You've got the double vent bug?

Posted by MRR on Sep. 15, 1998 at 08:35:24

In Reply to: 1928 Zenith with Brass fittings
posted by Kevin Daly on Sep. 14, 1998 at 10:29:02

Be careful!You can become addicted to carburetors.
Check for the boss where the pin to hold the internal venturi as an indicator of being a double vent in a former life.The boss may be found on either the side of the carburetor.Another indicator is that most of the doubles had the secondary well machined into the casting rather than the replaceable brass that the later carbs had.Because the parts have been mixed and matched so much it is possible to have a double top or bottom matched with a later version.
The double venturis themselves can be hard to find and are expensive.A&L (maybe A&S) in Conneticut makes them and they work well but they cost about $30 each.I have three versions of the double that I use on my early '29.
The double venturi works very well.My Holley version will get exceptionally good mileage and performance is very good.Many of the A people don't pursue them because they say that there must have been something wrong with them because Ford changed them early in production.My personal opinion regarding why Henry changed was that A) the single venturi carb is cheaper to build and B) some improvements were made to the later carbs (the replaceable secondary well helps from a maintenance standpoint).People that want the correct carburetor for their AR or near AR car will pursue them.The double has a different "whistle" than the later singles so get ready for people to ask what's going on under the hood when your sitting there idling.
As far as value, the mechanics of the Zenith have more to do with the value of the core casting than it's version.Yea, I know the Zenith 2 & 3 stories.Check to make sure that you have a good idle seat in the top.A carburator that will idle properly is worth more than the junkers.The doubles are somewhat more rare than the later units so if your looking for one you would expect to pay a little more.I've found castings at swap meets in usable condition at prices ranging from $10 to $50 (depending on what is there).Rebuilt unit prices are a different market that subject you to the honesty and workmanship of the guy doing the work.
If your interested in further discussions or need some help, give me an e-mail.
It's a great hobby ain't it?MRR

Follow Ups:
Re: You've got the double vent bug? Kevin Daly Sep. 17, 1998 at 07:09:38(2)
It all comes down to money. MRR Sep. 17, 1998 at 08:35:42(1)
Re: It all comes down to money. Kevin Daly Sep. 17, 1998 at 09:31:43(0)

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