Author Topic: ROSEBERRY MOFFAT INLET/EXHAUST MANIFOLDS, THEY ARE NOT ALL THE SAME  (Read 2975 times)

*hatman*

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A while ago when I was pulling down my Moffat Virtue 4HP for restoration I noticed with great interest various numbers and maker marks that were cast or stamped in various parts of the block and other parts such as the inlet/exhaust manifold.

Upon cleaning the mating face of the manifold (the face that has the gasket to it) I noted and photographed a distinct stamp which read 4V. The manifold exhaust thread was flogged out so on finding a good replacement I had a look and found a similar stamp on the clean face, which to the casual glance would not have been noticed or ignored. It was stamped very faintly 3V, not 4V.

Do not ignore these marks. I was all ready to fire up the Moffat and discovered through casual conversation with Don Reid, who knows Roseberry's backwards blindfolded that I would have had problems with it running. Why? Well the manifolds all look identical from the outside but each engine that had this manifold (3, 4 and 6HP) had a manifold with a different internal Venturi flow setup. Long story short, the 3HP engine had a 3V stamped manifold and had a narrower flow internally so if you try and use these on the larger engines then you will have some issues apparently running the engine properly. Same goes for using a 4V on a 6HP. Maybe everyone knows this already but if not now you have learned one thing today to keep people in awe of your "how the hell do you kow that"
knowledge. :)

cobbadog

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Re: ROSEBERRY MOFFAT INLET/EXHAUST MANIFOLDS, THEY ARE NOT ALL THE SAME
« Reply #1 on: 08 April, 2012, 04:23:33 pm »
Very interesting, I now wonder if you could run them the other way around ie, a 6v manifold on a 4hp and so on.
Cheers, John & Dee. Coopernook. NSW.

*hatman*

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Re: ROSEBERRY MOFFAT INLET/EXHAUST MANIFOLDS, THEY ARE NOT ALL THE SAME
« Reply #2 on: 08 April, 2012, 11:25:00 pm »
Actually, the 6HP is different again as I have found out.