V12 Tacho - Signal Input

Talk about the E-Type Series 3
User avatar

Topic author
AussieEtype
Posts: 620
Joined: Wed Jun 24, 2009 10:59 am
Location: Canberra, Australia
Australia

#1 V12 Tacho - Signal Input

Post by AussieEtype » Fri Sep 04, 2009 9:55 am

I want to put a V12 tacho into another vehicle but am not sure where the tacho takes it rev input from. Is it direct from the coil like older cars, a tacho generator like early e-types, from a spark plug, or from the ignition amplifier (in which case does it count every pulse or one in 12 etc).

Also - does anyone know if the V12 tacho be modified to suit a V8.

Thanks

Garry
1971 Series 3 E-type OTS
1976 Series 2 XJ 12 Coupe

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

e-bygum
Posts: 171
Joined: Thu Jan 24, 2008 5:01 pm
Location: Church Lawton, Cheshire

#2

Post by e-bygum » Fri Sep 04, 2009 2:41 pm

Garry
The series 3 tacho takes it's input from the amp via the ballast resister pack. Can't help you with the other questions- sorry.
Pete
'71 S3 2+2

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

Topic author
AussieEtype
Posts: 620
Joined: Wed Jun 24, 2009 10:59 am
Location: Canberra, Australia
Australia

#3

Post by AussieEtype » Fri Sep 04, 2009 11:56 pm

Thanks Pete - I assume that is the same as an older tacho connected to the coil - counting each pulse generated by points (in non electronic ignition cars).

Garry
1971 Series 3 E-type OTS
1976 Series 2 XJ 12 Coupe

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

e-bygum
Posts: 171
Joined: Thu Jan 24, 2008 5:01 pm
Location: Church Lawton, Cheshire

#4

Post by e-bygum » Sat Sep 05, 2009 12:30 pm

garrycol wrote:Thanks Pete - I assume that is the same as an older tacho connected to the coil - counting each pulse generated by points (in non electronic ignition cars).

Garry
I don't know if you can assume that. The wiring on mine has been altered at some time and I don't know why. I still have the Opus, ballast etc. but there is no feed from the amp through the ballast to my tacho. Instead the tacho is fed from coil -ve through what I believe is a diode. I know that several other owners have this same set-up but I have not been able to find out why. It has been suggested to me that my tacho may have been altered to allow it to work from the coil, I don't know. I have also heard it said that the amp produces a square wave form signal for the tacho, I don't know how this compares to the signal for the coil
Pete
'71 S3 2+2

Link:
BBcode:
HTML:
Hide post links
Show post links


Jagcats
Posts: 4
Joined: Sat Dec 05, 2009 11:38 am
Location: South Yorkshire

#5

Post by Jagcats » Sat Dec 05, 2009 11:57 am

Series 3 V12 takes it Tacho signal from the Ignition coil via the ballast pack or on some cars via a separate resistor, this is rated at around 10 K ohms. It counts every pulse from the coil and therefore will only work on a 12 cylinder engine. It would be difficult to calibrate it to work on an 8 cylinder engine.

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

e-bygum
Posts: 171
Joined: Thu Jan 24, 2008 5:01 pm
Location: Church Lawton, Cheshire

#6

Post by e-bygum » Sat Dec 05, 2009 2:35 pm

Jagcats wrote:Series 3 V12 takes it Tacho signal from the Ignition coil via the ballast pack or on some cars via a separate resistor, this is rated at around 10 K ohms. It counts every pulse from the coil and therefore will only work on a 12 cylinder engine. It would be difficult to calibrate it to work on an 8 cylinder engine.
What is the purpose of the white/blue lead from the Opus amp to the ballast resister connection marked 'tach', if the tach receives it's input signal from the coil?
Pete
'71 S3 2+2

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic