Mallory HyFire and heat

[jwinkler]

Any idea if the HyFire ignition box is very heat sensitive? It's failing on me intermittently now, after I opened valve that lets water go to the heater core (I had been keeping it closed, and lately I've left it open). The hose that takes water to and from the heater core runs right over the hyfire, and the ignition dies (most of the time) about 10 minutes into a drive. When I install the ignition bypass plug, the car runs again.

On the other hand, the hyfire is mounted right by the side vent in the engine bay, and I would have guessed that if heat were a problem, the heat from the headers would have caused a problem long ago (I've had the system in the car for a couple of years, and unfortunately, only about 2000 miles).

All comments, suggestions, and experience with the Mallory unit appreciated.

Thanks,

JLW

[Rick Parker]

If the intermitant ignition problem is only occuring when the heater is functioning as you have stated, it would appear that you have isolated the problem causing its failure. Heat sink has always been a problem with transistorized circutry. All parts expand when heated and it sounds like you are experiencing an open circut caused by it. The potting inside could have deteriorated over time and is being affected by vibration or the heat itself (after 10 min) is causing some expansion of parts (maybe a bad solder joint inside the box) or is heating the control unit to the point beyond which a specific part exeeds it design peramiters and fails to function. Reroute the hose or relocate the box.

Rick