I've read many posts on this subject, but I can't find an answer.

According to the MSD instruction manual, and the tech line, there is a tach filter in the wire for my tach. They say I need to bypass, or remove it. According to the guy on the phone, the filter is about 3 feet back in the harness. I can't find it. Does anyone know where it is?

What happens is the stock tach will only go up to 3000 rpms, then bounce all around. And this is only at part throttle. At full throttle, the needle drops to 0, and just sits there.
I didn't really want to add an aftermarket tach, (even though I have an extra Autoguage monster tach sitting there doing nothing!) because I can't find a good place for it to mount with out drilling holes in anything.


Thanks in advance.

 

I have seen a couple good threads about repairing the stock Tach. There is a capacitor and resistor pack in the dash that needs work.

https://www.thirdgen.org/forums/el...=tach+resistor (90-92 Tachometer fix....)

 

I had the exact same problem with my MSD install. I just bought a tach adapter from MSD for prolly around $30, easy plug and play. It's about the size of my palm and works great.

 

The tach filter is generally mounted on the firewall just behond and to the right(looking from front of car) of the tach.It's inline with the tach feed wire(white wire).You may still need the MSD tach adaptor pmpm is speaking of for your stock tach to work properly.And there are problems with the stock tach driver board as bilms01 mentions.