Zenith 40 TIN Carburator Questions

[FSJPorsche]

Can I use the carburetor tuning instruction in the Porsche 101 project book for Zenith carburetors?

When I purchased our 1971 Porsche last year, the prior owner said he had Weber carburetors. I thought they were Weber based on pictures. Problem with the carburetor and they are Zenith 40 TIN carburetors. They look almost identical.

One of the throttle plates is bent. Does anyone know where can I get throttle plates for a Zenith carburetor or can i just straighten out the existing plate?

Fuel pumps for a Zenith carburetor: Noticed that the pump for a zenith carburetor on the website is very expensive. The pump in my 1971 911E is an inexpensive inline pump. Could this be one of the reasons the car backfired and bent the throttle plate?

New to these types of forums and mechanically challenged.

Thanks

[pcar9119]

You can use the instructions in the book. As to the throttle plate bending, I guess a bad enouugh backfire could do it, but thats a bad backfire. As for your fuel pump issue, if your pump is starving the carbs, thats a problem. Carbs don't need high pressure, they need volume, maybe try to put a p;ressure regulator on it and see where your at, you only need about 4lbs of pressure for the Zeniths.

[LakeCleElum]

Any auto parts store will sell a fuel pump for under $30.....3-4 lbs is plenty...Straighten the plate if you can........I had many spare parts, but most are gone now to Pelican members.......Motor Miester sells parts, not cheap....

Biggest issue is to clean the carbs, clean the lines and fuel tank.......G luck......

[hessel1974]

For the fuel pump, the best alternative to the stock Bosch unit is a Pierburg brand pump. This has the same pressure as the original, but at a fraction of the price. And quality wise, it's german build Here in europe you will pay roughly 125 USD for such a pump.

[FSJPorsche]

Thanks for your help and suggestions. Just pulled the carburetor out (wanted to wait until had I had some idea on what to do). The real problem is not a bent plate. One of the nuts and bolt for the carburetor plate fell out causing the plate to stick open. Looked bent from the top when I inspected it with a mirror.

I will try and find a bore-a-scope and see if I can see the bolt and nut. Suspect that one of these caused the bad backfire and some of the other problems we had. Strange that the car appeared to run well just before we shut it down due to the high idle. Any suggestion on where a person should go from here?

The engine and carburetor were rebuilt in the USA by a major Porsche rebuilder and they only have 2600 km on them.

Thanks

[pcar9119]

Try useing a magnet in the intake port to see if it will grab the screw. They work pretty good. Just turn the motor by hand to get the intake valve shut so you can get in there. Good luck...

[James Brown]

There is no nut just a screw, if it fell out while runnng most likley it pased through the motor. If you do find it, use red loctite when re-installing. Pelican sells a rebuld kit for Zeniths.

[D911SC]

Originally Posted by James Brown

most likely it passed through

Reminds me of when my son swallowed a coin. No magnets, we just waited until it 'passed through'

[James Brown]

Hopfully this is a little "cleaner"