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Old 11-04-2012, 02:24 PM
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The power valve will not operate correctly until it is boost referenced.
its and easy mod..
Untill that is done,, remove and block of both power valves and use rich +6 to +10 jets in the primary side
for WOT dyno testing under boost. You need to read with two vacuum gauges @WOT under full boost.
one on the carb base one on the intake manifold. They will read different.

need both upper and lower vac gauge readings at WOT Max boost max rpm on the dyno.
(this tells you how hard the blower is pulling on the wide open carbs , at WOT under boost)


make sure the vac secondaries are opening correctly on the dyno. (paper clip test on the sec diaphram linkage) These can be pesky.... leaks.

Once you ave boost referenced the power valves correctly,, I predict a 10.5" power valve will be right for your motor..... Untill that is done,,, block the power valves and jet up.

Need to know the best dyno test power jetting pri (with blocked power valves) and sec.
Then need to know the PVCR's orrifice sizes in your primary metering blocks (measure it)
(remove power valve and look)

Again, the power valves will not work right until boost referenced , with 14PSI boost.
remember start dyno tuning with rich carb jetting and conservative spark timing under boost on pump gas.
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mustang 671 (11-04-2012)