Carb balancing

[tparker]

I have a 64 356c with twin Zenith carbs(?) Has anyone ever used one of those "snail" twin carb syncronisers and if so are they suitable? I think the carbs on my car are way out of adjustment but need to get them balanced first. Short of using a piece of tubing and listening to each one, does anyone have a procedure for doing this?

Thanks,

Tony

[Gary71]

Hi Tony,

I've used one on my 911 with Zeniths and it works fine. I'd imagine the setup on the 356 is similar, just make sure the diameter of the syncrometer inlet you buy is suitable for your carbs.

Not certain how many chokes each of your carbs has but I'll assume two each.

Disconnect cross linkage
Wind airbypass screws all the way in
Set the mixture screws to the same setting from fully wound in. No idea how many turns on a 356 but the 911 is 2.5
Match flow rates at a slightly raised idle speed using the idle stop screw on each carb. Measure flow on the rearmost two chokes.
Compare flow rates across each choke on one carb and open the air bypass on the cylinder flowing the least until it matches. You'll find the idle speed goes up whilst your're doing this...
Repeat on the other carb, then reset the idle speed by balancing the two carbs to each other again on the rearmost choke, the front two should now be matched to the rear via the air bypass.
Adjust all the mixture control screws until the engine runs smoothest. This sounds very vague (and it is! ) but when you hit the sweet spot on the mixture its very obvious.

You may have to go through the loop a few times to gradually settle everything. Once each choke is matched and the idle speed is correct then reconnect the linkage ensuring no preload across the carbs.

Hope this works, I'll delete my advice once a 356 expert pronounces it as rubbish!

[tparker]

Gary,

thanks for your reply - I am sure that your procedure is going to do the trick.

One question though (and this may be a dumb one) is that looking at the carb, I am presuming that the syncroniser fits into where the air cleaner fits onto. There are two adjustment screws, one for each throat and my question is how does the syncroniser measure the air flow to each separate one?

If this is a dumb question I apologise but whilst I can see how the adjustments can be made, I guess I don't understand how to use the tool.

Cheers again,

Tony

[Gary71]

The balancer normally locates into the trumpets above each choke, post a picture so we can take look.