Zenith on 914-6 Options

[DennisV]

What are the challenges with using Zenith 40 TIN carburetors on a 1970 914-6 engine?

My understanding is Weber 40 IDTP would be the correct original carb. I also understand that 1970 911T came with this model of Zenith. So in theory, no problem?

We are trying to decide if we should rebuild these Zenith. If they are essentially same fit, form, function as the Weber, we will probably keep them. If there is some domino effect of now that you're using Zenith you also need to replace / modify x, y, and z, then we will probably try to source some Webers.

Thanks for sharing your experiences.

P.S. Would I be correct in understanding that the key concern when evaluating the carbs for rebuild would be:

1. Throttle shaft bearing wear
2. Floats that leak

[914Sixer]

Parts is the biggest problem. Personally I like them. Not sure but I think Porsche Classic has reproduced some of the parts. You are correct on problem areas.

[Retroracer]

Parts is the biggest problem. Personally I like them. Not sure but I think Porsche Classic has reproduced some of the parts. You are correct on problem areas.

(IMG:style_emoticons/default/agree.gif) The TIN40s are essentially "bolt on" compatible with the Webers - throttle linkage, manifolds, air filters etc - but you may have to optimize the jets to run with the 2.0 (if the carbs were from a 2.2) and the modern fuels we have available. Idle and main jet options are easily obtained, but some of the parts can be tough to source. For instance, the eccentric cam roller bearing that activates the acceleration pumps was seized when I got my carbs, and I could not find a source for a new one at the time. So I had some machined up.

Properly rebuilt and set up, they have proven very stable and reliable, FWIW. There's some good online info about setting the floats on reassembly, and of course, check float levels and such like you would a Weber and you should be good to go.

Interesting call on whether to fit "what's on hand" (ie. the Zeniths) or spend the $$ and replace with the correct Webers. If its an original 6 - with values buoyant as they are - it might be worth searching for some Webers and just sending me the Zeniths to use as spares.... ;-)


- Tony

[DennisV]

Interesting call on whether to fit "what's on hand" (ie. the Zeniths) or spend the $$ and replace with the correct Webers. If its an original 6 - with values buoyant as they are - it might be worth searching for some Webers

I am still on the fence. The car is an original 914-6. The engine is the correct serial number range, but not the original one that came with our car. If it were all numbers matching I would make the leap for the Webers.

The car is in really great shape, but just rebuilding the engine and transmission are going to be pretty significant bills. It's looking like sourcing IDT Webers could add another ~$4k to the equation. We have Bosch distributor that best I can tell came from a 911S, so I will probably need to replace that another $500?

Guess I will try to evaluate these Zenith and see if they are even worth rebuilding and go from there.

[Retroracer]

We have Bosch distributor that best I can tell came from a 911S, so I will probably need to replace that another $500?

Whats the part number on the Bosch disty? It would be useful for you to know what the build details are on that engine. For instance, if a PO has fitted "S" cams and pistons, then MAYBE they fitted the S disty to match the cam; on the other hand, if its the original "T" cam, then you should probably get that unit recurved / replaced...?

- Tony