Swinging Tacho

Garrett · Post by **Garrett** » Sat Jan 14, 2006 3:48 pm

After accelerating the tacho needle oscillates by +/- 1000rpm approx. before settling down to the new speed. Is this a symptom of anything? Everything else is fine. A beautiful Winter's morning for a drive around West Cork today BTW - life is peachy sometimes.

Ian Comerford · Post by **Ian Comerford** » Sat Jan 14, 2006 5:25 pm

I had a similar problem occur on my '79 SC. First the tacho needle swung all over the place, later the chraging light came on but not very bright. Eventually turned out to be failing, but not yet failed, alternator. Took ages to confirm because it appeared to be putting out just enough charge.
Hope this helps
Ian

impmad2000 · Post by **impmad2000** » Sat Jan 14, 2006 5:34 pm

I have seen the bouncing tacho from both points gaps set incorrectly and also from low charge voltage. If you have a voltmeter, check the voltage across the battery with the engine on a "fast tickover" approx 2500 rpm, should be 14V ish. This should give an indication of a alternator problem.
Check the points gap anyway , just for good measure.
Enjoy
Tim

Ian Donkin · Post by **Ian Donkin** » Sun Jan 15, 2006 4:00 pm

As I have the same rev counter symptoms and a charge light that doesn't always go out straight away when I start her up, maybe it's time to start thinking alternator.

Mind you, I'll catch this with the engine rebuild...

Vic Cohen · Post by **Vic Cohen** » Sun Jan 15, 2006 6:32 pm

Not clear what Tacho u have, after along rebuild was one of the last things left to do on 72, 2.4 s ........................sent off for a refurb and has a new damper and all fine now , find a local instruments mender and u ll be fine ..................if its fittted with a damper in the first place

Garrett · Post by **Garrett** » Sun Jan 15, 2006 8:42 pm

Thanks for all the replies.

I checked out the points and they're ok, 0.3mm gap and clean. alternator light does sometimes take a blip of the throttle to go out. Fan belt is possibly a bit loose - about 1" play midway between pulleys- is this right?

I'll get a DVM and check the voltage across the battery / alternator function next w/end.
The tacho is VDO/std issue I think

Vic Cohen · Post by **Vic Cohen** » Sun Jan 15, 2006 10:23 pm

Just read 73 car??? U ve definitely got a damper and its likely to be ex!

IanMcLeod · Post by **IanMcLeod** » Mon Jan 16, 2006 11:54 am

Vic Cohen wrote:Not clear what Tacho u have, after along rebuild was one of the last things left to do on 72, 2.4 s ........................sent off for a refurb and has a new damper and all fine now , find a local instruments mender and u ll be fine ..................if its fittted with a damper in the first place

Vic

Do you know where you can get refurbished Tachos from? I have the same problem on my 73 and it looks like its the Tacho unit rather than anything else.

Thanks.
Ian.

Vic Cohen · Post by **Vic Cohen** » Tue Jan 17, 2006 7:06 am

It happened to be at Jaz Wembley Park , when i decided to get it done ..............he sent it off to a place in Harrow , back in 5 days ,sorry dont know who they wrere .............o2o8 903 1118 ask for Steve i am sure he ll tell u

IanMcLeod · Post by **IanMcLeod** » Wed Jan 18, 2006 6:02 pm