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 .

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 .

Garry

Probably a good place to leave it