[Redtail]

Hi Guys,

It seems I have an intake manifold leak that I am having trouble fixing.

The main symptom I am trying to cure is the engine stalling when coming to a stop. I have a brand new Zenith carb and I have tried raising the float level all the way to the point that it starts to leak fuel with no success.

I have replaced the manifold gaskets with the late 31 style, torqued to 35 ft-lbs from the inside out, tried installing with and without exhaust glands all to no effect. I had the manifolds decked as a unit at a cylinder head shop so I know they are flat, but I still think there is a leak at the rear intake manifold port.

With the engine hot and at a high idle, when I spray brake cleaner around the rear intake manifold port the RPMs drop significantly, then come back to normal when the brake cleaner evaporates.

Any suggestions what to try next? I hear some people use manifold sealant but that doesn't really seem like a long term fix. I don't think the carb is at fault so I will set the float level back to where it was when I got it. I don't have a problem spending $200 for a new intake and exhaust manifold set, but I don't want to just keep throwing parts at the issue without really understanding what is going on.

Thanks,
Zack