Lotus Elan

Distributor

PostPost by: JACKJABBA » Fri Nov 28, 2003 10:09 am

I have my distributor off at the moment, and have noticed that there is some verticle play of the shaft. I have read an article which said to check the amount of play, but no indication of how much is acceptable was given.Does anyone know what is the max play, or is it that if there is play then the distributor should be changed?

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PostPost by: type26owner » Fri Nov 28, 2003 11:56 pm

.002" or less but not bound up is perfect.
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PostPost by: Dave50/1 » Sat Nov 29, 2003 12:32 am

I have been experiencing sporatic detonation, sometimes during acceleration, but not always. Occasionally I'll hear some detonation under a steady throttle. Seems to be more like scatter; the wires, cap and rotor have been replaced, and I'm useing a Pertronix Ignitor in place of points. I have measured my end play on the distributor about .017". Any chance these two issues are related?

Thanks for any input.
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PostPost by: type26owner » Sat Nov 29, 2003 3:47 am

.017" will give you about 10 degrees of scatter. Power time the dizzy for the most advance possible for the fuel you're using. I test mine by loading the engine at low rpm and retarding the dizzy until it just doesn't cause it to knock.
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PostPost by: JACKJABBA » Sat Nov 29, 2003 12:17 pm

Can the distributor be rebuilt to remove the play, or will it need a replacement?

Anyone have any links for distributor rebuilding?

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PostPost by: BillGavin » Sat Nov 29, 2003 1:12 pm

End play by itself shouldn't affect the timing, as it just changes the part of the cam where the points rubbing block sits. End play can be adjusted with the thrust washer fitted between the drive gear and the bottom of the distributor body. Unless someone lost the thrust washer, I wouldn't expect excessive end float without other wear as well.

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PostPost by: type26owner » Sat Nov 29, 2003 3:55 pm

There's a nylon thrust bearing under the plate for the mechanical advance which wears out slowly and causes the play. I suspect it's purpose is to dampen the mechanical shock loading contributed by the points from damaging the drivegears since in the direction the dizzy is rotating, the pitch direction of the helical drivegear is contineously pulling the mainshaft down against the nylon thrust bearing. It is also designed to be compliant somewhat by virtue that the washer is relieved (chamferred) on the back to clear the rolled connection of the mainshaft and the advance plate and therefore has some additional springiness or cushioning.

Since the rotating parts of the dizzy have inertia and can likely be excited to resonant and with the engine constantly changing rpm the excessive play most certainly degrades the ignition performance. If you have this problem then fix it first before doing any other tuning. If left loose for a long time you should carefully inspect the drivegear teeth on the dizzy and the jackshaft for damage.

Simply insert a shim between the drivegear and the housing to take the play out and that should fix your scatter problem. Stop using points is also a good move.
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PostPost by: pereirac » Thu Jan 01, 2004 4:29 pm

I think, if you convert the distributor over from a points system to an optical (Lumenition) or magnetic non contact system that will help as movement in the spindle should not affect the timing as much as relying on the cam to open and close the points.

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