[TR] Ballasted or un-ballasted coil in a 74 TR6

[Randall]

> I am 
> thinking about trying the Pertronix Flame Thrower coil, but 
> am unsure if I need the ballasted or un-ballasted. 

For a 74 TR6, normally you would want the "external ballast required" "1.5
ohm" coil.  Pertronix P/N 40001, 40011 or 40111.

However, especially if you are having ignition problems, I would suggest
double-checking your ballast resistance first.  Turn the engine until the
points are closed, turn the key on, and check the voltage from the coil
positive to ground.  If you find nearly 12v here, someone has bypassed the
ballast resistance that would normally be incorporated in the wiring
harness.  If you find less than 6v, either the coil is shorted or the
ballast resistance in the harness is too high (possibly a bad connection or
the wire is corroded).

While it's not impossible, the coil is one of the last things I would
suspect for a problem that only shows at idle.  Relatively low rpm combined
with relatively low cylinder pressures mean that even a coil that is totally
inadequate under other conditions would work fine at idle.

Randall