H4 carbs Float cap.

arcturus · Dec 30th, 2018, 14:40

Hi, anybody know what the purpose of the "caps" under the float lids attachment bolt are? also the alu' washer with the dimples?

blueosprey90 · Dec 30th, 2018, 22:29

This is only a guess, but I think they might allow air into the float bowl.

On the MGA SU-4s and on my SU-6s, there is an overflow tube with vented washers that have a dual purpose.

One purpose is to allow air into the float bowl. This prevent a vacuum which would in turn prevent fuel from flowing into the carb body.

The second purpose is to route fuel away from the manifold in case the float chamber overflows due to a failure of the needle and seat valve or alternatively, Grose Jet, that regulates the flow of fuel into the float chamber.

I suppose my question is whether fuel will leak out of the float chamber through the Volvo SU-4 cap assembly. If so, not so good with the hot manifold directly underneath.

Dec 30th, 2018, 22:29	#2
blueosprey90 Master Member Last Online: Yesterday 22:18 Join Date: May 2017 Location: New Milford, Connecticut	This is only a guess, but I think they might allow air into the float bowl. On the MGA SU-4s and on my SU-6s, there is an overflow tube with vented washers that have a dual purpose. One purpose is to allow air into the float bowl. This prevent a vacuum which would in turn prevent fuel from flowing into the carb body. The second purpose is to route fuel away from the manifold in case the float chamber overflows due to a failure of the needle and seat valve or alternatively, Grose Jet, that regulates the flow of fuel into the float chamber. I suppose my question is whether fuel will leak out of the float chamber through the Volvo SU-4 cap assembly. If so, not so good with the hot manifold directly underneath.

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