[TR] TR6 Problem, TR4

Randall tr3driver at ca.rr.com
Tue Sep 4 17:55:58 MDT 2007


>  I suppose I  should change the fuel 
> filter since it 
> appears that little rubber silvers are  getting by which 
> caused the fuel shut off 

Another possibility is that the soft lines between the filter & the carbs
are starting to deteriorate & shed.  I've had that happen several times with
soft lines that appear fine at first, but on closer examination show tiny
cracks, especially when they are flexed.  The (original ?) cloth-covered
ones are worst, since you cannot easily see the condition of the rubber.  In
that case, take one off and look at the end where the rubber is exposed
between the cloth and the bore.  If you see any cracks, it's ready to be
replaced.

> I bet I have had a 
> half dozen rotors go south 
> on me during that  time.  What's up wit that? 

The original design may actually have been just a tad weak in this area.  If
you approximate the distance through the middle of the rotor, from the
contact arm to the center post of the distributor, I think it turns out to
be the shortest route to ground found anywhere in the high tension system
except for the actual plug tips.  The other cars I've owned have been
arranged to make this distance much larger.

IMO the popularity of Lucas Sports coils and other ignition "upgrades" just
aggravates the problem.  Even the stock coil & points is capable of
generating more voltage than it takes to jump the combined plug gap and
rotor/cap gap; so effectively those two gaps limit system voltage no matter
how much the coil is capable of.  But, if there is a problem with the plug
or plug wire; or if you run wider than stock plug gaps either intentionally
or by not resetting the gaps as often, then the voltage rises until it is
either limited by the coil/points capability or goes to ground somewhere
else.   If it jumps the path through the rotor to the dizzy shaft, then it
will damage the plastic of the rotor, leaving a "carbon track" that will
conduct easier next time.  Eventually it becomes the easiest path to ground
all the time, and the engine will no longer run at all.

Another problem seems to be that many modern replacement rotors are made of
lower quality plastic than the originals were.

Randall


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