3310-1 vacuum secondary check ball?

[PRH]

I’ve done the Philips screwdriver thing a few times.
Worked good for me.

[Tuner]

The Philips screwdriver trick is one I used many times decades ago, but a drawback of that is making a calibrated leak with any kind of consistency, some will leak more than others. Using the Phillips screwdriver trick with two carbs on a tunnel ram, one will move quicker than the other. Most of us know if you look close at the check ball seat, most of them have a small groove or notch which is the bypass leak Holley puts in them.

The reason I drill a bypass is for consistency. A .035" hole is usually about right.

[rfoll]

I have over a half dozen of the bodies. If I don't like the results I can change to a different setup. I did find one of the orifice types, curious what application used them. .

[rgalajda]

All of the 3310-1 carbs I have seen have the brass tube in the primary venturi along with dog leg boosters. Also the 3310-2 has the brass tube. 3310-3 deleted this.
GM factory 780 holley’s that I have seen were also like this.
If they are as original they have the plain spring along with a check ball and almost always have the groove next to the check ball. The correct check ball is .1860 diameter.
All of these carbs use #330 diaphragm.

Tuner’s method of drilling a .035” bypass, along with the check ball, is what I prefer. The plain spring will almost always be fine then. I recently restored an original Holley carb for a 1971 Cuda 383 and drilled the .035” bypass. The result was again excellent. I always install the check ball.

Compressing the assembled vacuum pod and timing the release gives you an idea as to where you are.
I always do the blow test to gauge the opening rate when the carb is back together. But you have to be consistent as to where you hold the blow gun over the brass tube with throttle open, of course.

The Quick fuel adjustable vacuum pod also works excellent . I have used this. The baseline setting for the adjustable needle is 1.5 turns off the seat.
Quick Fuel Brawler BR67258 uses this along with the brass tube and dog leg boosters. The vacuum pod has a .065” brass orifice along with a purple spring and adjustable needle screw. I have tried this carb and found that it worked excellent , rated at 770 cfm. A little rich as delivered.

Holley 600cfm List 9834-1, used a vacuum pod with a .040 brass restrictor and no check ball along with a black spring.

[levisnteeshirt]

Taking the check ball out might work in a drag car ,, I've done it ,, might try the drill trick on one for the next one I do

I wanna swap a 850 throttle plate on one and 830 stepped boosters on the next one too

[rfoll]

The carb went down the road Saturday, although I'm sure I haven't seen the last of it. I couldn't make the secondary throttle plat screw move. I soaked it, beat on it, heated it, and several combinations of those. I manufactured a hard steel screwdriver to fit the hole and it broke off. As an alternative I bent the tab to crack the blades open and hope I got it close. The next carb will be drilled for the .035" hole.

[rfoll]

The carb went down the road Saturday, although I'm sure I haven't seen the last of it. I couldn't make the secondary throttle plat screw move. I soaked it, beat on it, heated it, and several combinations of those. I manufactured a hard steel screwdriver to fit the hole and it broke off. As an alternative I bent the tab to crack the blades open and hope I got it close. The next carb will be drilled for the .035" hole.

[rfoll]

The friend comes over with the carb installed. It runs like a top, idles well holds plenty of idle speed in gear. He loves the way it runs. He does not have his vacuum advance hooked up, so I grab some hose and make the connection to manifold vacuum. Idle speed goes way up requiring the primary blades to be closed more to get down to approximately 1100 rpm. He drops it in gear and it barely idles in gear. Now the out of gear idle needs to be too high to allow it to run in gear. I want to guess converter is about 3000 stall from the sound of things. Timing aside, the only thing changed is the primary throttle plate position. I'm thinking it might help to crack the secondary plates open further. I have never had anything like this ever happen because I always run a vacuum advance.

[F-BIRD'88]

Hook the vac advance to ported vac on the carb

[rfoll]

I wish, No ported vacuum on a 3310-1

[Horder]

My 3310-1 has one.

[rfoll]

Where? There is a nipple under the front fuel bowl and a larger one on the metering block. Both have vacuum at idle

[Horder]

Primary metering block on passenger side

[Horder]

Primary block is 5271

[novadude]

The Quick fuel adjustable vacuum pod also works excellent . I have used this. The baseline setting for the adjustable needle is 1.5 turns off the seat.
Quick Fuel Brawler BR67258 uses this along with the brass tube and dog leg boosters. The vacuum pod has a .065” brass orifice along with a purple spring and adjustable needle screw. I have tried this carb and found that it worked excellent , rated at 770 cfm. A little rich as delivered.

One thing I've wondered about those covers: With a check ball, when you are off the throttle, the check ball unseats and allows the space above the diaphragm to quickly return to atmospheric pressure. If you are restricting that opening, do the secondaries still close quickly? The mechanical linkage on the other side of the baseplate will still pull them closed, but I can't help but wonder why Holley would have used a check ball if a small orifice worked fine?