CRG Discussion Forum
Camaro Research Group Discussion => Mild Modifications => Topic started by: MRPENNYPKR on July 09, 2010, 02:56:07 AM
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I have restored my 69 SS350 4sp to pure stock original condition except for deleting the AIR pump and associated plumbing. (cam, pistons, heads quadrajet are factory) Are any changes necessary to the base timing, carb settings, fule mixture and other tuning settings?
Thanks,
Tony
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Are any changes necessary to the base timing, carb settings, fule mixture and other tuning settings?
Thanks,
Tony
A.I.R.-equipped cars had leaner primary jetting, and much more conservative/retarded base timing and distributor advance curves, with the vacuum advance connected to a "ported" source in order to make the vacuum advance inoperative at idle. This increased exhaust gas temperature to make the A.I.R. system "afterburn" in the exhaust manifolds more effective under idle and low-speed traffic conditions.
In your case, the factory base timing setting was 0*, and full centrifugal advance (30*) wasn't reached until 4700 rpm.
You can restore a lot of performance by using 8*-10* as your base timing setting and re-curving the distributor to bring the centrifugal advance all-in by 2800-3000 rpm, and by connecting the vacuum advance to a full manifold vacuum source so it's fully-deployed at idle. You may want to limit the centrifugal advance to 26* or so, to keep your total timing (initial + centrifugal, measured with the vacuum advance disconnected and plugged) no more than 36*. Hardly any money involved in doing this, but you'll really feel the improvement.
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Thank you John.
Tony