67 Holley 3810 carburetor question.

[Chuck M.]

I am having my Holley 3810 carburetor rebuilt and have a question regarding the configuration of the secondary bowl. I have attached two photos, one showing a vent hole in the bowl (not mine) and one without (mine). I took the carburetor off the car to have it rebuilt because it was leaking everywhere. When my restorer received it he made a comment that there should be a vent hole on the secondary bowl. The car this came off of is a Duntov award recipient and has been judged Top Flight several times and it has never been mentioned that the vent should be there. I have also asked fellow members if they have seen it or if their carburetor (3810,3811,3814) is configured this way and the common response is I haven't seen that before.  I also looked in Nolands book and didn't see any photos or references made of this vent hole.

Can someone explain what this hole is for and what configuration is correct for a 1967 corvette that used a 600 cfm carburetor? Are both configurations acceptable?

Thanks.

[Jeffrey S.]

Re: 67 Holley 3810 carburetor question.

I have a 67 with what I think is the original carb and it does not have that " vent " cast into the bowl before the H in Holley. Hope this helps Jeff

[Chuck M.]

Re: 67 Holley 3810 carburetor question.

Thanks Jeff. I really don't know that I have ever seen it when judging or OJing. At this point I'm not going to change anything but now I'm just curious.

[Michael M.]

Re: 67 Holley 3810 carburetor question.

The picture of the first float bowl looks like a original bowl for a 3367 carburetor that was used for the 327/350 hp engine.

[Chuck M.]

Re: 67 Holley 3810 carburetor question.

Hey Michael, yeah I thought about the possibility of that hole being an earlier design used on 65/66 cars but I have nothing to substantiate that theory. Thanks for the data point.

[Chuck M.]

[Bill M.]

Re: 67 Holley 3810 carburetor question.

Sure I have a 65 and 67 will check when I get home

[Peter M.]

Re: 67 Holley 3810 carburetor question.

Chuck,
My 67 with 3815 carb does not have the casting you are asking about.
Kind regards.

[Peter L.]

Re: 67 Holley 3810 carburetor question.

Chuck - The Holley 3810 (date 682) on our Sept 1966 build '67 300hp/327 4spd car has only the HOLLEY logo on the face of the back of the secondary bowl. Pete

[Leif A.]

Re: 67 Holley 3810 carburetor question.

Chuck,
My '67 L79 with Holley 3810 is as Pete describes.

[Chuck M.]

[Michael C.]

Re: 67 Holley 3810 carburetor question.

My '67 3810 does not have that hole, however, my '65 2818 does have the hole.

[Chuck M.]

Re: 67 Holley 3810 carburetor question.

Thanks for the help Michael, I really appreciate it.

[Michael M.]

Re: 67 Holley 3810 carburetor question.

My April built 1966 L79 has the hole in the secondary float bowl.

[Gerard F.]

Re: 67 Holley 3810 carburetor question.

Chuck,

Take a look here:

https://www.forums.ncrs.org/showthread.php?96083-1966-Holley-3367-carb-need-help&highlight=Holley+Fuel+bowl+boss

This post is about a 3367 vs 3810 but after post #15 we get into a discussion of the circle/plug in the secondary fuel bowl on a 3367. On a 3367 there is also a circle/plug on the bottom of the secondary bowl, as well as a screw/ sight hole on the side of the secondary bowl to adjust the float level.

If you have the sight hole on the side of the secondary fuel bowl (like other 65-66 chevy cars) it is not for a 67 corvette 3810.

The circle/plug on the back side of the bowl and bottom, and the sight hole are for the external adjustment fuel bowl.
For the 67 corvette and other models, GM in their economic wisdom, decided to cheapen things and went to the non-externally adjustable fuel bowl. This eliminated the adjustment mechanism, sight hole and screw. To adjust the float level, you now had to take the bowl off. This pain in the neck change saved some money, and may be associated with the beginning of emission standards.

The change in the Holley was made for the 67 model year. However if your 3810 is very early in the 67 model year in 66, it may have the 3367 fuel bowl modified for the 3810.