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aka 'vageen'
 
unclebilly's Avatar
 
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34mm venturis for Zeniths? Anybody want a set?

I am getting some 34mm Venturis made up for some Zeniths. These will be CNC machined and a big chunk of the cost is in the programming.

I am hoping to get one or 2 extra sets made up to amortize the programming costs over 18 parts instead of 6.

Who is interested in a set at $150/set of 6 shipped in Canada / USA? These will be made from 6061 Aluminum and will drop into your Zenith 40 TIN carbs with no modifications.

I have no idea what MotorMeister chages for his. I know that PMO charges $100 for a set of 6 for Webers but he is working on a bigger target audience.

I am getting 34mms done because these work with a 2.7L engine used for track / or a 3.0L for street use.

Let me know if you are interested. I am going to pull the trigger on quantity this afternoon. I should be in a position to ship these by Thursday.
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Old 03-05-2012, 09:50 AM
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You can use Weber Venturis with a small gasket to make up the difference in height. Weber venturis are shorter than Zeniths'. Seems a lot cheaper to me. Plenty of Weber Venturis out there.
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Old 03-05-2012, 01:15 PM
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You can do that but weber venturis dont have the steped OD. The upset in diameter from the O Ring in the flow path will introduce some turbulence (not what you want at high RPM), In reality, Weber venturis are $100 for the set + shipping and don't fit perfectly. For only a few bucks more, you get the right thing.

These will fit perfectly.I got an extra set made on spec. I will post photos once I have them in hand. I did this to help out a fellow enthusiast, not to make a buck.
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Old 03-05-2012, 02:03 PM
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Here is another source:

Venturis
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Old 03-05-2012, 03:27 PM
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Obrut - those look real nice, and a lot like mine...

Porsche 911 Zenith 40TIN Carb 34mm venturis, 2.2L, 2.4L, 2.7L, 3.0L, set of 6 | eBay

I have 1 extra set of 6. Combine these with the appropriate jets (65 idle and 160 mains) depending on altitude and displacement, and this will be a nice upgrade.
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Old 03-09-2012, 06:10 AM
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This is how they look:



vs the stock 27.5 venturis:

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Old 03-09-2012, 02:04 PM
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Weber venturis have their waist at 8mm from the top and Zeniths have their waist at 13mm from the top. Both are 45mm high which means the waist of the Weber is higher in the Zenith throttle body by 5mm. Not much but the waist is by design located where the bottom of the auxiliary venturi is which means the Weber will develop its minimum pressure above the height where the Zenith would have it. The result is that the efficiency of fuel delivery onto the main circuit is compromised.
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Old 03-09-2012, 02:37 PM
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Quote:
Originally Posted by 1QuickS View Post
Weber venturis have their waist at 8mm from the top and Zeniths have their waist at 13mm from the top. Both are 45mm high which means the waist of the Weber is higher in the Zenith throttle body by 5mm. Not much but the waist is by design located where the bottom of the auxiliary venturi is which means the Weber will develop its minimum pressure above the height where the Zenith would have it. The result is that the efficiency of fuel delivery onto the main circuit is compromised.
Agreed.
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Old 03-09-2012, 03:34 PM
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Venturis for Zeniths

I would be interested in a set if you can ship them to Italy or Barbados

Andre
Old 03-17-2012, 10:03 AM
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I have had a few people inquire about these since I sold the spare set on ebay.

I do have access to 3 more sets that are 2nds. The machine shop accidentally didn't put the correct diameter on the top flange. Internally, these should be OK however the top flange is a smaller diameter that it would be for a perfect fit.

These will be better than Weber venturis and will drop in and work fine.

I can probably get these from the machine shop for $60 / set + shipping.
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76 930 Original
77 911S Wide Body GT2 WCMA race car
86 Slantnose 930
Yoosta have: 90 C4 Targa, 87 944
Old 03-25-2012, 11:11 AM
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Last call...

Porsche 911 Zenith 40TIN Carb 34mm venturis, 2.2L, 2.4L, 2.7L, 3.0L, set of 6 | eBay

These are te 3 sets of 2nds.
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Yoosta have: 90 C4 Targa, 87 944
Old 03-29-2012, 01:33 PM
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I would very much like a pair as well. I'm from Calgary and will be back there in January. Maybe we can arrange something? Do you think I could call the machine shop and have them manufacture some for me?
Old 11-20-2012, 07:14 PM
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I don't know if he still does it, but I had Jeremy on this board (username: "pcar9119") build me a set of these a while back... very nicely done- they fit perfectly (with just an ever-so-slight interference fit) and Jeremy accounts for the higher waist needed in the Zenith carbs vs. the weber venturis. It's nice to see new parts for these carbs beginning to emerge- when I got mine done, there really weren't any other sources beyond getting them custom machined! Maybe someone will start making emulsion tubes?

Curt
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Old 11-22-2012, 07:42 AM
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We made our 34 and 36mm Venturis with the waist at 13mm.

We have also made Weber and Solex 40PI Venturis with 8mm waist and 10mm waist respectively.
Old 11-23-2012, 07:18 AM
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34mm

count me in for one set!
Old 11-25-2012, 02:43 PM
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Still Available?

Are any of these venturies still available? I am running Zeniths on an otherwise stock 2.7. I am currently using Weber 32mm venturies from PMO but have a stumbling issue above 4000 RPM. Would 34s be okay? What jets are people using? Thanks, Andy.
Old 11-26-2012, 07:24 PM
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Any chance these 2nds are still available? I would like a set.
Old 11-26-2012, 08:22 PM
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Seems like there is still quite a bit of demand for these.
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Old 11-27-2012, 05:51 AM
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yep

Yep. I think some more people would buy some. I wonder if unclebilly's machine shop still has the specs?
Old 11-27-2012, 04:11 PM
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Hello,
I have a question about Venturi's for Zenith. I got my carbs apart, and I found pretty odd that while the bore is 40 mm, the outlet diameter of the venturi is only 36 mm or so. As a result, there is a jump right after the outlet of the venturi and immediately before the throttle plate. I'd like to make my own 30 mm venturi's, and I think it would make sense to have the outlet with 40 mm ID, just like the throttle bore to avoid steps in such a critical area.
Any reason why Porsche left this big step there? My guess is that they wanted to mantain a smooth angle in the expanding part of the venturi, and probably there isn't enough room to increase the diameter from 27.5 to 40 in only 35 mm. Currently the angle is about 10 degrees, which is relatively big.
thank You
luca
Old 01-28-2013, 12:50 PM
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