Gipsy manifold material

[David KParticipant @davidk77137]

According to my plans the inlet manifold should be made of mild steel.

looking at a couple of completed engines on the internet I notice one has used brass and another has used a mixture of brass and steel as the one pictured below.

Is there any reason for using brass , as in the bottom plate on this one,

[David KParticipant @davidk77137]

[old martParticipant @oldmart]

It looks pretty.

[JasonBModerator @jasonb]

And it does not show the silver solder joint

[SteviegtrParticipant @steviegtr]

WOW. Very nice.

[David KParticipant @davidk77137]

Stainless it is then.

[JasonBModerator @jasonb]

I think if I were doing it I would machine some stock down to 0.475" and then mill out the recess from below to 0.425" deep and then recess the bottom plate into the 3/8" wide passage so no joints are visible unless you are looking from underneath.

[Anonymous]

Depends on which engine, but on the Gipsy Major the inlet manifold was steel. It has two half pressings with a welded seam and individual steel plates welded on that bolted to the cylinder heads.

Andrew

[Tim StevensParticipant @timstevens64731]

Brass has an expansion coefficient very close to that for Al alloys. The value for Steel is rather less. I suspect this might have been one factor in the mind of the bloke what made it.

Cheers, Tim

[Paul KempParticipant @paulkemp46892]

Posted by Tim Stevens on 20/01/2020 18:19:24:

Brass has an expansion coefficient very close to that for Al alloys. The value for Steel is rather less. I suspect this might have been one factor in the mind of the bloke what made it.

Cheers, Tim

Not sure I follow your thinking there? Steel top, brass bottom, sounds like a recipe for a banana to me? As it's the inlet manifold would it actually get hot enough over its length to make any appreciable difference? If it were the exhaust a different story maybe. If you are suggesting coef of ex to match the aluminium crankcase then that only holds good if the whole thing is brass?

Paul.

[JasonBModerator @jasonb]

The lower tapered part down to the carb is aluminium but at such a small size I doubt expansion would be an issue and the suggested Araldite to join it would have enough flex to compensate.

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