Got a line on a 5.0 conversion however the tach is not hooked up and the builder said the tach doubles the correct reading and has it unhooked so as to not damage the tach. Question: Can I use something simple like the Baker Electronix tach adapter? This is a 1990 5.0 and the builder used all Martin's stuff and one of Jason's wiring harnesses.

 

All you need to do is adjust the adjustment screw behind the gauge face. Take a peek in there and you'll see what I mean. Get access to it, hook up another tach as a reference and turn it until its as accurate as possible.

I'm surprised the builder didn't do this. I think my wiring instructions have directions for this.

-Jason

 

Jason,
Thanks for that info. Will contact the builder and ask why it was not done.

 

Its a very simple process expecially if you have a multimeter you can hook to a plug wire to show you the actual rpms or a tuning program. I used a cheap sunpro mini tach I picked up from PepBoys the first few times and then used a very cool mulitmeter my father had and then this last time just matched the tach to what Tunerstudio was reading.

Note that with this method you still will only have about a 90% accurate tach. You sort of have to pick the 2000 rpm range where you "need" it to be accurate and then just accept its a bit off at idle and top end. The only way I found to make it completely accurate is to have a custom gauge face made up with the correct spacing and then reposition the needle so that it follows the correct rate. Setting this up was a pain but fortunatly Adam or Revlimter gauges now has the template and can just make the faces up in whatever style you choose. A whole set of faces is under $150 from him.

-Jason

 

Jason,

Again thanks for all the help and input. Not knowing these cars, was not sure whether this is a hard fix or not..Bottom line, I don't really need a tach but its nice to know that the car I'm looking at has everything working so I have less to chase down later on....