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MG MGB Technical - Help with Tachometer

Dear Folks

I need some help please.

I have a 1964 mgb roadster with which I believe has a 1967 engine.

1. Will the 1964 tachometer work on the 1967 engine?
2. What tachometer cable would I need 1964 or 1967?
3. I cannot trace where to fit that tachometer cable onto the 1967 engine?

JR Grové

By 1967 the MGB had an electronic tacho.
Stan Best

Hi Stan

Thanks for your reply

Is there any way that you can make the 1964 tacho work on the 1967 engin?
JR Grové

JR. Since the early MGBs used a mechanical tachometer, as the MGA did, the only way to reuse your 64 tach would be to use an earlier model block. One which has the hole for the tachometer drive off the camshaft. I have heard it suggested that the later model blocks might have a hole bored in them to accept the earlier model tach drive, but have never found anyone who actually performed such modification. And, if it did not work out, you would have ruined your block. Much easier to source a later model tach and wire it in.

Les
Les Bengtson

You'll have to get a '67 tach and install its internals inside your Jager tach housing. Even if you could install a 3 main bearing cam with the tach drive in your engine, there is no external place on the block to connect a cable. RAY
rjm RAY

Any of the electronic tachs will work with the 67 engine, it doesn't need to be a 67 tach, the only proviso is physical size. If you want to keep the Jaeger face plate then you would have to transfer that between the tachs - if it can be attached.

It can be any of the earlier RVI tachs or the later RVC, but it depends on whether you have converted to negative earth or not. If you are still positive earth then you will need one from a 64 to 67 car, if you have converted to negative earth then one from a 67 car onwards or any RVC tach. But of course getting a tach from a 64 to 67 car is no guarantee that the car, and hence its tach, hadn't been converted to negative earth anyway. RVI and RVC tachs are wired differently - on RVI the current feed to the coil must go through the pickup on the tach, on RVC all you need is a wire from the points side of the coil to the sense terminal, plus 12v (used a fused ignition supply i.e. a green wire) and earth for both types.
PaulH Solihull

Thank you all for your help
JR Grové

This thread was discussed between 01/08/2011 and 02/08/2011

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