Rebuild to Zenith's completed: Base plate question

[MunichTaxi]

I'm down to the base plates and have heard about the dreaded 'Warped base plates". Are these the heat shields?

I have decided to cut out my own gasket (between the intake and bottom base plate). The rebuild kit didn't provide a gasket, so I'm cutting out 1/32" thick gasket material.

BTW, the rebuild job was almost 15 hours (and their not in the W114 yet). Hardest thing is to keep track of the jets.

[230/8]

Base plate warpage typically refers to the carburetor base plate, the part the throttle shafts run through. There are very thick asbestos base gaskets between the carbs and manifold that also have a heat shield sandwiched in the middle. I suppose these heat shields could warp, but the thick gaskets and tight clamping nuts should ensure they seal properly.

Warps in the carb bases usually are caused by removing the carbs when hot, but a stuck manifold heat riser can overheat them, too. Use a short machinest's straight edge to check whether the carb bases are warped. If they are then a machine shop can tell you whether it is possible to surface them a little bit to reestablish the flat gasket surface. It is also possible to true bases that are warped only slighty by using emery paper on a flat piece of plate glass. Some folks have used flat files, but they bother me. Too much material comes off too fast and it's hard to ensure you are keeping everything flat and true.

I think you can order those base gaskets. If you are sandwiching many sheets together to make a thick (1/4 inch more or less for each side of the heat shield) then you just increase the number of places where a vacuum leak could occur.

Hope this helps,

230/8

[autozen]

You didn't specify what you were working on, but looking at you stable list, I'm assuming you are working on a 114.011 prior to 72 which means you are working on a set of Zenith 35/40 Inats. If you had a 72, they would be 32/40s. I don't understand what base plates you are talking about. There are several points that must be set up on these carbs to make them function properly. The most important points are; choke flaps closing, pre throttle gap, and synchronization of the two carbs. I think these carbs were the finest ever built, but they need to be understood. I was trained on them by a star technician from Germany many years ago, but alas most of those cars are gone. A few months ago I had the opportunity to set up a pair at a friend's shop for one of his customers. It was a beautiful 250C.

I'll try to answer your questions, but it is difficult by typing. These carbs really need a hands on feel to set them up properly. I can't explain how to tweak up the springs in the choke housings to get full choke closure to draw maximum fuel to start the car. Then pre throttle gap must be perfect or the car will cough and crap out when you try to drive it cold. When these Zeniths are set up properly, you should be able to fire up the car and back it up or drive it away without a stumble.

Good luck,
Peter

[MunichTaxi]

I do have a Devellorta (sic) scynchrosier that works well for these carbs. I set up my W108 this way.
The exhaust manifold 'heat' flaps don't work, so they are permantly set in the closed position. It doesn't get too cold around the Puget Sound.

As I said before, my huge 'backyard mechanic' mistake was to reverse the retard and advance vacuum hoses on the 3 way valve.

Thanks for the info, 230/8. Now I know where to install my thick 'custom' gasket.