I know this topic has been covered a thousand times but here is the quick story. I have an OE Tach that I am trying to make work with MSD Ready to Run distributor with no box. I have the Tach wired to hot/grnd and the signal wire connected to neg side of coil. The Tach is slow and intermittent. I have also tried hooking the signal wire to the grey wire out of the distributor that is labeled "input Tach". This does not work either, same results on Tach. I have also tried making my own Tach filter using a 270 ohm 25 watt resistor and this doesnt help either. Is a Tach Filter and Tach adapter the same thing? Maybe I will order the Tach adapter and try it. I am out of ideas at this point. My Tach is also brand new. Thanks in advance

 

I installed a Summit Ready to run Distributor kit and my tach ran backwards so I installed a Tach Filter kit. It fixed my issues. Hope it helps you some.

 

Thanks for your reply. Coincidentally, I just received my factory Tach back today from Shannon and company at Redline Guages. I just test ran it a few minutes ago and it works perfectly. Thanks Redline Guages...strongly recommend!!!!

 

I am also in the same situation.
I have a 69 Camaro with a 350 small block (383 stroker), stock in dash tachometer.
I replaced the outdated Accel HEI Supercoil with a MSD ready to run #8360 and a Blaster coil. The Accel always worked with the stock in dash tachometer. The tach wire was connected to the yellow wire terminal on the Accel HEI, as far as I can tell the ballast has been removed from the wiring in my car.
I now have the tach connected to the gray wire that comes from the ready to run distributor and the tach does nothing. This is the way it shows in the msd instructions.