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you are seeing the needle opening and closing. You will also never "push" fuel through the jets, thats not how a carburetor works. The bowls are not pressurized, they are filled to a level set by the float.

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Yep, thats why I said "to" the jets instead of through the jets. I was just referring to the pumps ability to keep the bowl full all the time. Well you and DT seem to be viewing it as I have been, not a big deal. Thanks for your thoughts guys. Any others care to weigh in? I am FAR from being an expert on this stuff and I know there are a bunch of savy guys here.

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Doesn't sound like anything to worry about to me. I think it's flickering because the pump is sufficient for the job. The seat opens, the pressure drops, it closes and it spikes back up. Dead head regs do that. I've got a Magnafuel 500 with 12 to 10 to 4 -6 lines and it flickers around too, even with air bleeders back to the tank, and it does it idling or at wot, just faster at wot. If it were steady and dropping I'd worry about that, because it'll only be steady while the seats are open or completely shut. Oil filled gauges or isolated gauges look steady because of the snubbing effect they have. A dry gauge close to the carb, or on the reg reads totally different than the others.

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with DT and TS

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I run a Mallory 140 pump fed by 10AN line from the cell to the pump, then 8AN all the way forward to the reg, then dual 6AN lines, one to each bowl and the press gage is reading press to the rear bowl, just off the reg.

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I run a Mallory 140 pump fed by 10AN line from the cell to the pump, then 8AN all the way forward to the reg, then dual 6AN lines, one to each bowl and the press gage is reading press to the rear bowl, just off the reg.

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While we're discussing it, does anyone here see a problem with the way I've got it plumbed? (above and attach) Pic is just to show where I'm picking up the press reading. The line goes to a cowl mounted gage.

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I see no problem with what you have...mines almost a carbon copy and keeps fuel pressure rock stable and fuel delivery is no problem..

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In my opinion,pressure is not nearly as important as volume.It would not matter if the pressure dropped to 1 p.s.i.,so long as the bowls stay full.The reason the pressure is set where we do is to overcome the restrictions to get the fuel into the bowl.

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Very true on the volume. The reason we use 7.5 or
so(based on the gauge accuracy)is because if you go
much higher it will blow the needle off of the seat.
Also the thing with pressure is... its a by-product
of resriction, the greater the restriction the greater
the pressure untill you reach the max of the supply
pressure. So that 7.5 psi is what the needle and seat
are holding

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In my opinion,pressure is not nearly as important as volume.It would not matter if the pressure dropped to 1 p.s.i.,so long as the bowls stay full.The reason the pressure is set where we do is to overcome the restrictions to get the fuel into the bowl.

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Someone made a comment recently(in the last year, if I remember correctly) that they wanted the fuel pressure set at or under 5.5 to 6.5 lbs to reduce the possibility of aerating the fuel from the tank to the carbs I had my fuel pressure set at the regulator with the engine running at a idle at 9.5 lbs, I reduced it to 6.5 lbs and didn't see any noticeable change at the track or on the street My car is not real fast (10:34 best ET in the 1/4 mile) so my results may not carry any weight, your results may vary I did find out later using a O2 wide ban that the car didn't have a good enough fuel system to allow me to fatten up the carbs big enough to slow the car down until I switch pumps from a Magnafuel 275 to a Magnafuel 300 pump,whch did slow the car down with no other changes made to the car except the pump switch My message is if you can slow the car down in 1/4 MPH by fattening the mixture up enough until it slows down your fuel delivery system is probally okay, no matter what the fuel pressure gauges reads during the run, if you can't fatten it up enough to slow the cars MPH down you probally have a fuel delivery problem. I did not say fuel pressure problem Air in the line can compress showing pressure when it is not all fuel in the line flowing

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