Ballast resistor / rev counter

#1
If I put a 12volt coil on, can I just run a new wire from the rev counter to the coil to bypass the ballast resistor wire ? will the rev counter work ?
 
#2
Hello Dave - I would like to use your post to raise your question with the group again, due to the absence of any replies.

I also plan to bypass the ballast resistor due to upgrading the coil and spark amplifier.

Advice requested please, if wiring to the Rev Counter needs to be updated.
thanks
Simon
 

sdibbers

Well-Known Member
#3
I converted to a non ballasted 12v system a few years ago on my 1969 2000TC. I run the wire via the tacho with the new wire looped through the pickup on the back of the tacho. Make sure you loop it the right way around. If its the wrong way around it won't pickup the pulse and not move.

The reason you have to do this is is because the resistor is hidden in the wire that goes from the points to the coil via the tacho. Unfortunately the resistor is pretty well hidden within the loom so tough find and remove.
 
#4
Thanks for the advice Steve - I'll check the run of the wires.
Also my 74 model has the latter RCV Tacho (sensing voltage) rather than the earlier RCI (current sensing) and so with the feed direct from the fuse box, there is a fighting chance the tacho will read OK. to be confirmed.
Thanks,
Simon
 

sdibbers

Well-Known Member
#5
Thanks for the advice Steve - I'll check the run of the wires.
Also my 74 model has the latter RCV Tacho (sensing voltage) rather than the earlier RCI (current sensing) and so with the feed direct from the fuse box, there is a fighting chance the tacho will read OK. to be confirmed.
Thanks,
Simon
Mines RCV too. They work with electronic modules like the magnetronic unit I have fitted. The RCI type don’t work with electronic ignition.
 

jp928

Well-Known Member
#6
Just looking this up in the wiring diags to see if my tacho is RVI or rVC. On sheet 7, RHSTRG. S2, 3500 C chassis,or 3500S D chassis.....there are 2 items marked 34. The top most one looks like the tacho, and should be numbered 37. Where most earlier diagrams show wiring feed through coil and then through tacho to dizzy, sheet 7 shows one coil lead going to dizzy, and a separate wire going to tacho ('34', s/b '37'), with a separate power lead to the tacho, and also out to earth. My reading of RVC vs RVI says this makes these tachos RVC, ie voltage pulse triggered, not current triggered.
Comments ?
 
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