Why do I have high fuel pressure...

[patrickt]

Steve, how much does your carb tilt in one direction or another? Almost none of our carbs sit perfectly horizontal on an FE, but if you step back and look at yours, how much difference is there between the nose and the tail?

[steve meltzer]

i'll have to check that when i get a chance, probably in a few days. thanx again s

[patrickt]

OK, I was helping another Holley 4160 owner recover from a dicey rebuild and lo and behold the Power Valve that came in the rebuild kit was opening and closing in the metering block almost like the diaphragm in a fuel pump. His vacuum, because of a larger cam, was a little lower than one might think, and the new PV opened at a number that was higher than it should, and that's where the two lines on the graph crossed -- making it open and close in rapid succession causing all sorts of goofy problems. Now, we didn't see the Ajax "white tornado" that we grew up with, but almost... with the engine hot and fuel percolating in to the venturis and "smoking" out. But, changing the PV, and setting the floats a little lower, solved all the problems. And the poor hot idle complaints that he had been enduring were fixed by setting the idle via the secondaries (by the secondary stop screw that you can get to with the proper tool, usually at least) and having the primary butterflies way down low below the transfer slot. I don't know if you ever had a problem with your idle being rich after the engine gets good and hot but, if you do, that's how you fix it. It's literally a magic trick for the 4160 and, if nobody ever tells you about it, you'd likely never guess it on your own.

[steve meltzer]

Thanx for the most interesting education. I didn't know that you could even set the idle at the secondaries, so thanx again for that. The Cobra is still sleeping while I finish some other stuff, tho' never far from my mind.

Did have the occasion, last weekend, to put a kit in my '67 'Vette's 4160. Hard to start when hot and died when hot at idle and had fuel stains on the intake. Had come corrosion around the negative terminal of the battery, which didn't help. With the floats set by the preliminary method (level with bowl inverted) fuel poured out of the sight plug. To get "just a minimal trickle" the N/S had to be screwed in all the way...no threads showing. Car now runs great. Too much fuel is a bad thing...if it's at the wrong time! thanx again. s

[patrickt]

Originally Posted by steve meltzer

Thanx for the most interesting education. I didn't know that you could even set the idle at the secondaries, so thanx again for that.

Holley has a little vid on it -- but you don't hear it discussed all that much. Here: https://www.youtube.com/watch?v=b8ROjrGAH2I In the vid they say you can only access the screw with the carb off the engine, but it is my experience that, with most of our manifolds, you can use a right angle, short end straight blade screwdriver and make the adjustment on the car. With a non-removable Turkey Pan, it might be touch and go on that. For a large displacement, decent duration camshaft, engine like most of the FEs that are in our Cobras, idling the 4160 off the secondaries is the single best trick I know, next to cleaning the air bleeds, to make the engine idle and run beautifully at low throttle.

[steve meltzer]

i'll check it out. thanx again. s

[steve meltzer]

I realized (while working on the 4160 from my '67 'Vette) that while you can raise the float level, and thus the fuel level, on the 4160 by turning the needle/seat CCW, the opposite isn't true...before you can drop the float, you must rock the car to empty the bowl with the sight plug out or else the float won't drop because there's too much fuel in the bowl. Then you can turn the N/S CW and thus decrease the fuel level. Duh! steve