• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Tach problem

Share this page

TypeRboy

TypeRboy

Jedi Warrior
Offline
I wasn't sure if I asked this before, but my tach reads high ( idles at 3500 rpm.. etc ) The tach is new, positive earth, and standard point ignition. The coil is a lucas sport coil and I am not running a balast resistor. ( the tach box showed nothing about needing one..) Does anybody know what might cause this, or if the tach's are adjustable. ( this is an nos early tach bought from Lotus )

I might as well not have a tach for the good it does me.
 
[ QUOTE ]
...The coil is a lucas sport coil and I am not running a balast resistor. (the tach box showed nothing about needing one..)

[/ QUOTE ]

Probably doesn't but this is easily checked by testing the resistance across the 2 terminals. If about 3 or 4 ohms then no resistor required. If about 1.5 ohms then it needs an external ballast resistor.
 
This is on the Elan. I have a few wiring diagrams, and the harness is brand new. Everything looks right for wiring, I can't imagine how I could hook up a tach to read three or four times the actual rpm if I tried... Yet somehow it does.
 
Back
Top