In a message dated 5/17/2005 11:15:21 AM Central Standard Time,
tr3driver@comcast.net writes:
> Even after we were certain that the rotor had failed, it was impossible to
> see
> what was wrong with it! There had to be a carbon track through the rotor,
> connecting the brass contact to the distributor shaft, but we all looked and
> could not see it. Since no one in the group had a spare 4-cyl rotor, we
> hacked
> down a 6-cyl rotor. Fixed the underlying problem (plug boot not making good
> contact to the wire) and drove the remaining 800 miles or so home with no
> further problems. (With that car, anyway.)
>
Those pesky electrons are really quite small and it doesn't take much of a
hole for them to leak through. ;-)
Seriously, I have heard that the OE rotors had the brass arm molded in place
but the new aftermarket jobs had the brass arm riveted on and that this rivet
puts the plastic piece under stress and the resulting crack will make a path
for the current to flow without the need of jumping that gap in the spark plug.
But on the other hand I've had reports (well, one actually) where the failed
rotor had the brass arm molded in so perhaps the rivet is just a red herring.
I've also heard of cars that would idle fine but not run under load because a
rotor was failing. This makes sense when you consider that it takes more
voltage to jump the spark plug gap at higher absolute pressures and the
pressure
in the cylinder is rather low at idle compared to under load.
Dave Massey
57 TR3
71 TR6
80 TR8
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