Why do I have high fuel pressure...

[patrickt]

Originally Posted by steve meltzer

So here are 2 photos of the bowl, its float ... which looks low to me,

I can find nothing wrong in any of the pictures. That picture of your bowl also looks fine (because there's no gas in the float bowl to make it rise). To reassure you, here's a picture of mine, which is properly calibrated, although you can not tell it from the picture.



The only way I know to test a Power Valve is with a vacuum pump and something like the Moroso tester. But you can push the plunger back and forth with your thumb and finger and try and feel something different from the old one. I think I would just put the old one back in for now -- we're pretty confident it was working alright and if the new one is "stuck" in the open position, that could contribute to an overly rich mixture. An open Power Valve generally boosts up the circuit by a good ten jet sizes, which is quite a lot.

[steve meltzer]

Right, but mine also looked low when held upside down, as the factory says to set it dry. More later. s

[patrickt]

Originally Posted by steve meltzer

Right, but mine also looked low when held upside down, as the factory says to set it dry. More later. s

Alright. There is an old trick that you can use if you really think something is misbehaving between the float mechanism and the N/S valve, but it only does it when you have the bowl screwed on. The only reason I know this factoid is because of the configuration of the secondary side of the 4160. You probably wondered to yourself "why is the float in the secondary side black nitrophyl and the float on the primary side brass?" The reason is not that Holley wanted to cut corners; it is, instead, because a brass float will interfere, sometimes, on the metering plate on the secondary side of the 4160. You can't tell this, of course, when the bowl is off the carb, because there is no interference and everything works perfectly. The way you can check a float in that situation, is with dental floss. You tie the floss around the float and fish it out of one of the top bowl screw holes. You then put the bowl back on with three screws and you can test the operation of the float by pulling the floss. You can also blow in to the fuel line and, if your lungs are strong, you can muster a good 2.5psi to see that the N/S is indeed closing. As I said, this is a rarely used trick, but you now have it in your back pocket just in case you need it.

[steve meltzer]

Originally Posted by patrickt

Alright. There is an old trick that you can use if you really think something is misbehaving between the float mechanism and the N/S valve, but it only does it when you have the bowl screwed on. The only reason I know this factoid is because of the configuration of the secondary side of the 4160. You probably wondered to yourself "why is the float in the secondary side black nitrophyl and the float on the primary side brass?" The reason is not that Holley wanted to cut corners; it is, instead, because a brass float will interfere, sometimes, on the metering plate on the secondary side of the 4160. You can't tell this, of course, when the bowl is off the carb, because there is no interference and everything works perfectly. The way you can check a float in that situation, is with dental floss. You tie the floss around the float and fish it out of one of the top bowl screw holes. You then put the bowl back on with three screws and you can test the operation of the float by pulling the floss. You can also blow in to the fuel line and, if your lungs are strong, you can muster a good 2.5psi to see that the N/S is indeed closing. As I said, this is a rarely used trick, but you now have it in your back pocket just in case you need it.

Actually, I did find it odd that the primary was brass, the secondary, black nitrophyl, thanx for answering that question. So, if the brass is on the primary only, then there would be no need to do the floss test, right? (Can't interfere with the secondary metering plate if it's only the primary side.) Also, if I did the floss test, should I use the wax or unwaxed kind? (only joking!) s

[patrickt]

Originally Posted by steve meltzer

Actually, I did find it odd that the primary was brass, the secondary, black nitrophyl, thanx for answering that question. So, if the brass is on the primary only, then there would be no need to do the floss test, right? (Can't interfere with the secondary metering plate if it's only the primary side.) Also, if I did the floss test, should I use the wax or unwaxed kind? (only joking!) s

Right, I don't think you need to floss either side of the carb. With the primary bowl back on, and the sight plug out, and the electric fuel pump on, if the gas is not pouring out the hole like a river, and you can see the gas level using a little flashlight, then I think all is well with the float and needle/seat. In other words, that's good enough for now and should be good enough to get the car running. The only thing I can come up with that would let you have a "tornado" of gas through the primary is a power valve that was stuck in the open position, so that gas was just pouring by it in gobs. Watching for the accelerator pump arm, and making sure it's not positioned improperly under the pump, is the only other object that's even involved with the bowl -- and I can't think how that would cause the tornado effect, it would just make your squirter not squirt.

[steve meltzer]

I assume that the little black triangular piece is afixed correctly at the top of the bowl, under the gasket, right? s

[patrickt]

Originally Posted by steve meltzer

I assume that the little black triangular piece is afixed correctly at the top of the bowl, under the gasket, right? s

Correct.