View single post by Mark Rosenbaum
 Posted: 06-11-2005 09:48 pm
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Mark Rosenbaum



Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
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 I did some research early last year which sheds a bit of light on this.  First of all, as far as I have been able to document, all JHs used the same head casting, A907E0311Y, which would have had the smaller ports.  As far as I've been able to discover, the B907... head was never put into production.  The C907... head was introduced sometime between engine number 12020 and engine number 14302 as reported by 'Overdrive Gear' above.  (FWIW, each 9xx engine had its serial number stamped on the head, block and bearing saddle.)

A point which may be of particular interest to those racing their JHs is that two versions of the Stromberg intake manifold were used.  The earlier version, which has no casting number but which apparently is A907... or B907E0250Y, has small ports measuring about  1.688" wide and 1" high.  Manifold C907... appears to have been introduced fairly early, perhaps even before the changeover to the later block, and has larger ports measuring about 1.875" wide and 1" high.  I'd expect that the significantly larger port area of the later manifold would give a noticeable increase in torque throughout the rpm range.  The C907... manifold was used, with minor machining differences, on both the JH and Lotus cars with Strombergs, and thus ought to be readily available.

 

Attachment: Stromberg Manifold identification.jpg (Downloaded 59 times)

Last edited on 06-11-2005 09:54 pm by Mark Rosenbaum