View single post by Mark Rosenbaum
 Posted: 10-25-2005 03:57 pm
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Mark Rosenbaum



Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
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 All JHs, and early Lotus cars with the 907 engine, originally came with the A907E0311Y head casting.  At some time after the JH ceased production, Lotus changed the casting to the C907... version.  This occurred somewhere after engine S/N 12009 and before engine S/N 14302, but I don't know exactly when.

It's my understanding that the C907... head has larger ports with an improved shape for better gas flow.  Presumably at around the same time, the intake manifold used with Stromberg carbs was changed to accomodate these larger ports.  I would suppose that a similar change would have been made to the intake manifold used with Dellorto carbs.

If your question involves an actual cylinder head, I'd be interested in knowing all of the numbers stamped or cast into it -- not only the serial number and casting number, but any numbers to be found on the intake and exhaust manifold faces, head gasket face, or elsewhere.