fuel pressure fluctuation - Team Camaro Tech
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post #1 of 3 (permalink) Old Mar 11th, 03, 06:46 PM Thread Starter
Join Date: Feb 2003
Posts: 24

I have a small block in a 68 and am using a holley blue electric pump with a return back to the tank.I have been attempting to adjust the fuel pressure to the carb.Take it in mind I am using a liquid filled guage installed on the fuel feed line on the carb.and it seems the pressure fluctuates alot.I cant figure out what is going on.Also I was told that when setting the fuel pressure,that you must set it when it is flowing.Is having a return line plumbed in good enough to set the pressure with key on engine off,or must I get a jug to catch the fuel while setting?Thanks for any help with this problem.
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post #2 of 3 (permalink) Old Mar 12th, 03, 09:39 AM
Join Date: Oct 2002
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Some liquid guages do not have a dampner in them and no matter what, the pressure will fluctuate.

Holley recommends a dampned guage for a stable pressure measurement.
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post #3 of 3 (permalink) Old Mar 13th, 03, 01:07 AM
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Join Date: Dec 2000
Location: Kentwood, MI
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Defiinately set your pressure with the engine running. You can rev the motor a little from the carb and watch if pressure steadies out, the fluctuation on the gauge could be from the needle and seat in the carb opening and closing.

Another way to test is to install a piece of plastic tubing between your fuel press gauge and the fuel inlet tube. Then tape the gauge to your windshield where you can see it and make a few full throttle runs to see where the fuel pressure goes at WOT. Set it for 6 - 7 psi at WOT and you should be set.

E85 racer and E85 carb builder

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68 Camaro, E85 powered 427" small block. 9.96 @ 133 MPH, 1.319 sixty foot on motor. 5.92 eighth @ 116 with a 1.42 sixty breaking beams with back tire on the bottle
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