On Tue, 11 Nov 1997 08:18:27 -0600 Robert Allen <boballen@sky.net>
writes:
>Barney Gaylord wrote:
>
>> I was just reviewing some maintenance records. In September 1990 I
installed a Mallory dual points distributor in my MGA. In July of 1997 I
replaced the contact points for the first time. In between I adjusted
the gap(s) occasionally, maybe once a year. Elapsed distance was a
little over 70,000 miles. One set was pretty well "used up". The other
set didn't look half bad, so I put them in the box with the travel
spares.
>>
>> One for the records? Seems like a long life to me.
>
>What record would that be Barney? For being a cheap-ass?
OK, smart-ass. I'll take a shot at answering all your questions in turn,
starting with this one. You be damn right I'm cheap. That's what these
cars are all about isn't it? Like 19,000 miles on $300 worth of
maintenance, including commercial oil changes. This MGA ain't no Ferrari
(thank God). And in case you missed the update, I made a little mistake
in the mileage. It was 90,000 miles, not 70,000.
>Or the anal attentiveness award for actually having records that old
just for a car?
This anal attentive attitude for keeping records and receipts can pay
off. I've saved hundreds of dollars on warrantee replacements for
mufflers, brake shoes, shock absorbers, and even once the labor and
materials on valve guides. The records also keep track of where the good
deals on parts came from.
>That your filing system is so good you can actually go back and find
stuff?
Depend on it. A suitcase full of receipts isn't worth a dime if you
can't find the one you need when you need it.
>Seriously, tho, I'm imprssed. So wada ya think the secret is?
Maybe Mallory had a better idea? It impresses me as being a very robust
mechanism. One thing I know for sure. If all the mechanical parts in
any dizzy are worn out, the points will have a short life. It helps a
lot to have all new parts in there to start with. When the original
Lucas dizzy got old and really sloppy it was eating a set of points every
10,000 miles.
>Ain't there something upstream of the dizzy that controls the lifespan
of the points?
I don't think so. Just the coil.
>Or maybe Mallory has a really good vendor for condensors?
Couldn't say who the manufacturer is. But it does have the appearance of
good quality. Cadmium plated (gold color) for corrosion resistance, and
heavy glossy potting compound around the wire end. It mounts on the
outside of the Mallory dizzy, and I think it's a bit larger than the one
that goes inside of the Lucas dizzy. Could be a little higher
capacitance.
>What coil or you running? Big ballast resistor and low voltage to the
points?
Lucas 40,000 volt sport coil, no ballast resistor, and full voltage. The
coil is a little lower resistance than the original coil, so it also runs
more current through the points.
>Or maybe the load on the primary side of the ignition is lessoned the
higher the revs? I think current requirements for points-type ignitions
lessen the higher the RPM. I don't figure you've spent a heck of a lot of
those 90,000 miles in stop-and-go traffic.
The dwell is fairly constant regardless of engine speed, so the points
are spending the same total amount of time (per minute) closed and
drawing current. That's one of the advantages of the dual points setup,
keeping the contacts closed long enough at higher speeds so the dwell
doesn't change.
>I don't see how anything on the secondary side of the system makes any
difference on points longevity.
A good capacitor helps for sure. It may also have something to do with
the fact that these points open (break) a little quicker than the
standard Lucas setup, and that may reduce arcing.
>Say! How many times did that Mallory strand you beside the road because
the "little black box" worked perfect right up the point of going hooters
high?
No little black box here, and no resistor either, just the coil and the
points. This dizzy has never failed me. And as best I can tell by close
inspection, it appears to be in extremely good condition after running
90,000 miles. The mechanical advance mechanism and the shaft bushing are
good as new.
Incidentally, I still haven't changed the cap, rotor, or condenser. It
runs great and never misses a beat, so why waste the money? Call me
tight if you want. I just squeak when I walk, that's all.
Barney Gaylord
1958 MGA with an attitude
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