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Discussion Starter #1
Car seems to run alot better w/out it. I like the rough idle too. Should I use it or how do I adjust it. When hooked up it starts to break up if held at any RPM. What dangers are there if not used? Will it foul plugs because of the idle? Thanks very much. Richard

Sorry, carb w/ duraspark Dizzy

[ July 04, 2005, 08:20 PM: Message edited by: rbordner ]
 

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What type of distributor? I have a Mallory Unilite vacuum advance distributor on mine without the advance hooked up. Was told by the tech at Mallory that basically it advances the timing about 10 degrees at the idle. He also said that it wouldn't hurt it to leave it unhooked. My distributor has a mechanical advance of 24 degrees by itself...

Scott
 

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Discussion Starter #3
TTT
 

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If it's misfiring at any rpm with the vvacume advance connected, then you need to take a closer look at your timing. Recheck base and mechanical advance.

Vacume advance is supposed to give you a little extra timing at part throttle cruise when vacume is at it's highest. Gives a little better fuel mileage. You can't run that much timing under a load, or detonation will beat the pistons to death.

If the idle is higher with the vacume connected, then it's working correctly. If the idle drops, maybe the vacume diaphragme is torn.
 

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Discussion Starter #5
Bob, I have a rookie question. How do I check mechanical timing.

And the detonation you mentioned, wouldn't I hear it pinging. I just want to make sure that I am not slowly killing hte motor. Richard

Hope everyone had a great 4th
 

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You check the mechanical advance with a timing light. A dial back light is nice, but not required. You take a look at base timing at idle, then gradually add rpm's and watch the timing marks. If you run out of marks (common with stock dampers) use a ruler and a paint pen to make more.

The Cobra is pretty loud, especially when you get on it. That's usually when detonation occurs. So if it's a small amount, you may not hear it, or be able to discern it from background noise.
 

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Discussion Starter #7
Thanks Bob, It sounds like running the vac. adv. will decrease the chance of detonation? If that is right I would prefer to use it.

What should the mechanical advance be? And is that when the pointer stops moving as it is revved? Thanks for the help. Richard
 

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Vacume advance will *increase* the risk of detonation by adding more timing than you can safely use.

On a stock distributer, the mechanical and vacume advance are set in stone, and somewhat limited. The specs seem to vary a little year to year; and I expect CA smog motors are a little more limited.

Factory specs call for 10* initial/base timing. Many people add another 2-4* of base in order to obtain 2-4* more mechanical and vacume advance. So start at 10*, and see where you get.

If the engine is lean or rich, it will run poorly, so make sure that is operating correctly.
 

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Discussion Starter #9
No more comments on the vacuum adv? Richard
 
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