We installed a tach tonight in my car. Hooked it directly to the MSD box. Zero's out when you turn the key and suprisingly it's pretty spot on w/the tach in the dash. HOWEVER, I had an issue tonight and wanted to bounce it off a couple of ya. Little history first.

Tach supposedly came out of Kenny Schraders race car when he drove for Hendrick (circa '88)
Have a separate shift light hooked up and it comes on when supposed to.

Now, on the way home tonight I stayed in the gas just to see what would happen. I have the 6400 chip in the MSD box. Looking at the tach I stayed in it and when I started to hit fuel cut off of stock Ford the tach was nowhere near 6250. Wanna say it was like 52-5500. I'll have a passenger ride w/me just to see if Im right. Ideas?:

 

so its a really old tach then, sounds like thats why.

 

Problem solved. It's amazing how far off in dash stock tach's are. But, I think they are designed that way so people aren't blowing stuff up all the time.


Went to a friends house and told him about the problem. So, what we did was: Take a 3K pill for an MSD box and put it in mine. Mashed the gas and the box is working fine,,stuck right at 3k rpm. Stock in dash tach read,,,,3300 rpm. I feel better now. Worked correctly at the track tonight.