8 replies to this topic

[chichestermini]

Does anyone have an old smiths cable driven tachometer fitted to their mini? (preferably a mk1 mini) but i understand with this particular topic i simply cannot be fussy!

It is so difficult to track down resources online that might indicate fitment, and what it looks like running inside a mini.

I know minispares used to do a kit that ran off the end of the cam, but i have little knowledge of this once again apart from that it's not produced anymore.

Hopefully one of you bright sparks can enlighten me on this one, i'd appreciate any pictures but most of all am interested in ways of fitting one that might not have to involve major surgery!

Thanks in advance!

Tom

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[liirge]

Most are driven off the cam, it requires a different timing case and a pickup for the cam, no biggy.

Edited by liirge, 10 April 2012 - 11:35 AM.

[chichestermini]

Thanks for the prompt reply,

As for the Tachometer and Drive Cable these are still available on places such as eBay etc, but the mechanism that takes the drive from the end of the cam and the modified timing cover?

Are these still made anywhere that you know of? And have i missed any particular pieces necessary to make this work?

Thanks again

[callyspoy]

Is it not possible to use one off a Spitfire? It's driven off the dizzy. I guess not original though?

[dklawson]

The Spitfire (and other Triumph tachs) will not be suitable for connection to the cam. The Spitfire tach is not calibrated for 1:1 or 1:2 ratios. Most are calibrated for 3.55:1. That means connecting them to the cam would not give the correct speed.

However, you could transplant the Spitfire tachometer AND the matching distributor it could work. That said, early Spitfires used Delco distributors and the later ones that used Lucas dizzys... used electronic tachometers. So... if you transplant the distributor you will not likely have anywhere near the correct advance curve unless you have the Delco unit recurved to match the Lucas dizzy your Mini is likely to have.

EDIT: And by the way... the chronometric gauges are NOT the same as those used in Spitfires. They are an older, sophisticated, design used probably up until the late 1950s. While they were used on a lot of MGs, I believe most current activity with chronometric gauges is by people working on vintage motorcycles.

Edited by dklawson, 10 April 2012 - 12:05 PM.

[chichestermini]

Good afternoon to you both,

Correct me if i'm wrong or just being silly but if the tachometer is driven from the distributor, surely that is just the more common electronically pulse sensing method?

I didn't think you could mechanically drive a tachometer from the distributor, will i need a special distributor? (I just have a regular mk1 points distributor)

Ideally i'd like to look at using the smiths gauge as aesthetically it is rather nice

EDIT: I have just seen Doug's comment, (thank you Doug)

Do you think that it is possible to still keep with the Smith's Tachometer and have that running with a modified timing cover/drive mech.

Sorry to labour the point, but is it possible to still get such parts or does anyone know who could make such kit?

Once again, thank you all very much for your time!

Edited by chichestermini, 10 April 2012 - 12:14 PM.

[dklawson]

If you fit a mechanical tachometer with a drive mechanism going through the timing cover, you cannot use just any mechanical tach. The cam turns at 1/2 engine speed so the gauge would have to be calibrated for 2:1 (2 RPM on the face for every one rev of the cable). So, you will not be able to use the Spitfire/TR tachs as they are gear driven off the distributor shaft with a ratio of 3.55:1.

To use a mechanical drive you would end up needing to fabricate a drive kit for the timing cover, find a 2:1 cable driven tach, then have a custom cable of the correct size/length made. Frankly... I don't see the magic. The part/system would not be period correct nor would it be particularly accurate. Mechanical tachs typically have a range where they are accyrate. Outside of that range they can easily be off by 100 RPM or so.

Since cable drive tachs were not common on Minis even as aftermarket accessories, I would not try and do this. There are too many nice period looking electronic tachometers that could be fitted for less money and effort. If you are REALLY dead set on doing this... you could fit a tach drive generator/dynamo from an early A-H Sprite or very early MG-Midget and have that system calibrated to work with the Mini's pulley diameters. That will however lock you into using a 22 Amp generator/dynamo just to use the cable driven tach and the dynamo driven tach system is expensive to repair. Again, not worth it in my opinion but to each his own.

Edited by dklawson, 10 April 2012 - 12:27 PM.

[chichestermini]

Doug, thanks for taking the time to teach me about this.

I will look into this further and have a good think, the rev accuracy isn't all that important to me (my speedo's not that great either)
It was more about the aesthetic's as i just love the look of them!

I'll report back later on, in the now looking rather unlikely event that i've fitted one!

Cheers,

Tom

[Dan]

The Mini Spares kit included a boss that you fitted to the existing timing cover and a driveshaft that fitted into that. It was coupled to the cam by replacing the cam nut with a specially milled one that was much deeper with a slot across the face. The driveshaft had a flat end that slotted into the nut and formed a sort of half Oldham coupling to allow the boss position in the cover not being exactly centered. Not sure where you will get these cutom parts if the kit is NLA.