Double Venturi carb Before/After
- Thread starter Gary WA
- Start date
Dave in Petaluma
Member
Gary, where will you find a new venturi for that carb?
Gary WA
Well-known member
I have a few and I did that one for someone else who has one. They were available thru the vendors but supply is out.!
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Synchro909
Well-known member
Does a single venturi fit the housing?
Gary WA
Well-known member
yes they will,read where they were changed in late 1928 because mechanics were breaking them when taking apart so changed to single venturi. never tried to run a DV with single not sure on the operation.
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Gary, were there original jets in this double venturi carb and what were they numbered/sized? Didn't Holley/Zenith change them a few times? I ask because I have some jets and don't know for sure what number Zenith (1 or 2) to stick them in. Also, your article on secondary carb wells printed in the national mag was great! Thanks LRF
johnbuckley
Well-known member
Originally jets were numbered replacements generally aren't. Flow testing is the only way to ensure accuracy of jets; various articles elsewhere on Fordbarn about that topic!
If going by numbering Idle usually 10 or 11, Main19.5 or 20, Comp 18 or 19, Cap 19, 20, or21 jets are interchangeable on SV and DVs and Zeniths I and 2 and Holleys lookalikes ,
If going by numbering Idle usually 10 or 11, Main19.5 or 20, Comp 18 or 19, Cap 19, 20, or21 jets are interchangeable on SV and DVs and Zeniths I and 2 and Holleys lookalikes ,
johnbuckley
Well-known member
I have run DVs in "single venturi" housings and vice versa and detected no difference in performance or economy. You may need to grind the locating dowel off if fitting a SV to a DV housing.
Jim/GA
Well-known member
Stromberg vs. Zenith April 1928
https://casetext.com/case/stromberg-motor-devices-co-v-zenith-detroit-2
Synchro909
Well-known member
Good stuff. Thanks guys. I have a KTK carburettor which is DV. I'd like to get it going - just coz. IMO a Japanese carburettor on the Model A would raise a few eyebrows.
RENNERS CORNER
Member
Holley / Zenith Double Venturi.... found another core to assemble and run. Here again someone removed the locator / indexing pin. The pin is another item I need to reproduce as many were ground off or tapped out so that a later venturi could be used.
Back when my dad and I used to rebuild carburetors as a service, we would only get maybe 1 or 2 a year.
I wonder how many of these dual venturi upper and lower castings are still out there?
Back when my dad and I used to rebuild carburetors as a service, we would only get maybe 1 or 2 a year.
I wonder how many of these dual venturi upper and lower castings are still out there?
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Joe K
Well-known member
RENNERS CORNER
Member
I'm not so sure about that.... I would be interested to know where you read that.
I don't know why that many mechanics would already be working on them in the first 6 months that the car was being built.
What I have read about the DV is that Ford was faced with a potential lawsuit from Stromberg, that is a well documented reason for changing.
I also believe that there would've been Ford service bulletins about this with Ford advising their dealers to replace or be mindful when working on the DV carburetors.
I'm sure at the Benson library there's an Engineering Information sheet that explains this, too bad we can't get back in there....
rackops
Senior Member
I'm sure plenty of them...a guy at Hershey in 2024 had a bucket of double venturi cores. No venturis, but the cores...a lot of them (I picked up a few).
It just all depends on whose collection is being sold off this year...
alexiskai
Well-known member
That "explanation" appears in Gordon Biggar's book on carbs ("the Rex Reheis way"). He doesn't give any further details, just that one sentence.
RENNERS CORNER
Member
I knew / know both of those guys that worked on that book.
I think like a lot of old timers they always have some bit of folklore / wives tales mixed in with their explanations.
I can't believe that mechanics were breaking that many of them so early on, that's just unbelievable and then to not have any mention of it in service bulletins....
Thanks for the reference though, I'll ask Mr. Biggar about it.
alexiskai
Well-known member
What he says in the book is that mechanics would twist the halves of the carb to break them apart, which would crack the venturi. Even if this were true, the solution would have been to tell mechanics not to do that, not to redesign the carb at great expense.