Here is a nice PDF file (No Video just easy to read words from Holley). It was printed in 2007 and was updated in 2014.
I mentioned above about Accelerator Pump Shooters and mentioned a few sizes. "Shooters come in different sizes. .026", .028", .030", .031" etc."
The PDF says that Pump Nozzle Sizes are available from .025" to .052". I was not aware of the .052" pump shooter.
"Please note that whenever a .040" or larger accelerator pump nozzle is installed the “hollow” pump screw should also be used."
I personally put in the Hollow Screw at around a .035" shooter or if I am using a 50cc pump on the Primary side of the carb.
Cliff Ruggles and others saw an improvement in their carb tuning efforts by adding that system.
50cc pump and hardware on Primary side of carb, 30cc pump and hardware on secondary side of pump.
I have actually had a person stand close to me when working on a carb and the person say "Hey Dude, you installed the carb backwards."
The Mod works well with Auto Trans cars and a tighter converters.
The Holley PDF say: When changing the pump nozzle it’s best to jump three sizes. For example, if there is currently an off - line hesitation with 28 (.028”) pump nozzle, try a #31 (.031") pump nozzle. Some of the "Rules of Thumb" work pretty well at times. Cam tuning for the Pumps help too.
Holley sells a little Pump Cam Assortment Kit
https://www.holley.com/products/fuel...ts/parts/20-12
9 parts, but the reason why I mention this link is because the Pump Cams are identified: Lightest to Heaviest (pump shot) (Light means a small pump shot into the carb)
"Accelerator pump shot relative to cam color from lightest to heaviest are as follows: Black, Pink, White, Red, Green, Orange, Blue, Brown, Yellow" You do not typically see that info in most magazine articles but it is there if you read a lot of the Holley Info on the web.
The Pink Cam seems to work well in most applications and as you can see you have a lot more choices AFTER that cam.
(That is a Kit worth buying and keeping in your Holley Tuning Parts kit.)
So we have touched on Accelerator Pump adjustment, Cams for the pumps, Shooter Sizes and types, Hollow Screws, and a few other things.
I have a couple more before we stop today.
We have a Accelerator Pump Check Diaphragm installed in the fuel bowl floor of the carb on newer carbs. It is typically orange.
There are also older Holley carbs that had a ball trapped in a retainer that sealed when the pump was activated, otherwise it was open and let fuel into the pump cavity. The Orange Accelerator Pump Check Diaphragm is a better deal.
Remove the old diaphragm, stick the long rubber tip thru the center hole, pull it thru the hole until the retainer "bump" traps it in place and then carefully cut the excess material off the part so that the cut is close to the "retainer bump".
If you do not do this the float will have very little travel and the bowl will have little fuel in it and a hesitation will occur. CUT THE STEM OFF.
Tom V.