Smiths Instrument Disassembly

[drdoom]

Hello,

Wonder whether anyone has experience in disassembling a Smiths tachometer? I'm trying to swap the pointer needles between 2 instruments. Google search suggestions include prying away with a kitchen fork, or twisting and pulling off but the spindle is an utterly delicate thing and neither method seems viable. 

[robertcosta]

I've done it with one of these:

https://www.amazon.com/Watchmaker-Replacement-Watch-Hand-Remover/dp/B000RB5GSI

[NG5]

Excellent video here on dismantling.

https://www.youtube.com/watch?v=ME_KKCpyJqE

It's one of a series on converting a smiths inpulse rvi tacho to a more modern rvc using spiyda's own board.

Removing the needle about 1min in.

I've done this on my europa tacho to get rid of the constantly waving needle that you get on old rvi tacho's and it worked well.

Edited March 30, 2022 by NG5
added needle removal time.

[drdoom]

Thanks for the replies chaps. Jim, I've an older tach to put in service in place of that original to the S2, purchased off eBay. It's familiar to me from my years as Elan owner, reads to 8k which better  serves the new engine build. Would it certainly be an RVI type? I am converting to direct fire spark via ECU, so a square wave output provided for tach. You'd advise a conversion? BTW, my Elan ran Lumenition from the off after restoration, never a problem with tach function on the OEM, '64 vintage unit.

Cheers 

[NG5]

The small print on the face should say RVI or RVC. Failing that the RVI has the white ign wire wrapped round the coil as can be seen clearly on the vid. The RVC doesn't. 

Not best qualified to advise if you need to convert to RVC but essentialy my understanding is RVC works with just about everything but RVI was essentially for points and may or may not work with other inputs. Hope that helps.