Back in 1992, Bob Kunz told me that both primary and secondary metering blocks in my model 4150 Holley LIST 3124 take the "85" power valves (ie. they open when manifold vacuum reaches or falls below 8.5 inches Hg). GM info hard to find, as the Interim Shop Manual ST-71 (spring '65) only mentions the primary jets (#72) and the secondaries (#76).
Well the last few times I started my car, it ran like (censored); poor idle, soot out the exhaust, etc. Some spark plugs were sooty and dry; others wet with smell of gasoline. Turns out the secondary metering block power valve diaphragm was ruptured, and fuel was draining into the intake manifold. That's what I get from driving it (say) 20 miles in the last decade
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Just wondering if others are using "85" power valves on their 3124's. Also, do both PV's have to be the same rating ? What happens if you have [to use extremes] a "25" on the primary and "105" on the secondary block ? Is there a chance that the secondary power valve will open before the secondary barrels (throttle plates) open, as these activate by signal from the boost venturi (?), and not manifold vacuum AFAIK. Or should the primary always be an equal or numerically higher rating than the secondary ?
Well the last few times I started my car, it ran like (censored); poor idle, soot out the exhaust, etc. Some spark plugs were sooty and dry; others wet with smell of gasoline. Turns out the secondary metering block power valve diaphragm was ruptured, and fuel was draining into the intake manifold. That's what I get from driving it (say) 20 miles in the last decade

Just wondering if others are using "85" power valves on their 3124's. Also, do both PV's have to be the same rating ? What happens if you have [to use extremes] a "25" on the primary and "105" on the secondary block ? Is there a chance that the secondary power valve will open before the secondary barrels (throttle plates) open, as these activate by signal from the boost venturi (?), and not manifold vacuum AFAIK. Or should the primary always be an equal or numerically higher rating than the secondary ?
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