Tach eats Pertronix

[eclair]

OK OK, it seems the only explanation. Installed Pertronix system less than 100 miles ago. Coincidentally, though the car ran well, the tach seemed to cease to work at that time. Now the car will not start. The coil works but the tach wire to coil +side was reading 6 volts until I disengaged same. What is going on. Did a malfunctioning tach damage the pertronix?


Gentlemen,
Thank you ed, Gary, Richard ,Brian et alia for responding to my question re: my pert vs. tach situation. No, I never leave the key in the "on" position -learned that from the old points days. But think I've fried my Pertronix unit. Will have the Smith's tach rebuilt (Nisonger Instrument of New York) before trying again with new ignitor/flamethrower (before going over to ed's side with points/cond.).
Tom
Havre de Grace, Maryland USA
.

[twincamman]

Leaving the ignition on and not cranking the motor destroys the Pertonics system it appears ..ed

[archigator]

Leaving the ignition on and not cranking the motor destroys the Pertonics system it appears ..ed

Unfortunately, it warns about this in the literature that comes with the Flame Thrower coil...

Gary
'71 Sprint FHC
Miami, Florida

[twincamman]

really --POINTS AND CONDENSER -for these cars and forget the space age junk ---ed

[ricarbo]

As the standard tacho only has a 'loop through' connection of the ignition supply wire, it just can't be responsible for this failure. Whether or not the tacho will work is another question, since you have changed the characteristics of the current flowing down the supply cable. Usual remedy for that is to swap the internal circuit of the tacho to 'voltage sensing' instead of 'current sensing', which has the bonus of requiring recalibration, so you can be more confident it tells the truth. It's not unreasonable for the original circuit to be out of whack after all these years.
Richard

[alfert]

I believe the ign can not be left in the on position without the car running for more then three 3 minutes or you will burn the control unit in the diet. Hard to believe, but true.
Brian

[billwill]

You can burn out a coil on the original system too; if the engine stops with the points closed and you leave the ignition on.

[elancoupe]

This also applies to the photocell ignitions like Lumenition and Piranha/Newtronics.

[MyLotus]

Had the exact same experience: Pertronix and tach will work for a while and then ignition is gone. I disconnected the white wire from the tach to the ignition coil + and ran a wire directly from the fuse box to the coil +. Engine runs normally but no tach. It seems that there is no other option than to convert the tach or go back to points.