute decided to go with an electric tach. I haven't heard of anyone having your problem and I do see a few of them at the local cruise nights. If I should hear anything, I'll let you know. Let us know how you make out. Are they just going to send you a new one or diagnose this one?
 
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Stingray72

Guest
Thanks.

I requested that they send me a new one, but I'm sure they do some kind of inspection. I talked to an MSD tech before I sent it back. He seemed kinda surprised. The distributor was otherwise such an impressively-made part that I'm willing to believe that this was a rare mishap. My tachometer appears to be unhurt, and I doubt that the force of the bind was enough to mess up the timing chain. The car sure ran great with this system. If anyone else has had any experiences with this kind of problem, please let me know. Thanks again.
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
Stingray72:
So sorry! Coupla-3 thoughts on cause(s): possible manufacturing problem/ possible factory assembly problem/ possible user assembly problem ... I know you don't wanna hear that last one ... but wasn't TD disassembled-TD reversed-disassembled-returned to fact config?

Did you inspect the distributor's main drive gear that engages camshaft ... and how is the gear on cam (I'd be more concerned about the cam than T-chain)? BOTH must be in GREAT shape ... if not, you'll have more problems later.

You can probably rest easy ... MSD usually makes things right.
JACK:gap
 
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Stingray72

Guest
Jack, believe me, I was trying to think of any way that I could have messed it up because I DON'T want to think that it was a manufacturing defect. I suppose I could have chipped a gear when I reversed the drive, but it went together so easily that I doubt that was the case. Plus, I never even fired the engine with the tach drive reversed.

Both the gear on the distributor shaft and the gear in the tach drive showed signs of wear, although the gear in the tach drive was a little more worn that the one in the distributor shaft. This alarmed me, because I only had 100 miles on the distributor. In comparison, the main distributor drive gear (at the bottom of the distributor) showed no signs of wear at all. Of course, I could only see a few of the teeth on the tach drive gear because it was seized. For all I know, a tooth could have broken off on the other side and caused it to seize.

It should arrive at Summit tomorrow or the day after, and assuming they approve it for exchange, I should have a new distributor early next week and we'll see how it goes. It appears that this is not a common problem, so my hopes are high.

Thanks.
 
R

resto75

Guest
My son bought a MSD ign for his truck and it didn't even work out of the box. So much for MSD it went back and the original was hooked back up.
 

silver 80

Well-known member
Joined
Jul 9, 2001
Messages
562
Location
madison,wi
Corvette
1980 silver with blk interior 1987 blue / blue
doesn't the tach drive gear have to shimmed to the proper depth?
tom
 
G

gdh

Guest
Have any of you used Pertronics or the Crane ignition system?
 
S

Stingray72

Guest
Silver, there is no shimming for the MSD tach drive, but there IS a gear lash adjustment. However, this was supposed to have been set at the factory. Since the gears were worn so much, perhaps the lash on mine wasn't set correctly.

Jack, Summit is apparently sending me a new distributor, but it's on backorder now, of course. Judge Murphy is paying me a visit on this ordeal now, too. I won't have a new one until the end of the month.
 
H

Hijinx

Guest
I'm using the Pentronix unit. It has worked fine from day one, and I was not sure that I had it set up correctly. I could never get it to the feeler spec's they noted. However, it has worked fine. Now, since I am planning to switch over to TPI, there is a question of whether or not I can continue to use it. I plan to call MSD and Painless Wiring to see if something can be set up for me to use an MSD 6AL and my original distributor w/Ignitor to drive the TPI computer. I'll let you know what I find.
 

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