off idle stumble

Mike Savelle · 08-01-2021, 05:15 PM

installed a Holley 3310 on our crate motor and it stumbles bad when staging , but when it gets to 2700 it smooths out and had our best 1/8 mile pass on this motor . Any help appreciated . Mike

L.Fite · 08-01-2021, 06:52 PM

Carb stumble/bog,
Things to check...
Accelerator pump adjustment.
Squirter size.
Vacuum secondary opening rate.

Eman · 08-02-2021, 09:30 PM

On my 3310 making sure the transition slots on the primary side aren't exposed too much. Flip the carb over and see how much of the transition slot is showing on the primary side. If it's more than square look at the secondary slots. If the secondaries are covering the transition slot open the blade adjustment enough to square the slot. Then you can lower the idle screw and go from there. Might still need to richen idle screws and possibly increase squirter size. Be sure to adjust the spring on the acc. pump lever and if needed put a diaphram and check valve in the pump.

Ralph A Powell · 08-03-2021, 07:47 AM

Not more than .060 of the slot showing. Does throttle blades have holes in them for more air at idle?

Dyno · 08-03-2021, 10:32 AM

Bump the squirter up to a 35 or 37. Use the purple spring in the vacuum diaphragm.

6130 · 08-04-2021, 12:57 AM

The 3310 is an awfully forgiving carburetor- I've used them on everything from 302s to 460s, and they've always worked great, right out of the box...

08-01-2021, 05:15 PM	#1
Mike Savelle Member Join Date: Dec 2001 Location: Ontario Canada Posts: 369 Likes: 125 Liked 7 Times in 5 Posts	off idle stumble installed a Holley 3310 on our crate motor and it stumbles bad when staging , but when it gets to 2700 it smooths out and had our best 1/8 mile pass on this motor . Any help appreciated . Mike

08-01-2021, 06:52 PM	#2
L.Fite Senior Member Join Date: May 2020 Posts: 519 Likes: 561 Liked 498 Times in 244 Posts	Re: off idle stumble Carb stumble/bog, Things to check... Accelerator pump adjustment. Squirter size. Vacuum secondary opening rate.

08-02-2021, 09:30 PM	#3
Eman Member Join Date: May 2014 Location: E TN Posts: 473 Likes: 16 Liked 133 Times in 76 Posts	Re: off idle stumble On my 3310 making sure the transition slots on the primary side aren't exposed too much. Flip the carb over and see how much of the transition slot is showing on the primary side. If it's more than square look at the secondary slots. If the secondaries are covering the transition slot open the blade adjustment enough to square the slot. Then you can lower the idle screw and go from there. Might still need to richen idle screws and possibly increase squirter size. Be sure to adjust the spring on the acc. pump lever and if needed put a diaphram and check valve in the pump.

08-03-2021, 07:47 AM	#4
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 390 Likes: 2 Liked 226 Times in 137 Posts	Re: off idle stumble Not more than .060 of the slot showing. Does throttle blades have holes in them for more air at idle?

08-03-2021, 10:32 AM	#5
Dyno Senior Member Join Date: Dec 2002 Posts: 920 Likes: 1,148 Liked 694 Times in 206 Posts	Re: off idle stumble Bump the squirter up to a 35 or 37. Use the purple spring in the vacuum diaphragm.

08-04-2021, 12:57 AM	#6
6130 Member Join Date: Jul 2012 Location: Texas Posts: 409 Likes: 295 Liked 117 Times in 50 Posts	Re: off idle stumble The 3310 is an awfully forgiving carburetor- I've used them on everything from 302s to 460s, and they've always worked great, right out of the box...