Technical Hole in Holley 94 carb help

I have 2 matching Holley 94 carburetors (model 59), matching except one has this hole and the other does not. I was asked what the purpose is for the hole. I asked my friend and neighbor who used to rebuild 94s for years but he'd never seen it before, that he could recall. I have no doubt the answer is somewhere here on the HAMB but I have spent hours reading posts (really good information) but so far I've not found it. On a Marts Garage video where he tears down and reassembles two 94s he mentions the hole when comparing the two carbs but does not go into any detail on why it's there or if it's necessary. Any help is greatly appreciated on why it's there and the reason behind it.


Larry

 

That is a vent hole.

 

@Mart
@carbking

 

As Flatjack said. First vent hole was in front of the air horn. Fan caused turbulence, or so I’ve read, that required a different location for vent. Final version of vent was a tube down the throat.

 

I believe that a spring and a plug go in that hole to hold the choke linkage in position.

 

Is this the same hole ?

This is a later model carb I think ? looking at the choke thing on the other side of it and spark arrestor. Maybe one of the last ones used.

Is it possibly the wrong top on your carb ?

 

Good question Larry. Seems like I have a couple tops with the hole in my parts box. I've never had need to use them yet but it would be good to know the why's and wherefores for the future.

 

As others have mentioned, it is a vent.

There are VERY FEW MATCHING Holley AA-1 (marked 94's) left in our solar system, due to them being rebuilt by commercial rebuilders.

Jon

 

sure looks like a big hole for a vent but that is what I have heard they are also.

 

Thank you for the info. Should I swap tops so that both carbs have holes or both carbs have no holes or does it matter?

Larry

 

My use of the term "matching" is very, very, very loosely defined!! Hahaha!

Larry

 

I bought a box of carbs and noticed the holes. I wondered WTH and if it was a box of junk. So, is there a plug and spring intended for these holes?

 

No plug or spring, it's just a vent hole. I haven't found out the why's of it though.

 

It would appear I was looking at the wrong hole when I answered that question last night. Sorry for not being as observant as I should have been and giving out mis-information.

 

Since you have tops, I would suggest that both match.

I really don't think it would matter; but from a theoretical standpoint, having vents in different areas could cause a minor discrepency in the pressure above the fuel in the two bowls. This MIGHT have a small effect on idle condition. Again, I don't think it would; but since you have the tops, easy to match them.

Jon

 

Awesome! I'll do that, thank you.

Larry