The taco in my 76 clubman has been playing up since I installed a pulsar dizzy, it is showing the rpm to be about 1000 more then it should, i have checked all the connections and they are all good.

Then another strange thing happened the belt on the alternator came loose and the alternator stopped working, the taco then started to show the correct rpm but after tightening the belt the taco was 1000 rpm off again.

What is going on??

Maybe your alternator is overcharging and voltage is too high.
Or the alternator is just old.. the Smiths one we have in Barney reads correct on cold days and 1500 rpm high on hot days. (It probably needs a capacitor in it changed, a common prob on old Smiths ones).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

taco




tacho

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Too many cars, and too little time.

I have had the tacho fixed and it is still off by around 1000 rpm down low and around 2000 rpm up high unless the alternator is disconnected, is there a way to check if alternator is overcharging? It is fairly new about 1 year old now. I only started having this problem after fitting a pulsar dizzy is it possible that this could be causing a problem?

RVI type tachos dont work with electronic distributors, they need to have an electronic conversion done as I discovered when I bought a 123 ignition.

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

what does a conversion involve and what was the cost

Yes -Could you please explain more about tacho's with electronic dizzy's,as I have some PerTronix distributors arriving soon.One is for the LS and the other for GT.Thanks.

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Others on here will probably know more than me, I'm not a mechanic or electronics person, however, I just bought a 123 electronic ignition and read the instructions. It states (view on the website, just google 123 ignition) that RVI type tachos (which my old smiths one is, its printed on the face of it) will not work with electronic distributors (don't know if they mean 123 only or all) due to the wiring. They then suggest two places that do electronic conversions to RVI type tachos (both overseas). I ran a thread on here a few weeks ago and someone said it can be done somewhere in Sydney and cost about $120- I think. I am going to check with Roger Howard (a mini racer) of Howard Instruments in Heidelberg here in Melbourne to see if he does it. He restored the tacho. Thats about all I know. Cheers.

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

Thanks for that-Once the PerTronix arrive there could be instructions about what to with the tacho's as well.I'll let you know

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I went and asked an instrument repair place the other day about the original tacho not working with the electronic dizzy. To get the tacho to work the circuit board inside the tacho has to be changed to one that can handle the pulses made by the electronic dizzy and it is quite expensive around $170.