V6 tach but running a V8....

Tech questions that don't fit above forums

Moderator: Team

Post Reply
User avatar
Caprimaniac
Guru
Guru
Posts: 1060
Joined: Fri Nov 18, 2011 1:17 pm
Location: NORWAY

V6 tach but running a V8....

Post by Caprimaniac »

Hi. Posting here since it does not belong in any other tech- forum.

70’s car, coil- signal tachometer for v6 engine. Is there an easy way to have this i meter to show correct RPM with a v8- engine w/ tach installed?

Regards
RS
How to turn GURU in an instant.....
User avatar
Baprace
HotPass
HotPass
Posts: 1905
Joined: Sun Aug 06, 2006 4:57 am
Location: Henrietta NY 14623

Re: V6 tach but running a V8....

Post by Baprace »

Capri, some early tachometers had a selector setting inside the tach head on the circut board.
user-23911

Re: V6 tach but running a V8....

Post by user-23911 »

Factory tach....you want it to read 3/4 of the new reading. You're now getting 4 pulses per rev when you were getting 3 per rev before.
That means you want 3/4 of the current to now flow through the meter movement.

If for example the mechanism (meter movement) measures 1000 ohms, add a parallel resistor of 3000 ohms.
3/4 of the total current will now flow through the meter, 1/4 through the resistor.
The new combined resistance has now dropped which might upset the circuit.
1000 ohms in parallel with 3000 ohms makes 750 ohms. Adding a 250 ohm resistor in series should correct everything.

I went through this a few years ago. It even worked.
User avatar
Caprimaniac
Guru
Guru
Posts: 1060
Joined: Fri Nov 18, 2011 1:17 pm
Location: NORWAY

Re: V6 tach but running a V8....

Post by Caprimaniac »

Wow, gents. What should.a simple man like me do without help from you ST- guys.

I will check for any adjusrability, but doubt so since the gauges for 4- cyls had a different part no and rhe car never came with a v8.

I’ll purchase this oe kit of GT- gauges/ dash then, and see if I manage to convert my»racer» into a morr propper GT- car. Will have fun getting the readings right...

Thank you.
RS
How to turn GURU in an instant.....
Post Reply