Does yours have the Dis-Ras words on it. Mine says on the box that it will work with 1 cylinder? Maybe I need to call Reubin. This sucks, becuase I already installed it. I'll let you know if it works.

 

Yes, we have the same switch. According to MSD, despite being for 1 cylinder operation, the voltage is the issue. The switch is not designed for the voltage that our cars see.

89561 requires modification for voltage
8956 requires modification for voltage and cylinder

 

I talked with Reubin at MSD. Thanks for the advice! Apprently they brought a Z into the shop yesterday to test the 8956 and 89561 RPM window switches. I was told that the 89561 switch would not work with the Z, and that I needed to have the regular 8956 switch and that it needed to be modified. Luckily I have both swithces, so I am sending mine off today to get the modification.

 

These MSD jerks can't make up their minds. I just spoke to them (Ruebin) and was told that the 89561 would work once modified, but that the 8956 would be simpler to modify.

I received mine back from them on Friday and will try to install soon.

 

are there any other rpm window swithces that will work without having to modify it?

 

this is an old thread.

just buy the digital msd rpm window switch (no pills) and install it according to their 1 cylinder setup. to get an rpm reading all you need to do is tap into one spark wire off of any cylinder and you're done with the hard part.