Quote:
Originally Posted by azfordman
The carb only has idle adjustment screws on the primary side. Secondary throttle plate is closed 100% at idle. Took the primary screws in all the way, backed each one out 1/2 turn and hooked up a vacuum gauge. Increased the idle screws until I achieved maximum vacuum, then backed each one in a hair to drop it 1 hg of vacuum....kinda tough because the vacuum is not steady....the needled bounces and fluctuates around 1-2 hg, but is strong around 21 hg. The car idles fine...just a bit of a lope to it. There does not seem to be any miss at idle....only when cruising with minimum throttle, if I down shift and kick the RMP's up the stumble/miss goes away.
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What kind of carb is it? You may be into the transition circuit on the primary side, which will cause a stumble when you're in between the idle circuit and the jets.
As for timing, you need to choose a little more "scientific" way of waiting until it pings then backing it off.
I'd set the initial anywhere from 12-16 degrees and check the curve at full advance. 34-36 degrees total should be fine. Check to see where the total advance comes in. Lighter cars will stand a quicker timing curve. I like my Cobra engines to hit total advance around 2200-2400 rpm.