Heya gang. I recently bought a par of used list 1849 Holleys when I looked them up they are listed as Holley 550's. I am gonna do a rebuild soon, but what I was wondering on these older carbs is can I do away with whatever that is for in the pic I attached? Not sure if thats actually needed or not. Its like a vent hole or something on one of the horns. Can I just take that off and maybe tap the hole and plug it?

hoping to get one of you Holley experts info on this

I'm a little fuzzy on the details, but I believe that is a vent to prevent problems at idle (the exact nature of which I'm unclear). If you want it to stayed closed, just bend the arm that opens it so it doesn't open at idle.

Thanks for the reply. I posted on Holleys forums as well, but havn't gotten a response from any one there yet either. I was hoping to get more info on wether I truly need them or not and if I do close it off what would I be affecting if anything. Newer carbs don't have them and I am not sure if these are needed on these. Gonna be puting them on an Eldelbrock tunnel ram set up eventually. At least I hope to because I cant really afford 2 new carbs lol.

Wow, that is a first for me. I haven't seen any Holley's with that and I have 2 600's that I had bought back in 1984. My brother had bought a couple of small Holley's, separately, from e-bay and I'm sure they don't have that either. I think they are 450's, 4160 style, since I know he was looking for carbs smaller than 600 to run a dual quad tunnel ram on his 502 BBC and I know he said they were in the four hundreds.

I emailed Holleys Tech support, but have not heard anything as of yet. Seems alot of people don't know exactly what it does or even what it is lol.

Well I got an Email back from Holley and this is what the sent.

(These are not necessarily needed if they have bowl vents in the mainbody. We do not suggest plugging these.)