I believe that have been nicely insulted and chastised for asking
such a question. One would think that I just asked a Porsche
owner if he would like a ride in my Ferrari! Fortunately for me,
I am not really bothered by personal attacks or by being called
ignorant. I am a physicist by training and by occupation. Living
in Tulsa, scientists are frequently attacked for asking questions.
I wrote,
> > How would YOU jet these carbs to optimize performance
> > in the 4k to 5.5k rpm range on this or your MG engine?
Bill replied,
> This is a totally meaningless question and anyone that tries to
> answer it will be offering information with zero value.
I am asking for a starting point, not the final solution.
> It is IMPOSSIBLE to compare two engines of different type,
> displacement, and specification.
Bull. Yes they are different but air-flow dynamics is air flow
dynamics. I was hoping for insight by people who have studied
more than just the MG head.
> BTW - you did know that unless you have a non-stock alloy
> head, the MGB only uses ONE carb, not TWO, didn't you?
Yes, I have a little experience with twinned-port heads on the
MG and with cross flow heads on the BMWs. Also, isn't it only
the late model MGBs that use only one Z-S carb? My '70 B-GT
used two SUs -- with a balance-tube manifold but still into twinned
ports.
> First, go buy a Weber book and find out what the settings for a
> BMW engine of your state of tune might be (you don't bother
> offering cam information). That is only a very basic guide to what
> size venturis and what other settings you may want to try. Then
> have an expert do the tuning.
All good advice. I have the Weber books and I have studied
them. I am NOT experienced with tuning these carbs. I read that
you were offended that I didn't offer cam specifications. Again,
I am looking for a starting place, not the final solution. The cam is
a stock 1968 BMW 1600 engine cam. Is the problem here the
cam or is it the letters "B", "M" and "W"?
> I take it that you are not such an expert from your question,
Rhetoric is always subject to interpretation.
> ...as well as your suggestion that a 45 DCOE must be too large
> for the 1600. It is not the carb size so much as the venturi size
> that governs behaviour - I have one set of 40 DCOE with larger
> main venturis than another set of 45 DCOE I use on a different
> engine.
Application notes recommend the 40DCOE for this BMW
engine. I have 45DCOEs and I haven't owned them long enough
or asked enough nice people questions to know the difference.
> Please believe me - if you have no specialised knowledge,
> Webers are NOT the carbs to start trying to tune by guess, and
> by misinformation.
Perhaps I should have then asked friendly list members for help?
> Bill
> (10 Webers currently in use)
Happy Wednesday!
Rick
(4 DCNF Webers currently in use, 2 DCOEs just purchased --
since we're keeping score)
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