At 02:23 PM 12/7/03 -0500, Richard Taylor wrote:
>OK Jack,
>
>Since you now seem be the target of choice for carburetor/manifold queries,
>permit me to pose one more.
Uh-oh. I smell trouble here.
>As you know my racing M.O. has always been subject to a certain amount of,
>well let's say, unconventional motivation. Art-form, discomfort, and
>self-induced complexity seem to have all crept into my program.
Your approach looks like a lot of fun, but I've always wondered if you'd do
the same thing under different medication.
> With respect
>to carburetion, 6 years ago I bought a pair of 2" SUs. They were clean and
>shiny and cost only $100. More importantly, I liked the authoritative scale
>of them on the engine rather than those ugly little Strombergs (which always
>started easier and ran flawlessly).
>
>My cam and compression ratio are relatively mild and the motor makes only
>125 hp @ 5500 rpms (and that's my shift point).
>
>So here's my question: what would you speculate I give up in hp and torque
>because of my compromise in carburetion?
In keeping with my policy of trying to keep genuine data separate from
opinion, I've got to say "I don't know". If it works for you and you like
it for whatever reason, I think you should leave it alone. I certainly
agree that SU domes are prettier than those short, fat Strom domes.
>My argument for using the larger bore is that the piston will only rise to
>whatever level it requires to suck in the air it needs. That is to say if
>the cfm is satisfied with the piston open 80% of the way then everything is
>copasetic. You buy that?
Well, partly. the piston rises as a result of the vacuum created at the
bridge and that is mostly a result of the velocity of air across the
bridge. A larger diameter throat will give a lower velocity, hence the
piston will be lower as you have surmised. I think that since the needle
will not be out of the jet tube as far, the mixture will be leaner, and you
should experiment with needles that are richer in the rpm range where you race.
>Now don't laugh at my ignorance. I wouldn't laugh at you if you didn't know
>what the magnetic compass does at 7000 ft directly above the magnetic North
>Pole, inverted and at positive G's, would I?
Hey, I already know the answer to that one. Some guy named Richard Taylor
told me once.
>Richard Taylor
>
>TR-4
>
>Atlanta
uncle jack
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