QUOTE(Midtowner @ Feb 9 2009, 03:29 PM)
QUOTE(Phoenix 914-6GT @ Feb 8 2009, 09:55 PM)
Points? If you have a pertronics this isn't a good idea. I just unhooked one of the fuel lines after the pump and turned on the pump. Works great and gets most of the gas out of the tank.
I have a Pertronics and getting ready to drain the tank. Why is this a bad idea?
Inside the distributor there are points or an electronic ignition circuit like the
pertronix that act like "points". Each will close (short) the coil lead to ground
as the distributor rotates.
The points are mechanical and the electronic devices use an electronic trigger.
In the case of the pertronix, they use a magnet.
When the sensor "sees" the magnet, it connects the coil lead to ground.
The problem for devices like the pertronix is the combination of their design
and unlucky engine rotational position when not running.
The early pertronix design (I believe this was fixed in the Pertronix II)
grounds the coil lead while the magnet is "seen" rather then just
a brief amount of time only when magnet is first seen.
When the engine stops, it might stop at a point that the distributor is positioned
such that the sensor is directly over the trigger point.
On a pertronix, this means that it continuously sees the magnet and
is stuck grounding the coil. The full coil current is
being handled by the module. The module cannot handle this much
continuous current for extended periods of time. It overheats and kills it.
This is why people warn about leaving the ignition on burns up
pertronix. It actually depends on where the engine stops.
BTW, this same issue exists for points, other than points don't burn up.
However, even with points it is possible that a coil could get very hot.
--- bill