jzd14 Posted March 30, 2003 Share Posted March 30, 2003 ok, i finally got the msd working with my pertronix...i had to ask around for a page convienently missing out of my msd instruction manual anyhow, i have a 280z tach in my 240z (i installed it like JTR said to, even with the resistor) the voltage sensing wire from it is currently plugged into the tach port on the msd i bought the tach adapter #8910 and wired it in and now my tach works for only 1-3seconds when i first start up the car it seems to be that the longer the car sits there without running, the longer the tach will work when i start it up...the max seems to be about 3 seconds though then the needle drops off i tried using the supplied diode and that didn't allow the tach to work at all i know others of you have had these same problems i'm looking for tips on what i should do to get this thing working...i will entertain any ideas i'm not ready to go the autometer route yet though, i want to exhaust all possibilities of getting this tach to work first thx Quote Link to comment Share on other sites More sharing options...
speeder Posted March 30, 2003 Share Posted March 30, 2003 You need to be very sure that any resistor in the car's tach input line is removed and bypassed. I use an MSD 6AL with an 8920 adaptor with the 280Z tach on my car - the 8920 works with either white wire or magnetic triggering - its input connects to the tach connector on the 6AL and its output goes to the tach. Quote Link to comment Share on other sites More sharing options...
jzd14 Posted March 31, 2003 Author Share Posted March 31, 2003 speeder- so i should bypass the 15000 ohm 1/2 watt resistor that JTR told me to put in line with the voltage sensing wire? i'm just curious, but why does JTR even make you put that resistor in? thx Quote Link to comment Share on other sites More sharing options...
speeder Posted March 31, 2003 Share Posted March 31, 2003 Yes - Take out the resistor. Probably needed when not using an MSD. Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 31, 2003 Share Posted March 31, 2003 If you are using a 280Z tach, I don't think ou ned the tach adapter. Correct me if I'm wrong, but the MSD puts out a pulsed voltage signal. The tach adapter is only required of you are using an early 240Z tach, which is a current sensing type. I don't think you need the resistor either, but I don't think that is causing the tach behavior. Seems like a capacitor is charging up some where in the circuit. Do you still have a condensor in the circuit? Pete Quote Link to comment Share on other sites More sharing options...
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