spectra premium distributor failure (roll pin shears off)

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i have had within the past year on two separate 4.9 inline six's (two separate vehicles) the roll pin shear off, causing a no spark situation.

the distributors were both from 'spectra premium' a supplier that you can find on line and at o'reilly autoparts. one was a part number FD11 (for late 70's 4.9's) the other an FD10 for 80's 4.9's with the distributor mounted TFI.

 I, at this point believe it to be a manufacturing error over install error. at first i thought the roll pin was made of *** metal, but upon closer examination i realized that these gears they use are not pressed on but fit with a sloppy tolerance. the motorcraft distributor gears are pressed on, however these spectra premium distributors, the gear slides on and off with no effort w/o the pin in place. this i believe causes the gear to wander on the axis of the roll pin damaging it. in both cases of roll pin failure, the oil pump turns freely with a drill, and the distributor as well. in both cases they also seemed to be getting oil from the block too as the dizzy shaft was oiled.

in both cases of the pin shearing off, the gear fell into the engine (and thankfully hit the oil pan) when i removed the distributor. the first engine this happened on, i removed the oil pan to re-seal and pull the gear out. no signs of excess gear wear, and a junkyard motorcraft distributor in both of em has lasted so far.

the first one, i thought might be a defect, or perhaps some error i made installing it... however i was privy to making sure the pump shaft seats properly and that it's not machined to tall or something like that causing a bottoming out. the first one i installed made it 3 months, and the second one i installed made it 9 months before these failures occurred. it's also important to note neither of the original distributors failed as a result of the gear coming loose. the late 70's one had the pickup wiring rot off of it, and the 80's one i misdiagnosed and put a new one in it. the 80's model FD10 with the distributor mounted module also had a misalignment with the pip's three pin plug and the module causing the module's pins to sit beside the female pins instead of inside them. i don't believe this to have been an issue as they still made contact, but it's just another thing noted that makes me believe crappy engineering as it was assembled that way.

i figured i'd drop a line here about it and see if other's had a similar problem. on other sites i have read similar issues with mallory aftermarket distributors as well, although never personally dealt with one of those. i might add, the job was also difficult to diagnose on the 2nd one as the gear grabbed back on to what was left of the pin and turned the first time, leading me down the wrong path for a bit, till i tried to set the engine to tdc and then realized it was not spinning the 2nd time i looked at it. the oreilly guys thought i was crazy as they had never heard of such a thing. haha. they acted like i was taking money outta their pockets when i said i wasn't about to find out 3 times if this was a manufacturing defect. anyways. just thought i'd drop a line about this. cheers ya all. if anyone has experience with these problems or has one from this supplier still runnin strong, i'd like to know. 

 
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