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MSD distributor shaft broke
#1107293
11/04/11 09:06 PM
11/04/11 09:06 PM
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Joined: Jun 2006
Posts: 344
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noplanb
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OP
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The shaft on my MSD 8387 distributor broke today. Nice clean snap.
The oil pump and cam didn't seize, the intermediate shaft gear isn't galled, the timing chain didn't break. The @*&! thing just snapped.
The shaft tang fits all the way into the slot on the intermediate, but it does wobble slightly. Would this, combined with Offshore Quality Materials, account for the break? Just wondering if I should be looking at a new intermediate as well as the distributor shaft. The shaft was from Mancini, and looks fine.
FWIW, the engine's a 493, oil pump's a Melling M63HV. Everything turns freely and the oil pump makes pressure with a priming shaft.
remember when you said honey, some day that car is gonna look so good in front of our house
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Re: MSD distributor shaft broke
[Re: RapidRobert]
#1107296
11/04/11 09:24 PM
11/04/11 09:24 PM
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noplanb
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By wobble I mean that the tang fits all the way into the shaft but doesn't securely bottom out, it wiggles slightly back and forth in the slot.
I tried the intermediate shaft on an old Mopar dizzy, it fit about the same.
I wasn't running the car hard, just slowing down for a stop sign when it bucked and died.
remember when you said honey, some day that car is gonna look so good in front of our house
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Re: MSD distributor shaft broke
[Re: noplanb]
#1107298
11/04/11 09:37 PM
11/04/11 09:37 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Quote:
it wiggles slightly back and forth in the slot.
Rotational slop. I'd bet on defective shaft as all dizzys have that slop from excessive play as the tang is not as wide as the intergear slot and never seen one fracture. The cure is to appropriately pound each side of the dist tang end to expand it and or adding the 1/2" ID collar (McMaster/Carr & others) with the set screw onto the end of the shaft (snug then mock it up to set the exact distance on the shaft) then carefully pull it up/out & tighten the set screw fully then put it back in & this is done to stop spark scatter (timing jumping around) rather than preventing stressing a shaft so I'd say a new shaft will take care of it whether you eliminate the slop or not EDIT when you go together with the new dist shaft add some 1/2" ID flat washers above the collar with the roll pin till the axial play in the dist shaft to dist housing itself is .005"
Last edited by RapidRobert; 11/04/11 09:53 PM.
live every 24 hour block of time like it's your last day on earth
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Re: MSD distributor shaft broke
[Re: RapidRobert]
#1107299
11/05/11 11:56 AM
11/05/11 11:56 AM
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Joined: Jun 2006
Posts: 344
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Thanks Robert.  I'm going to talk with MSD tech support Monday about the axial free play, but I'm also going to check the overall length of the shaft compared to the Mopar dizzy. Have to accept the materials situation, but I don't want to just replace the shaft and hope for the best. I was lucky with the circumstances of where it broke this time, don't want to press my luck.
remember when you said honey, some day that car is gonna look so good in front of our house
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