Tach Kills Engine, When Tach is connected to coil, engine quites after running for 4 minutes? Options

[struckn]

This has me really confussed. I have Pertronixs in the dizzy and a MSD Blaster 2 Coil, Carb conversion from FI, '74 four. It runs great as long as the tach is disconnected at the coil. If I plug the tach into the negative coil terminal the engine will start, run normally and the tach works perfect at all RPM's. But after running only a few minutes the engine shuts down and will not restart unless I disconnect the tach wire from the coil. Any suggestions would be really appreciated, thanks.

Doug

[underthetire]

You can get them at radio shack btw, just a ceramic resistor. May or may not be whats causing the tach problem, but worth a shot. My thinking was the tach was putting just enough extra draw on the pertronics, causing it to overheat. I may be way off base though. Could simply be the tach or wire shorting out.

[struckn]

You can get them at radio shack btw, just a ceramic resistor. May or may not be whats causing the tach problem, but worth a shot. My thinking was the tach was putting just enough extra draw on the pertronics, causing it to overheat. I may be way off base though. Could simply be the tach or wire shorting out.

I was thinking the draw from the tech might have alot to do with it too, or some how was breaking the signal from the Pertronix to the coil. Don't think I've hurt the Pertronics yet.

I keep reminding myself problems like this are part of the fun in this Hobby. Old cars are supposed to need fixing and figuring out the puzzles they throw at us makes it interesting to say the least. I also have a "68 AMX and a '69 C1O Pickup. Went threw this sort of thing with both and got them to the point that there's really not much more to do to them other then wax drive show maintain. I'm really happy with the 914. The 914's were always high on my Bucket List and finally got a nice one to make into a great one in time.