Zenith 40 TIN
 

Does anyone know the butterfly angle on a Zenith 40TIN?

I am thinking about boring a set to 44 or 45mm and I can buy throttle butterflies from a 45DCOE which is 78 degrees very cost effectively.

I also need to buy some inlet manifolds and thought that Motormeister 'Monster' inlets looked good at $400 but so far they have resisted all attempts to place an order. :)

PMO would be a good source for intake manifolds. You have to fax Mr. Parr. His price is listed at $400.

Don't know about the angle. If you mean the angle at idle, I don't know. 78 degrees seems close, but it could be larger. You could measure the two extreme edges of the butterfly, relative to the base flange surface with a depth gauge, and calculate the angle from there. Seems the most direct way.

Never heard of anyone boring out the Zenith TIN body, I'd be interested in your results. Keep us posted if you proceed.

I looked into this last year. Emailed the guy in Italy that sells jets for the Zenith and Webers on ebay. He said there were no butterflies available for the Zenith and the Weber butterflies were the wrong angle. Look at the seating of the butterfly, there is a very small hole that is closed off when the butterfly seats, this is the challenge. He had not heard of anyone boring the body larger and wondered what the passeges behind the wall would look like.

That being said, I would think it could be done. I didn't continue because I had too many irons in the fire already.

Please post pictures as you progress.

Thanks,

I have heard stories of them being bored to 44mm and I guessed I was being optimistic about the butterfly angle.

I will look at alternative Solex butterfly discs and see what is available and what the angle of these may be.

I suppose I could make new spindles with a different plate angle and solve the porblem that way.

Perhhaps buy 50mm butterflies and machine the correct angle. You could make a lathe fixture that would be mounted using the screw holes and is angled so it is just a simple diameter turn.

Neil,

Good idea, I think I will just get some discs waterjet cut as if we have to make a fixture we may as well juat make the entire thing. :)

Please let us know , if you ever get any large bore zeniths up and running.

Thx

Porsche Leather Work and Zenith Carburettor Manual.

This was posted a while ago on the engine rebuilding forum

Hope it helps

Errie Kruger

I have a junk Zenith body, or two. I've been meaning to dig into them to see if they could be brought back to life, but I am beginning to doubt I'll ever get to it. Let me know if they might be of use to you, perhaps for "exploratory machining."