Holley 3310-2 tuning
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Joined: Nov 2016
Posts: 51
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From: Houston
Holley 3310-2 tuning
Guys,
I have a 750CFM sitting atop of an Edlebrock airgap intake on a mostly stock 350 from 1978. I have been turning down the mixture screws to try to lean it out, but still running rich. I am at about one full turn off base.
It also has a serious hiccup and cough when you hit the gas at all, so I am thinking the prior owner (who had a single plane intake on it) may have also fussed with the jets. Can someone give me an idea of the jet size you think would be a best match for my setup. I drive only on the streets and mostly in areas where 45 is the top speed. Thanks all.
I have a 750CFM sitting atop of an Edlebrock airgap intake on a mostly stock 350 from 1978. I have been turning down the mixture screws to try to lean it out, but still running rich. I am at about one full turn off base.
It also has a serious hiccup and cough when you hit the gas at all, so I am thinking the prior owner (who had a single plane intake on it) may have also fussed with the jets. Can someone give me an idea of the jet size you think would be a best match for my setup. I drive only on the streets and mostly in areas where 45 is the top speed. Thanks all.
Pro
Joined: Aug 2010
Posts: 648
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From: Napa, CA
Yes, check out your ignition situation first. You’ll need to pull the carb off to check out how much transition slot is exposed at your current curb idle setting. If anything more than what appears to be a small square, your primary throttle blades are open too far. Adjust accordingly and re-baseline your idle mixture screws to 1 1/2 turns out. Restart the engine and if it will not idle well with mixture screw adjustment and or more ignition advance then get out your drill motor and bits. You’ll need to remove the carb and drill two small holes in your primary throttle blades on the side that’s closest to the transition slot. I usually Start with 1/8”. Or, you can hit the secondary throttle shaft adjustment screw on the underside of the carb baseplate about a quarter turn or so to allow more air flow without richening it up. Lots of how-to DIYs on doing this on YouTube.
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Joined: May 2006
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Guys,
I have a 750CFM sitting atop of an Edlebrock airgap intake on a mostly stock 350 from 1978. I have been turning down the mixture screws to try to lean it out, but still running rich. I am at about one full turn off base.
It also has a serious hiccup and cough when you hit the gas at all, so I am thinking the prior owner (who had a single plane intake on it) may have also fussed with the jets. Can someone give me an idea of the jet size you think would be a best match for my setup. I drive only on the streets and mostly in areas where 45 is the top speed. Thanks all.
I have a 750CFM sitting atop of an Edlebrock airgap intake on a mostly stock 350 from 1978. I have been turning down the mixture screws to try to lean it out, but still running rich. I am at about one full turn off base.
It also has a serious hiccup and cough when you hit the gas at all, so I am thinking the prior owner (who had a single plane intake on it) may have also fussed with the jets. Can someone give me an idea of the jet size you think would be a best match for my setup. I drive only on the streets and mostly in areas where 45 is the top speed. Thanks all.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
The discharge nozzles on those carbs are pretty lean (#25), and will often result in an off-idle hesitation. If you have a hesitation after assuring that you have correctly set your accel pump lever adjustment, set your float level, balanced out your primary and secondary idle speeds, and properly set your timing, you can bump the shooter up to a #31 and see if the hesitation goes away.
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Holley's website has a listing of all their carbs and what jets, PV's, squirters etc they came with. On an unknown carb that someone may have been messing with...it's usually good to get it back to baseline and go from there.
JIM
JIM
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Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
That's not correct. The stock QJet carbs are 750, with many of the 1975+ Q-Jets installed on the 350 L82 being 800 cfm. The LT1 350s came with a 780 Holley, as did the 302 Z28s. Carb size has little effect on tuning and setup - I regularly set up and tune 1050 Dominators on my 357 test engine - no problem. A larger carb will actually run leaner than a smaller carb, so his "rich" issue has noting to do with carb size. A 750 4160 VS is a great performance carb to use on a 350 (once you fix the secondary spring).
Lars
Lars
