carb issue ?

[Dick Weiss]

Using a file won't get a flat reference in the beginning and a match to its neighboring surface; After I use a flat lapping plate w/fine emory cloth,
I resurface the carb's top followed by machining the "feet" on a mill (Unimat machine), and finally on the lapping plate; I don't have a larger mill.

[anthony magsanay]

Hello, all, it's been two weeks since I sought advice and guidance concerning my 64's carb issue. After much consternation and two visits to two different shops it remained unresolved. Thanks to the members that took the time to advise me. It turns out it was the gasket between the manifold and the head that went bad. I am completely indebted to you all. I owe you a cold one. I will be at Rennsport this week in my Porsche Hawaii tee shirt, if you see me tap me on the shoulder and say "Hey , Keith where's that beer ? Again , thanks to all

[Wes Bender]

Thanks for reporting back on the cause. All too often there's a request for advice or assistance, but we never find out what actually fixed the problem.

[Dick Weiss]

Thankfully, the manifold faces don't get warped--being aluminum; Unusual for the gasket between the manifold
and the port face(s) failed, but age will happen.

[Max Handley]

A good piece of window glass & wer/dry sand paper , start with 400 end with 1000 & 1500.use soapy water.

[Ron LaDow]

There is no reason to work Zenith airhorns gasket surface any better than you can get from a disc- or belt-sander, 80-grit or so. The gasket is never under pressure and also never even 'sees' liquid fuel, except as it is splashed to the joint under cornering. Or if you really screwed up on the float level.
Look at the float level; make sure that is right. Flatten the top of the float bowl and cover with the coarsest file you have, use the thinnest gasket you can find, and spend your efforts where it matters. The top gasket mating surfaces ain't one of them.
Added by edit:
Harry really did help the preservation of 356s, but his focus on .01mm flatness of Zenith gasket surfaces was not one of his better efforts...

[Martin Benade]

Ron, I agree except for 80# paper on a power tool. In the wrong hands you could be missing 3mm of pot metal in a flash, and it's not coming back. 80# on a piece of glass or even plywood would be safe though.

[Dick Weiss]

As mentioned earlier w/un-stressing Solex carb "feet", I do the same w/the Zenith carb body and top cover to minimize thinning of the surfaces for the proper cover gasket; Original gasket is light tan w/the mfg. name, but the black one can be thin or thick material w/o markings. I finalize the surfaces w/120 and 180 grit emory cloth on a surface lapping plate. (or quartz block)

[Ron LaDow]

Martin,
Dunno the actual alloy, but it's Zn + probably a couple of things. It really doesn't yield quickly to abrasives; tends to 'fill' the abrasive pretty quickly and reducing its cutting ability. But you're right about care; you do need to keep a firm grip on it, as the 'gummed up' abrasive will try to grab it if you press too hard. A light touch does the job.
Don't bother trying to make it 100% flat; you're removing material and you want to remove as little as possible to keep a gasket seal.
Dick,
I stand by my comment. 'Lapping' those surfaces is a waste of time, accomplishing nothing.