At 12:11 PM 4/5/95 -0400, RDelany999@aol.com wrote:
>I'm new to the list, have a '74 MGB chrome bumper, and close to closing on a
>'53 TD. I live in Bucks County, PA
>
>Iwould like to know if anyone has experience with changing the coil
>to a high performance (40,000V) one. Does it make a difference?
That's not an electrical question, it's an ignition question. An
electrical question on these cars means something like, "When I
turn the lights on, the car makes this funny gurgling noise from
behind the driver's seat. What's going on?"
>What are the negatives associated with increasing the voltage?
>I am gettting the MGB ready for the road (Spring fever) and am thinking of
>changing the coil if it really does make a difference.
A hot coil makes the car start and ignite a little better. You won't
realize much performance gain unless you make other modifications.
For instance, if you run very rich trying to get maximum power, a
hot coil can help ignite the mixture. Also it's a plus at very high
RPM, which shouldn't be an issue with a stock '74 and its single
valve springs.
You should have no negatives; I've run the Lucas Sport and Lucas
Super coils in my cars for years. I have been led to understand that
running a fully electronic ignition, on the other hand, can make a
significant difference, especially if you go with a multiple-spark
setup. Of course, no matter what the triggering mechanism, your
timing won't be steady if the distributor body is worn, and the
distributor won't be steady if the cam gear and drive dog is sloppy,
and, and, and that way lies shipwright's disease.
Speaking of distributors, around 1975 M.G. went over to the Lucas
45D4 distributor, replacing the 25D4 that had been around since the
first cars that Fred Flintstone didn't have to push with his feet.
The old ones were held in place by a clamping plate that tightens
down on a ring of pot-metal cast into the bottom of the distributor,
like a section of pipe that sticks down toward the block. After 20
years or so of half-stoned troglodytes whanging on the motor at
the gas station to try to get the thing to pass smog, the ring often
develops stress cracks and can even lose pieces of its circumference
altogether. When this happens, the typical failure is that first, the
distributor loses its timing regularly and has to be set several times
a day, usually accompanied by additional tightening of the clamping
plate on the distributor so it will stay put. This eventually snaps
the ring of pot-metal completely, causing the distributor to jump
out of the engine block at 7000 RPM on the section of Sears Point
between turn 2 and turn 3; the unburned gas ignites in the center
section of the exhaust with a huge BANG that convinces you that
you've just littered the countryside with the festering remains of
the corpse of Mowog, and you wonder why there's no gory black
smear behind you as you pull off course and climb out of the car
to walk back to the paddock. Only later, as you cannibalize the
plug wires off the race car to keep your VW GTI running so you
can get to work to pay off your credit cards, will you discover that
the distributor is merely resting loose on top of the block. This
will lead you to buy a 45D4 distributor, install the motor in your
street MGB, and eventually blow a big hole in the #4 piston as
you accelerate away from a BMW M5 in second gear in an
impromptu contest of speed at the railroad crossing near Central
Expressway.
And my coworkers wonder why I put up with these cars...
--
Scott Fisher
fisher@avistar.com SEFisher@AOL.com
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