I know it seems just a bit ignorant to put a 750 cfm carb on a 305 Chevy even if it's vacuum secondary, but I got the carb for such a good deal, I couldn't pass it up. I was hoping I could down size the jets, put a stiffer secondary spring in it, and use a small accelerator pump nozzle and tune it to work. Has anyone successfully made this happen, or am I just chasing my tail? I tried #65 jets, #50, and I will be trying some brand new #55 this afternoon if they will ever get here. Even tried #40, but it wouldn't even run with those. It idles fine with the 65s and 50s, but falls on it's face when I try to gas it some. Adjusted the accelerator pump proper, and it isn't much better. I just set the timing, but figure I should make sure it is still on. Just looking to see if anyone knows what the magic combo is, or if I should just sell it and get a 1850.
3310 - Is it too much carb for sure on a mild 305?
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65 was the first set of jets I had in it. I tried 40s and 50s and I just put 55s in it, but haven't got to start it because I have to pick up my son, so I will try it when I get back home. I figured it was stumbling because the 65s were too big for it. Right now it has a mild cam and performer EPS intake. Am I going the wrong way with it?
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40 main jets? You know Holley carbs aren't jetted in steps of 5 (.05 mm) like a Weber.
Be lucky if it would respond to the main circuit at all with such tiny mains. You really need a 550 - 600 VS.
The largest issue you have is the venturi has poor booster signal, since is on the large size for the engine.
The most important part of selecting carb components is venturi sizing. GaryRegards, Gary
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This is a video of what it's doing: https://youtu.be/mKRSImEEjoE. Same thing with the 55 jets and the 65 jets. Idles fine.
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Yes, that's bad and undriveable. Are the float levels correct?
And I could bet you could go rich on the mains at 80s, and it would still do this.
Keep it if you want to for the future, but this engine needs a smaller carb.
If you want to stay with a Holley, a 650 spread-bore 4175, a 4010 600 VS, a 550 as above, etc., would be better choices. GaryRegards, Gary
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Well, very long story made short; the 1850 didn't work so I traded the guy back for the 3310. I decided to give it another go, but I swapped out the metering plate on the secondaries for a metering block I had, then tried to tune it better. At this point it had #65 jets in the primary. It was running real lean. I put some 68 jets in and it ran decent. I'll get a gauge and check my AFR and see if I need to go any different on it. Idles great and doesn't stumble much when you floor it. It's driveable!
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