Concerning my 1967 TR-4A IRS...
I'm plagued with a continuing miss which begins at 2500-3000 rpm, and makes
the car practically undrivable on the highway. I've replaced points, rotor
condensor, plugs, wires, coil, distributor base plate, and springs on
the centrifugal advance/retard system. I've sealed the leaking vacuum
advance diaphram as recommended by another reader (which seemed to work),
but my miss continues. The points don't last long (the coil sees 12 V, there
is no balast resistor). I installed a hotter coil (Accel) which helped some.
I've
opened the plug gaps a bit, but that doesn't seem to help. I've replaced
the needles and jets and rebuilt the carbs--I think they are set up properly.
I rebuilt the fuel pump.
It does smoke a bit, but the plugs will last six months or so before becoming
so fouled that they are a problem. (but I will try a new set just to rule them
out--the problem was much less when they were new.)
The only symptom that gives me a clue is the variation in the timing; I can
see the timing mark swing about under the strobe. From a nominal position
(about 0.75 to 1.0 inch on the circumference of the flywheeel pulley before
top dead center) the mark will move around almost to the TDC mark. I believe
that this fluctuation is caused by some "jerkiness" or friction in either
the centrifugal or vacuum advance system, but maybe there is another cause.
There is no significant slop in the distributor bushing, as far as I can tell.
Another strange clue...the rotor has a dark smudge indicating (to me) that
the spark is jumping from one corner of the rotor; I would expect this
smudge to be more central on the arc-shaped brass rotor surface.
_______ * smudge here, I think
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Top View of Rotor (imagination required!)
(drawn from memory, and I don't have much of that anymore!)
I'm trying to figure out how it may be that the rotor doesn't align
with one of the plug wire terminals when the points open; even if the timing
is right...I have made everything correct, I think, except that I haven't
removed the gear sits on the cam shaft to drive the distributor. If this
is off one tooth, would it cause my problem?
I'll welcome any advice or ideas. I'm about ready to chuck the distributor
and install a Mallory (or just install electronic ignition, but if the problem
is in the base plate or advance system, I haven't solved anything this way)
Anybody got a Mallory distributor for sale cheap?
Thanks,
Ray
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Ray W. James, P.E., Ph.D.
Civil Engineering Department
Texas A&M University
College Station, TX 77843
Phone (409)845-7436; Fax (409)845-3410
E-mail: r-james@tamu.edu
Date: 09/24/1999 Time: 3:38:31 PM
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