Quote:
Originally Posted by Jeff_Keryk
........ More advance at idle ........
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Easily done with a curve that is properly matched to the application. If additional (vacuum) advance is needed, the curve is not right.
Quote:
Originally Posted by Jeff_Keryk
........ Ported timing came in with the smoggers which wanted to raise operating temps ........
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Not true. See my previous post:
Quote:
Originally Posted by 88 coupe
........ The factory used the ported (above the throttle valve) source to help compensate for the delay while the fuel, from the (accelerator) pump shot, traveled to the combustion chamber ........
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Beginning with their first use of vacuum advance systems, in 1936.
Manifold vacuum was only used, as one leg of the TVS (thermal vacuum switch) circuit, to control overheating in emission controlled engines.
Norm