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Old 09-03-2010, 08:19 AM
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Originally Posted by rajsid
Does anyone know the factory recommended idle RPM for a 502 HO motor is?

I was told that the initial timing should be 14 degrees. I am trying to find out at what RPM should I get 14 degrees at.
If you are using a mechanical advance distributor, just be sure that the rpm is low enough that the mech. adv. is not adding any advance. Disconnect and plug the vacuum advance like Brian said and you will be fine.

If for some reason you find that there's advance coming in even at a low idle, you will need to add a heavier advance spring to prevent this.

The Ramjet 502 is:

Ignition timing: 8 BTDC @ 800 rpm; 36 total @ 5000 rpm.

You can compare your cam, etc. to it to see if the 800 rpm should also apply- but I would say it should be a good rpm to use.

FWIW, the 502 HO uses (what is shown in this particular spec chart):

36 total @ 3600 rpm, with vacuum advance disconnected.

The HT 502 uses:

Ignition timing: 4 BTDC
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