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Distributor Help


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My 74 350 sbc was running strong when suddenly it started missing like a couple of plug wires got switched or a plug wire came off. There is a deep clacking noise coming from the stock points type distributor. Inspection of the distributor shows no damaged or loose parts under the cap. All the wires are in place. Adjusting the points has no affect on the missing and clacking noise. Also, the engine keeps dying at idle. :(

 

Any help would be appreciated.

 

Thanks

 

Miles

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Replaced rotor, points, condenser and cap. Dwel is set to factory specs. But when I checked the timing the timing mark is jumping back and forth. I noted that there is some slop in the mechanical advance and a vacume test on the vacume advance shows that it does not move the plate when a vacume is applied. I don't think the vacume advance has ever worked. Up until yesterday the engine ran real strong. Engine runs real rough at idle but revs up ok.

 

Any clues what may be wrong?

 

Thanks

 

Miles

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  • 3 weeks later...
Guest Anonymous

Miles;

 

The deep clacking of the distributo itself has to be fixed! Usually a rollo pin holds the drive gear on the distributor. I have seen these shift/bend berore they shear off completely and the engine screws up. To have such a noise appear suddenly in that area and the engine keep running tho' is somewhat of a mystery; in this case the timing would retard but hardly cause the timing mark to fluctuate.

 

I suspect that the cam has begun to shift back and forth (endplay) because the only way the timing can change like that is either from the distributor area or the cam area (cam drives distributor) and either one or the other or both are changing. Pull the dist. first for inspection. Look closely at the rollo pin. If it looks ok then remove the cap and hold the rotor tight while you crank on the gear back and forth real hard with your other hand. If no movement is seen/felt then forget the dist. But just check for lateral movement of the gear end anyway to see if the bushing there is still good.

 

If nothing is found down there then the cam cover area is where you will end up because it would be the dist drive gear part of the cam moving back and forth, not only making the timing mark flux but also clacking as it's gear keeps having to take up the slack to the dist. gear (Electrically, that slack movement between the gears would be what you are seeing as timing flux).

 

Otherwise, some would say "It's the timing chain"! Perhaps. If you have the cover off there and still haven't fount the trouble then check it out very closely because, even a new chain could be flawed or the timing gear itself be coming loose!

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