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MG Midget and Sprite Technical - strange manifold mod.

Seems to have two tapping points on the block side of the inlet manifold. Anybody any idea what they're for ?

http://www.ebay.co.uk/itm/TWIN-CARB-INLET-MANIFOLD-MG-MIDGET-SPRITE-COOPER-CLASSIC-MINI-A-SERIES-/272443785629?hash=item3f6eea419d:g:RW4AAOSwKOJYI05x
M J Chapman

My guess is either vacuum gauge or dizzy vacuum advance
Doug Plumb

Brake servo?
Guy Weller

Doug and Guy,I think for any of those applications you'd only need one central tapping - why two?
M J Chapman

Nitrous oxide?
Dave O'Neill 2

OK Mr Chapman,
How about, . . .
one for a servo and one for a vacuum gauge. That would make two wouldn't it? ;-}
Guy Weller

Guy, are you looking at the right ports? They are near the manifold face - pictures 2 & 3.
Dave O'Neill 2

Probably not then, on my phone there is only one photo with a view from the carb side and a series of plugged tappings along the top of the bridge pipe. Isn't that what we are talking about?
Manifold looks expensive at £90 !
Guy Weller

It is very expensive, but it has been "adapted for racing", apparently!

The seller also claims it is for Sprite and Midget, but will also fit Minis, but Spridget and Mini manifolds are markedly different.
Dave O'Neill 2

Probably for a manometer setup

Fergus

The manifold is of a type located to the head by locating rings. The head has been attached to a head that does not have the counterbore to accept the rings so it has been drilled to locate the manifold in position on the head by using roll pins. The head that it was used on will have corresponding holes.
Alan
Alan Anstead

So its been "adapted for racing" and as Alan says modded to fit a head without locating rings, but surely someone forgot to open out the inlet port to eliminate the step?

What sort of racing would that be?

Rob
Rob aka MG Moneypit

The ports in question were the ones on top of the runners, I believe.

Dave O'Neill 2

Further observations - the tapping/port on the left is threaded (and who knows, it may be 9/32 BSF !)while the one on the right has tube-grip ferrules.Is this difference significant, or is just what was a available at the time? The CSK heads,I guess are blanking studs. So it looks like a toss-up between the manometer theory and the nitrous oxide injection theory.
.........unless you know differently - come in Prop!
M J Chapman

I don't like the manometer theory. In that position, and due to the cross tube, I don't think you could use a manometer and get anything useable from it. Nitro injection is my bet.

Rob
Rob aka MG Moneypit

What about water injection? A mate mentioned trying it some years ago at a Castle Combe track day and he said it seemed to pull better on the straights.
David Billington

This thread was discussed between 11/11/2016 and 13/11/2016

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