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Initial Primary Float Setup

Old Jul 11, 2025 | 02:52 PM
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Default Initial Primary Float Setup

What's a good initial float setup for a recently restored 600 cfm Holley 3810 carb (my 67 327/350 original)? I've got things totally screwed up and pumping gas out of the stove pipe and the vent stopper.

How many turns for the needle and seat just for a starting point?. I'm afraid I'm going to blow up my garage if I don't figure it out. Of course I could move the car outside and scare the neighbors.

thanks,

Burnt Hair


'
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Old Jul 11, 2025 | 03:07 PM
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What about draining the bowl and then adjusting the top of the float to level with the bottom of the sight hole with a small screwdriver through the sight hole?
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Old Jul 11, 2025 | 03:35 PM
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Originally Posted by Tcheairs38655
What about draining the bowl and then adjusting the top of the float to level with the bottom of the sight hole with a small screwdriver through the sight hole?


Larry
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Old Jul 11, 2025 | 03:39 PM
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Tom, you can remove the bowl, invert it and set the float height per Holley specs with the adjustable needle, the reinstall it. Restart, check the fuel level in the bowl sight opening and make minor adjustments accordingly.
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Old Jul 11, 2025 | 05:27 PM
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Originally Posted by DansYellow66
Tom, you can remove the bowl, invert it and set the float height per Holley specs with the adjustable needle, the reinstall it. Restart, check the fuel level in the bowl sight opening and make minor adjustments accordingly.
with all this except if OP has an original List 3810 from '67, there should be no sight opening on the bowls.

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Old Jul 11, 2025 | 05:28 PM
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Originally Posted by DansYellow66
Tom, you can remove the bowl, invert it and set the float height per Holley specs with the adjustable needle, the reinstall it. Restart, check the fuel level in the bowl sight opening and make minor adjustments accordingly.
Dan, this is a 3810 carb and there's a long tube connecting the fuel supply to the secondary bowl. I'm not real sure how this tube releases the primary bowl. Yep, I need to remove the bowl and take it from that initial adjustment. Would appreciate any tips you may have for the removal of the connecting tube.


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Old Jul 11, 2025 | 05:33 PM
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A little off topic, but once you get this issue resolved, you might want to rid yourself of that "screen door" spring you're using for a accelerator return spring. The correct spring is readily available.
https://www.zip-corvette.com/63-67-3...r-67-auto.html


63-67 327 Accelerator Return Spring (Non Fi, 340hp or 67 Auto)
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Old Jul 11, 2025 | 05:36 PM
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The transfer tube is simply a push/light press fit into each front and rear bowl with an o-ring seal at each end. If you pull the front bowl off the carb main body, you will also pull it out of the transfer tube.

Larry
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Old Jul 11, 2025 | 05:42 PM
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Originally Posted by Tcheairs38655
Dan, this is a 3810 carb and there's a long tube connecting the fuel supply to the secondary bowl. I'm not real sure how this tube releases the primary bowl. Yep, I need to remove the bowl and take it from that initial adjustment. Would appreciate any tips you may have for the removal of the connecting tube.
I just looked at this picture again. Those fuel bowls are not from a '67 List 3810 Holley. They're from an earlier year Holley 4160...and, may have sight windows on the passenger side of the bowls. More interesting, where is the adjustment screw and nut on the front bowl?? There's one on the rear bowl but only a hole where the screw and nut should be on the front bowl. Fuel leakage anyone??
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Old Jul 11, 2025 | 07:05 PM
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Dan, No sight window. Just the brass screw plug. I removed the needle and seat to replace it thinking that might be my problem.
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Old Jul 11, 2025 | 07:06 PM
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Originally Posted by Powershift
The transfer tube is simply a push/light press fit into each front and rear bowl with an o-ring seal at each end. If you pull the front bowl off the carb main body, you will also pull it out of the transfer tube.

Larry
thanks Larry, I'll pull her apart tomorrow and go back to the drawing board with setting the float (dry).
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Old Jul 11, 2025 | 07:59 PM
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I haven’t had any problem with those fuel transfer tubes. They detach and reinstall pretty easily. My1850 use this type of tube seal but some use an o-ring. I’m not sure which the early Holleys used.


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Old Jul 11, 2025 | 09:44 PM
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The Holley web site has U-tube on your Holley to help.
https://www.holley.com/support/carburetor/
Scroll down to near the bottom of the page and open the sections up.
Ron
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Old Jul 12, 2025 | 08:24 AM
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Originally Posted by DansYellow66
I haven’t had any problem with those fuel transfer tubes. They detach and reinstall pretty easily. My1850 use this type of tube seal but some use an o-ring. I’m not sure which the early Holleys used.

Dan, what are you running an 1850? (1850S)? on?

Dan, what are you running the 1850 on?
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Old Jul 12, 2025 | 08:37 AM
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Originally Posted by R66
The Holley web site has U-tube on your Holley to help.
https://www.holley.com/support/carburetor/
Scroll down to near the bottom of the page and open the sections up.
Ron
Thanks for the link Ron
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Old Jul 12, 2025 | 10:01 AM
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Although not always successful at the installation, I have used O-rings on the tube for 50 years and with a little Vaseline and positioning the O-ring in the right spot before insertion, found it easy to do. Yes, the new cups are less fool proof, they are only a convenience upgrade IMHO.
Ron
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Old Jul 12, 2025 | 10:44 AM
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Originally Posted by Tcheairs38655
Dan, what are you running the 1850 on?
Tom, my engine builder provided them for the 2x4 intake on my ERA Cobra. They seemed to do fine but I was a little miffed I had to remove the bowls to my float adjustments. An especially pain when 2 carbs are mounted bowl to bowl. So I bought adjustable float bowls, new floats, etc and put on them.
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Old Jul 12, 2025 | 12:08 PM
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Originally Posted by DansYellow66
Tom, my engine builder provided them for the 2x4 intake on my ERA Cobra. They seemed to do fine but I was a little miffed I had to remove the bowls to my float adjustments. An especially pain when 2 carbs are mounted bowl to bowl. So I bought adjustable float bowls, new floats, etc and put on them.
Oh, OK..I see. I'm going to pull the primary bowl this afternoon and try to get the float level and go from there. My only fear is having a leak where the transverse tube inserts at the bowl.
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Old Jul 12, 2025 | 12:36 PM
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Originally Posted by Tcheairs38655
Oh, OK..I see. I'm going to pull the primary bowl this afternoon and try to get the float level and go from there. My only fear is having a leak where the transverse tube inserts at the bowl.
If the seals (o-rings or cylindrical rubber) are in good condition, just put a light coat of grease on the rubber when reinstalling the tube. The o-rings are not particularly special and your local Ace Hardware likely has them. Make sure you get Nitrile (Buna-N), Viton, or Teflon (PTFE) as these are gasoline resistant. Holley makes an
upgraded transfer tube upgraded transfer tube "o-ring"
that works quite well.

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