Holley Power Valves
04-08-2013, 09:54 AM
#1
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Holley Power Valves
Guys;
With your help, I managed to get the secondaries adjusted properly on my 4150... totally smooth acceleration!
Now, another question... Power valves. The ZZ383 creates about 15" Hg at idle, so I'm thinking that the carb should have 7.5: Power Valves front and back.... Is this correct? Also, are there any symptoms if the Power Valves are not properly matched... i.e. like surging or flat spots??
Thanks!
Joel
With your help, I managed to get the secondaries adjusted properly on my 4150... totally smooth acceleration!
Now, another question... Power valves. The ZZ383 creates about 15" Hg at idle, so I'm thinking that the carb should have 7.5: Power Valves front and back.... Is this correct? Also, are there any symptoms if the Power Valves are not properly matched... i.e. like surging or flat spots??
Thanks!
Joel
04-08-2013, 10:59 AM
#2
Safety Car
What PV to run will depend upon when the boosters can pull the fuel in the main metering system. One that opens too late, say a 3.5, will cause a flat spot on throttle transitions. An example is you're on the main metering (fuel going through the jets and out the boosters) and you give it a little more pedal and acceleration sags a wee bit, then picks up. Keep in mind that the PVs do nothing until there is sufficient signal to pull the fuel through the boosters. One that opens too early may be less noticeable. But the symptom from early enrichment can be the same as not enough and that's a flat spot.
You will not get surging with a PV misapplication. Surging is a steady state condition caused by lean main circuit or a lean idle circuit under very light throttle.
You will not get surging with a PV misapplication. Surging is a steady state condition caused by lean main circuit or a lean idle circuit under very light throttle.
04-08-2013, 11:12 AM
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What PV to run will depend upon when the boosters can pull the fuel in the main metering system. One that opens too late, say a 3.5, will cause a flat spot on throttle transitions. An example is you're on the main metering (fuel going through the jets and out the boosters) and you give it a little more pedal and acceleration sags a wee bit, then picks up. Keep in mind that the PVs do nothing until there is sufficient signal to pull the fuel through the boosters. One that opens too early may be less noticeable. But the symptom from early enrichment can be the same as not enough and that's a flat spot.
You will not get surging with a PV misapplication. Surging is a steady state condition caused by lean main circuit or a lean idle circuit under very light throttle.
You will not get surging with a PV misapplication. Surging is a steady state condition caused by lean main circuit or a lean idle circuit under very light throttle.
Gerry; Makes sense... With a 15" Hg Idle vacuum, should I be looking at 7.5" PVs at least to start, or something even higher than that... say 8.5's ? I'm getting a very slight flat spot during the transition as you described it.
04-09-2013, 08:14 AM
#4
Jtalka, I spoke with Holley Tech Dept on my Carb, I'm pulling 8HG on the guage, he said to cut that number in half and go to the next lower PV, which would be a 3.5, it solved my problem.
04-09-2013, 11:58 AM
#5
Melting Slicks
