Smiths tachometers
Turbo Mini Forums

I have got a pair of tachos from I believe an old MG, one is -ve earth, and t'other is from a +ve earth vehicle but has been repolarised (so im told) for -ve earth.
The wiring on the rear of them is different on both, the originally +ve earth has what appears to be an inductive pick up on the rear, where the I believe the Lt side of the ignition wiring passes thru to give the singnal (emf).
The -ve earth tacho has bullet crimps on the rear, when dismantled, inside it has a similar style emf pickup, but bigger.
I was wondering if anyone knows if either of these could be used in a mini, or do they both need the Lt side of the ignition to pass thru them, I have no experience with old Mg's so if any one can shed a little light, it would be nice!
Thanks
Shane.

Attachments:

594.33kb

561.67kb

93.39kb

498.84kb

Metro turbo weekend driver,Mini turbo in the making again!

http://www.mgexperience.net/article/neg-convert.html

http://freespace.virgin.net/tommy.sandham/..._conversion.htm

Should find what you want
Regards
Dave

Cheers guys but that doesnt really help, I should of really put in that post, was planning to use Mj!
Sorry.
Shane.

Hi,
I don't think either of those will work with MJ as the MJ unit will just send the pulses down the cable to the tacho, theres no current loop to operate that type of tacho.
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

All this is from distant memory so don't shoot me down, check for yourself.
The tacho's you have are Smiths RV1 and RV2 types. The RV1 has the external inductive loop.
I don't know if RV1 will be OK with MJ
RV2 should be OK, I think the output from MJ is pin 12? Connect this to tacho and it should work.
No doubt someone will put me right if I am wrong.
Regards
Dave

Thanks again, sorry again for that, both tachos have RV1 on the clock face so guessin thats a nono to both.
Thats what I thought Gavin, but just wanted to double check.
Shane.