[carbking]

Back to the original posters question:

Drilling out the discharge holes will NOT give a larger pump shot, simply a quicker shot with less duration, with the possible result of a delayed hesitation.

The pump shot may be increased by increasing the pump cylinder volume. Increasing the pump cylinder volume may be accomplished by:

(1) Changing the height of the pump cylinder by: (A) using a shorter pump or (B) shortening the effective length of the pump rod or (C) changing the radius of the relation of the pump rod to the intermediate pump arm.

(2) Changing the diameter of the pump cylinder (more difficult than A above) by boring the pump well oversize, and fitting a custom made oversize pump.

Reiterating, the pump cylinder volume determines the pump shot volume; whereas the discharges nozzle orifices determine the length of time for the pump shot to be delivered.

As to the feed versus slot discussion: sometimes engineers are asked to resign a product so that the product will still work although less reliably at a lower initial cost. In the manufacture of a carburetor bowl, much less expensive to cast in a slot rather than machine a seat, a hole, and a cross passage after the casting step.

Jon.

[Tom Vaught]

Originally Posted by carbking

Back to the original posters question:

As to the feed versus slot discussion: sometimes engineers are asked to resign a product so that the product will still work although less reliably at a lower initial cost. In the manufacture of a carburetor bowl, much less expensive to cast in a slot rather than machine a seat, a hole, and a cross passage after the casting step. Jon.

Thank You Jon.

Tom Vaught

[bayside_norm]

Hope I'm asking this in the right place and not hijacking a thread. 66 gto tripower with no fuel pumped at the rear carb. I cleaned the carb guts, installed new pump, now its sending fuel to the nozzle nicely (on the bench, anyhow). But the bore is not filling from the bottom. It's been soaking in gumout for days, no luck. Any thoughts?

[mgarblik]

There is an inlet check system in the bottom of the pump well. I have seen the proper aluminum ball get stuck and not allow the well to fill. Also, I have seen the steel, (larger ball) incorrectly be installed in the inlet check in the bottom of the well and jam-up the circuit. If that has happened, the ball can be very hard to remove. I have seen extreme situations where a Chevy floating cup pump has to be used when the inlet check system is no longer usable due to a wrong or stuck inlet check ball. This is the area you need to look at. Good luck.

[bayside_norm]

I was afraid of that! Going to try once more to free it by drilling a tiny hole in the passage from the outside, and poke around with a wire. I will fill the drill hole with JB if it works. (Painting the carbs with Eastwood zinc chromate anyhow). This isn't a hard-core restoration but I'd like not to put 'those other guys' parts in there if I can make it work the way it's supposed to.

Thanks for the fast reply!