Zenith Carbs

[ed - 911T]

I'm rebuilding the zenith carbs in a '71 911T… but I discovered something intriguing concerning the little accelerator pump check valves under the injector. I found all three in one carb just lying in the bottom of the float bowl - not where they belong, and in a place where they were clearly put by a previous owner, cause it would be impossible for them to come out of their correct position once the carb was bolted together. (note - I have not yet put the new o-ring on the clean injector in this photo)

Also, in the other carb all three check valves were totally missing - no where to be found ??

Here's my question - how does this valve actually work and why do I need it ? I have been driving this car for 20 years without any - apparent - trouble with throttle response, acceleration, etc. Although maybe if there were a subtle problem I wouldn't know it… which suggests (maybe ?) this valve performs an insignificant function - if any ?

Finally, if it is important to include this valve in the rebuild does anyone know where I can buy just three ? Oh, and I also need one fuel strainer for the banjo fitting.

Thanks for any advice/help.

[unclebilly]

Maybe it prevents siphoning back and improves cold starts...

[LakeCleElum]

Here's how it happens, I've done it:

Most don't realize the check valves are there when they pull the carbs apart. They fall out when the disassembled carb is turned upside down. They get lost, thrown away or end up elsewhere in carb. I found mine on the workbench and it took a few to figure out where they came from.

I may have your parts...Have 3 extra carbs and one is just for spares....PM me a reminder please....Thax......

[Porsche-O-Phile]

Very interested in this - I have a set I'm rebuilding for use on my 2.7...

[Nostril Cheese]

You may want to go a bit oversize on the O-ring for the accelerator pump. I've found that the O-rings in the kit don't really fit right.