Tacho readings and fix

[debruiser]

Hi,

Got a Series 3 with the 186 conversion. Had a tacho in the centre console but was apparently wired wrong :confused:

I bought a new one from supercheap and put that in and wired it as per instructions ie. off the - side of the coil not the +. but it reads that at 80km/hr I'm at 5000rpm and at 90 i'm doing somethign like 6000.... now I hit 100km/hr on the weekend so either i've got one pimped out 186 with some super low gear ratios OR my tacho is wrong. I checked the switch on the back about 4 times to see that it was on the 6 cyl option.

Help please......

[manic]

it only has a cylinder selector switch? I've not installed one yet but I have been looking at whats available and how to install. It would appear that most tachos have an adjuster pot of some sort as well as switches. Apparently some alternators also have an RPM output adjuster because of varying pulley sizes.

From what I have read there is rarely a simple switch setting that gets you accurate RPM from your alternator.

You should have a fair idea of what your engine idle speed is so play the switches and adjusters till you get a reading that matches.

If you want super accurate you may be able to use a timing light on the crank to tune the tach.

[debruiser]

Thanks Manic, I'm going to do some research along those lines. Maybe I shouldn't have gone to supercheap to get a tacho.... live and learn I guess :(

[bee utey]

From memory cheapie tachos should have a sensitivity adjuster as electronic ignitions can overwhelm a tacho set for points type systems.