Why do I have high fuel pressure...

[patrickt]

I would first check the accelerator pump. You have a 30cc pump in your 4160, which should be squirting a volume of 3cc on each good full stroke of the pump. So, run your car for a minute or so to get the front bowl nicely filled, then shut the engine off. Tuck a sandwich baggie (or some other suitable receptacle) around the squirter, get back in the car, and with the engine OFF give the accelerator pedal five nice, hard pumps to the floor. Pull the baggie of gas back out, trying not to spill it, and pour it in to your graduated cylinder. If you don't have 15cc's of gas in there then repeat the test. If you consistently fail this test, then you've found the problem and we'll figure out what's broken on that circuit.

[patrickt]

... and if you have the orange cam in there, which is what I think you probably have, since it came stock, then anything under 12cc or so is going to raise a flag. Different cams, and screw hole 1 or 2, will give us different results, but we'll just check your output with one of the Holley charts and see if you're at least in the ball park for volume. But if you've got a different color cam in there, let us know.... I'd really just like to see it come back abysmally low.

EDIT - Here's a handy chart that tells you what volume you can expect from the different cams and positions.

[steve meltzer]

It's technically tough to catch all of the effluent in the experiment, but I tried hard, 3X. Biggest volume I could capture on 5 pumps was about 6cc...so, about 1.5 cc/ pump. The cam is maroon/brown and in position #1. thanx. s

[patrickt]

Originally Posted by steve meltzer

It's technically tough to catch all of the effluent in the experiment, but I tried hard, 3X. Biggest volume I could capture on 5 pumps was about 6cc...so, about 1.5 cc/ pump. The cam is maroon/brown and in position #1. thanx. s

The maroon/brown cam is a big cam. http://documents.holley.com/pumpcamgraph.pdf I think there's something wrong on the accelerator pump circuit. Shooting from the hip, it's going to be one of these:
1) The linkage is screwed up and the cam lever is not getting pushed down right to actuate the pump;
2) The little orange umbrella seal is leaking, so you're not getting a good squirt in the right direction, or the diaphragm is worn out, or the spring is broken or missing (elves do that);
3) There's a clog in the passageways from the pump to the nozzle;
4) The nozzle area is mucked up preventing a good squirt. You know there are two gaskets and that little plumb bob thingy that go under the nozzle. If you remove the nozzle and take it away to clean it, elves always sneak in your garage and hit the throttle, making the little plumb bob fly out and disappear. Are you absolutely positive it's still in there?

[steve meltzer]

Originally Posted by patrickt

The maroon/brown cam is a big cam. http://documents.holley.com/pumpcamgraph.pdf I think there's something wrong on the accelerator pump circuit. Shooting from the hip, it's going to be one of these:
1) The linkage is screwed up and the cam lever is not getting pushed down right to actuate the pump;

I think this all will be easier to diagnose with the carb off the car. Agree?

2) The little orange umbrella seal is leaking, so you're not getting a good squirt in the right direction, or the diaphragm is worn out, or the spring is broken or missing (elves do that);

With the carb off the car, i might as well replace the diaphragm. How do you tell if the orange umbrella is sealing the vent? is it supposed to be flush with it?

3) There's a clog in the passageways from the pump to the nozzle;

That's in the metering block, right? Soak in carb cleaner or ??

4) The nozzle area is mucked up preventing a good squirt. You know there are two gaskets and that little plumb bob thingy that go under the nozzle. If you remove the nozzle and take it away to clean it, elves always sneak in your garage and hit the throttle, making the little plumb bob fly out and disappear. Are you absolutely positive it's still in there?

I call those "Jesus" gaskets/washers, 'cause you'll always say, "Jesus" where are those %$*&^&*&^ things! (no disrespect meant!)

thanx. steve

[Gaz64]

Steve,

Are you sure the pump cam is brown, and not a discoloured white, orange, red etc?

The brown and yellow cams are meant for Dominator 4500 carbs, which have a larger throttle shaft.

Gary

[patrickt]

The brown cam is the Tyrus of Holley Accelerator Pump Cams. Here's a pic: