boiling fuel

[undy]

Originally Posted by Power Surge

I thought maybe you had a brain fart .

The tubes are strictly vents. You can't have pressure equalization between them because the air cleaner is obviously open to atmosphere (otherwise the car wouldn't run). You'd need some kind of sealed enviornment for pressure equalization to occur.

Also, the higher end Holley based carbs with the upgraded needle/seats can handle 8-9 psi.

Not true..

Actually you do have a pressure equalization between the two. The vents are common to the inside of the air cleaner which is under atmospheric pressure or a little less depending on rpm, throttle position and the negative pressure within the air cleaner. That all being said, they will equallize due to both bowls venting to a common area. If there wasn't a vent then under the right conditions the bowls wouldn't fill due to being "air locked".

Remember... Atmosphere (@ sea level) is around 14 PSIA, which is still a pressure

Dave

[Power Surge]

Originally Posted by undy

Not true..

Actually you do have a pressure equalization between the two. The vents are common to the inside of the air cleaner which is under atmospheric pressure or a little less depending on rpm, throttle position and the negative pressure within the air cleaner. That all being said, they will equallize due to both bowls venting to a common area. If there wasn't a vent then under the right conditions the bowls wouldn't fill due to being "air locked".

Remember... Atmosphere (@ sea level) is around 14 PSIA, which is still a pressure

Dave

Well of course you have atmospheric pressure, but that's not going to keep the bowls equalized in the case of different FUEL pressures between the bowls which is where I thought the conversation was stemming from. If you've got 8 psi in one bowl and 5 in the other from some odd fuel log, flow path, or heat related issue, atmospheric pressure is not going to "equalize" the fuel pressure in the bowls.

[wtm442]

Originally Posted by Power Surge

If you've got 8 psi in one bowl and 5 in the other from some odd fuel log, flow path, or heat related issue, atmospheric pressure is not going to "equalize" the fuel pressure in the bowls.

The pressure inside the primary and secondary bowls of a Holley carb are always at the same pressure .... atmospheric pressure (the pressure inside the air cleaner) ... which is approx 14.696 PSIA at sea level or Zero PSIG

Of course, the fuel pressure inside the fuel line just before the needle and seat of the two bowls "could" be different only if there was a tremendous restriction or blockage inside the fuel line(s) leading to the needle & seats.

Originally Posted by Mr Magoo

I wrapped my line from the pump to the carb, added a Holley heat shield with spacer, laid a piece of reflective insulating pad underneath the fuel log and just generally tried to eliminate obvious points of heat transfer. I like the results. The car doesn't get doggy when it's hot like it used to.

I'm seriously considering getting rid of the braided steel lines for fuel entirely and going with rubber and insulation, but no urgency at this point.

No need to get rid of the braided stainless. With the heat insulation, the small amount of heat transfer that would be eliminated would be minimal. If you need further temperature reduction to avoid percolation you need to increase the amount of outside air that flows thru the engine compartment. But that is very difficult to do when the car is stuck in stop and go traffic. Therefore, the next step, if needed would be to add a return line to the gas tank.