Zenith 40tin Modification questions

[cudabnu]

Anyone modify a set of Zenith's for a 3.0? Mainly looking for info on changing the venturies to 38mm to see how it is done.

[gregk1]

i was wondering the same thing on a 2.7 are you just able to change the jets???? they are not as workable as the webers as far as air flow goes what do you need to do as far as moving up???????

[Early_S_Man]

cuda,

Have you done the calculation to determine venturi size for your 3.0 using the power peak rpm? It would have to be somewhere north of 8000 rpm to need 38 mm venturis, and, if available, which is very doubtful for any 40 mm carb, they would look like tomato paste cans, being a nominal 1 mm wall thickness at the thickest point!!!

[cudabnu]

Sorry my mistake! 36mm. Actually I have been e-mailing Roy over at motormiester, he has been very helpfull and has sold me the parts I have not been able to get myself. The idle jets are unique to the zenith, the mains are the same as weber, and the porsche weber venturies can be used with a gasket ring since they are a tad shorter than the zenith's. I'll try to post pics as I re-assemble.

I think for my 3.0 i'm going with:

36mm venturies
65 mains
165 idle

[cudabnu]

Here's the new jets in place

[cudabnu]

Old Jets and mains/ spacers to use the Weber Venturies

[BK911]

I am interested to see how this turns out. Please post when you have it up and running. I have a set of nice zeniths sitting on a shelf and a 3.0 dying for some carbs.

[wv-geo]

cuda,
I'm getting ready to put together a pair of Zeniths for my 2.7 and have a few questions. Which parts did you get from MotorMeister? Where did you get the linkages, they look new? Where did you get the venturis and the gaskets for the venturis?

I contacted MotorMeister awhile back and the price I got from them for the venturis were $35/each. I am looking for alternatives to keep the cost down.

Thank you in advance.

[cudabnu]

The linkage and manifolds are PMO, the linkage will need to be bent a little to clear the accl. pump rods on both carbs it appears. I bought the main and idle jets and spacers for the venturies from MM. I ordered the 36mm venturies from Automotion.
I actually have one spare set of gasket kits (I bought a set and got a set from MM when I did a parts trade with them). I'rll probably be listing them for sale when I get back from Oregon on July 7th

[BK911]

MM told me they wouldn't sell the Zewnith parts anymore. It's either pay them $700 to rebuild your carbs plus the additional parts to set them up, or nothing. I forget the actual prices, but my conversation went something like this:

Me - I want to set a pair of zeniths up for a stock '80 small port 3.0.
MM - That's $2000 for the carbs and $500 for the manifolds.
Me - Whoa, I already have the carbs, I just want the parts to modify them for a 3.0.
MM - Ok, that's $700 for the carb rebuild, plus $500 for the manifilds and plus some for the conversion parts.
Me - Whoa, my carbs have a fresh rebuild so they don't need another one. I JUST need the pieces to convert to a larger motor.
MM - Ok, that's 500 for the manifolds and plus for the conversion parts.
Me - Ok, my existing manifolds are 32mm and I need 34mm. $500 sounds a little excessive.
MM - Ok, $1000 to rebuild the carbs for the 3.0 plus $250 for the manifolds. We sill not sell the parts individually.

My issue with this sales technique is not once was I asked what I had or what I wanted. Everything was about how much $'s I needed to give them before they knew what I needed. Once he realized I only needed some minor parts, he wasn't interested in helping at all.

Which is a shame. They found a nice little niche there that could help many people. Too bad their reputation and sales philosophy will probably keep many from using their services.

[cudabnu]

Here's a few more pics, Got the 36mm venturies with the spacer gaskets installed, tweeked the linkage a little, but still need to do more on the pass. side, it rubs at wide open throttle.