V12 tacho - to work on a V8

[101RRS]

I have a nice jag v12 tacho that will fit in my 101 dash. Any ideas how I might modify the tacho to run accurately off the landy v8 rather than the jag v12?

Thanks

Garry

[Blknight.aus]

if it picks up off of a spark lead with an induction pick up theres no mod needed. If it picks up off of the low voltage side of the coil you may get lucky and find a switch that sets the number of pots.

[101RRS]

Thanks Dave, looking at the wiring diagram, the signal seems to come from the ignition amplifier in the electronic igntion - I guess this is the same as taking a signal from the coil. I do not think there is a switch as the v12 tachos are a different part number to a 6 cylinder tach. (however the early daimler 2.5 litre v8 used the same tach but these are rarer than rocking horse poo)

Your response has prompted me to put a post on a jag forum to get the answers as I just assumed that the coil would drive the tach.

Thanks

Garry

[101RRS]

As I suspected the tacho takes its signal from the ignition amplifier which gets its signal from the magnetic pickup in the dizzy.

So I guess this is all the equivalent of the signal from a points dizzy going straight to the coil where the tacho takes its signal.

The only thing to work out is to how make it run on a 2/3 of the pulses and read accurately.

Garry

[Blknight.aus]

if its reading a low voltage pulse you can get an electronic unit to do what you're after from jaycar. (or you used to be able to, I havent looked at their catalog for that sort of stuff for ages)
Not sure how wide the scope for adjustment is if the kit is still available.

[rovercare]

2 options, 1. I send them to Heidelberg instruments and they fit a new tacho in the old surround, I have one in my LS1 Jag and another in a 1UFZE 2. it looks a relatively simple circuit to construst, so maybe Jaycar or similar

You can also get pulse altering kit things to +/- 99% I believe, which I have in mind if I ever bother to get the Tacho working in my RR

[Range Blitzer]

You could always just fit a V12 to the 101 and problem solved!! Not much help am I.
Robert.

[101RRS]

You could always just fit a V12 to the 101 and problem solved!! Not much help am I.
Robert.

Just so happens I do have a fuel injected V12 sitting in my backyard doing nothing;). I could probably squeeze it in :D.

Garry

[harry]

as suggested, to make the v12 tacho work,
fit the v12.
good thing you didn't get a tacho from a renault gordini.

[rovercare]

Just so happens I do have a fuel injected V12 sitting in my backyard doing nothing;). I could probably squeeze it in :D.

Garry

Probably a good place to leave it:angel:

[Blknight.aus]

why not get the 4 pot tach and the 12 pot tach and split the difference?

[bee utey]

I have a nice jag v12 tacho that will fit in my 101 dash. Any ideas how I might modify the tacho to run accurately off the landy v8 rather than the jag v12?

Thanks

Garry

PAINT JOB!!! Very easy to do, just mask up the areas you want to change, spray matt black, then relabel with model paint. Or just leave it as it is and impress your mates with 50% more revs than you are actually doing.:D