Why do I have high fuel pressure...

[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:

[steve meltzer]

Point well taken, and, I was in a hurry. I'll pull the carb off the car (the nth time) and then I can get a great look, etc. Got some work (tho' generally fun, challenging and interesting) in front of me. Always something with these old cars. s

[steve meltzer]

OK, took the carb off the car and here are a few of the things I found:

1) the cam is def'n a red part #240 which, as was pointed out, is probably wrong for my carb. (no damn wonder my sox never match!)

2) I have some orange ones and a cream colored one. need to check the numbers.

3) The gasket at the bottom of the accelerator pump mechanism was torn.

4) As seen in these photos, the gasket that I have that interfaces between the carb body and the metering block was missing two orifices, so i just poked a hole in the gasket. As you can see, it's not very good. I just fixed this with a real punch, and it looks fine now (not in the photos). Not sure of it's importance in the circuitry.

[patrickt]

Originally Posted by steve meltzer

As seen in these photos, the gasket that I have that interfaces between the carb body and the metering block was missing two orifices, so i just poked a hole in the gasket. As you can see, it's not very good. I just fixed this with a real punch, and it looks fine now (not in the photos). Not sure of it's importance in the circuitry.

Uhhhh, no. That hole is always there on the main body, but it's only used when you have an auxiliary idle air bleed, which you don't. I don't think punching a hole in your gasket will make a difference one way or the other though, but test it out by putting a small straw in the hole and see if you can't blow through it. IOW, I think that's a dead end hole that does nothing. Try using the orange cam and use hole #1.