FI Main Control Diaphragm

[Don H.]

I am assembling a 7017375 unit. Does the gasket go above or below the main control diaphragm? I can't find it in any of my books. I assume above but want to be sure. Thanks, Don H.

[Dan H.]

Re: FI Main Control Diaphragm

Goes above the diaphram to seal the vacuum signal. Originals gaskets were marked for the top side due to a sharp edge on the that side that would have cut into the the original silk/rubber diaphrams thin skin. Repro diaphrams are made of rubber now, tougher I guess. Make sure the top cover is totally flat for a good seal.
Dan

[Don H.]

Re: FI Main Control Diaphragm

Thanks Dan, that is what I thought. I have wondered why don't they use a gasket on the enrichment diaphragm? I do surface all housings with a granite surface plate. Recently I found an original gasket in my parts that was marked as you mentioned but it was very old and curled. The new kits are very nice. Thanks again, Don H.

[Clem Z.]

Re: FI Main Control Diaphragm

Thanks Dan, that is what I thought. I have wondered why don't they use a gasket on the enrichment diaphragm? I do surface all housings with a granite surface plate. Recently I found an original gasket in my parts that was marked as you mentioned but it was very old and curled. The new kits are very nice. Thanks again, Don H.

shrunk paper gasket can be brought back to life by soaking them in hot water. i have to do that with older carb kits

[Jim L.]

Re: FI Main Control Diaphragm

I have wondered why don't they use a gasket on the enrichment diaphragm?

A minor leak at the enrichment diaphragm doesn't cause major problems.

The main diaphragm is subject to more subtle vacuum levels than the enrichment diaphragm. As such, a vacuum leak at the main diaphragm would be disruptive so it needs better sealing.

Jim