Lotus Elan

Stromberg Head Intake Ports

PostPost by: rickf » Tue May 18, 2004 1:37 pm

I understand that the leading edge of the casting dividing the "Siamesed" intake ports on the Stromberg heads was blunted because it worked better than the sharp edge that was used in the beginning. I just had the carbs off mine and the edge is very sharp. Should it be blunted?
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PostPost by: steveww » Tue May 18, 2004 2:53 pm

It should be a blunt divide. AFAIK these were all done at the foundry. Initial they tried using a razor edge..... When you say sharp is it razor sharp or just a bit pointed? I have never seen a picture or spec for this detail, anyone else got any ideas?
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PostPost by: elan_fan » Tue May 18, 2004 6:45 pm

By Blunt they mean just that, somebody just took a die grinder and flattened the knife edge that forms where the two ports meet. I have the carbs off my car at the moment......do you want a pic?

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PostPost by: rickf » Tue May 18, 2004 7:07 pm

A picture would be great. The edges feel sharp to the touch, but you can touch them without getting cut.
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PostPost by: steveww » Wed May 19, 2004 8:39 am

A picture would be great. Are you going to post it somewhere or just mail to those that request one?
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PostPost by: DrEntropy » Wed May 19, 2004 12:31 pm

The Stromberg head I have looks as if it has not been heavily treated with a grinder, as it still has the casting swarf at the division. It is a "sharp-ish" edge (i.e. not knife-edge sharp, but not "blunted") with what appears to be a few spots where it had excess casting bits removed.

I can attempt a photo posting here if it would be of help/interest.

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PostPost by: fasterbyelan » Fri May 21, 2004 11:17 am

Miles Wilken's Twin Cam book details the work carried out by Lotus to convert the head to Stromberg carbs. Included are a photo and diagram of the detail you are looking for.

Hope this helps.

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PostPost by: rickf » Fri May 21, 2004 1:10 pm

That drawing is what got me wondering about it. It doesn't seem to call out any radius for that edge though. Mine seems to be as cast and not what I'd call a blunt edge.
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PostPost by: fasterbyelan » Fri May 21, 2004 1:31 pm

I imagine Lotus would have relied on the cast finish. Wheather there are improvements to be gained by hand finishing I'm not sure - there probably is but the results did not justify the extra labour costs. And one should not forget the Elan was (and still is) a very fast car for the road in its 'as built' form !

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PostPost by: steveww » Fri May 21, 2004 1:40 pm

Like most heads a bit of time spent with the dremell and some knowledge flow improvements can be made. You need to lift the head off and take out all the valves etc. A lot of work for may be 1-2bhp???
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