Re: WIDE OPEN VACUUM TEST......................
[Re: Thumperdart]
#1595254
03/19/14 12:06 PM
03/19/14 12:06 PM
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Joined: Jan 2003
Posts: 10,082 Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,082
Frostbitefalls MN (Rocky&Bullw...
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At 7,000 rpm and 100 percent VE, you pull 950 cfm with 470 cubes. Your VE may be over that, but not by much. I would think the pv would be plenty high, and your WOT vacuum will be 1.6 or less. Probably the only real test would be a AFR test to see what is going on. You could also put a new 4.5 in it and test it.
Last edited by gregsdart; 03/19/14 12:16 PM.
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Re: WIDE OPEN VACUUM TEST......................
[Re: Thumperdart]
#1595258
03/19/14 01:59 PM
03/19/14 01:59 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Quote:
How many of you folks have done a dyno or street wide open test to see how much vacuum you have? After much thinking and research I`m thinking my 3.5 p/v COULD be closing at wot if I`m pullin more that a few inches of vacuum............Anyone?
if your pulling over 3.5" of vacuum at WOT you've got issues. 3.5" would indicate a very big restriction on the intake/carb. i'd look for fuel delivery problems.
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Re: WIDE OPEN VACUUM TEST......................
[Re: Thumperdart]
#1595260
03/19/14 02:53 PM
03/19/14 02:53 PM
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Joined: Nov 2004
Posts: 2,495 Oregon City, OR
Baxter61
top fuel
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top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
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Quote:
I tried that years ago before the wide band and just may again it`s just a pain testing on the street at 120+ mph............
need a co-pilot?
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Re: WIDE OPEN VACUUM TEST......................
[Re: Aspen7695]
#1595263
03/23/14 10:48 PM
03/23/14 10:48 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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I never use a PV lower than 6.5 except in the borrowed carb i used for drag week last year and i believe that was happening to me but it was actually helping.
There is no reason to have a 3.5 PV in a carb. Do not listen to anyone that tells you to use a PV that is 2" lower. That is complete nonsense
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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