Why do I have high fuel pressure...

[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