>>>>> On Tue, 19 May 1992 15:11 PDT, Dennis Wilson <DWILSON@OREGON.UOREGON.EDU>
>said:
Dennis> X-Envelope-To: british-cars@hoosier.utah.edu
Dennis> X-Vms-To: IN%"british-cars@hoosier.utah.edu"
Dennis> At the moment I have one of the netters staying with me. he
Dennis> is from Los Crusos or something in New Mexico. We were
Dennis> talking last night and we wondered why the car tends to
Dennis> backfire (or sound as if it does) when you remove the the
Dennis> muffler, wind up the revs then coast so the engine decelerates
Dennis> the car.
I'm not entirely sure, but I'm pretty convinced it has to do with the
advance of the distributor. With the throttle closed you develop
quite a vacuum in the intake manifold which retards (I think) the
spark a lot. It may get retarded so far that the sparking-plug fires
while the exhaust valve is closing. Crackle-crackle-crackle!
This pretty much went away on Sybil when her distributor got rebuilt,
so the ("previously frozen") centrifugal advance weights could
compensate for the effect.
--berry
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