speedo problems

[PaulN]

This may help with RPM vs speed. I used it when I converted my Mk1 Tacho to digital.

Thats a neat spread sheet ..thanks itl help
p

[PaulN]

Just an up date
I picked the car up ..gearbox sounded great no clanking and very smooth changes with just a small soft clunk when coming to a stop
Great service
On the way home I started the GPS speedo app at 60 on the app I was actually doing 64-65 so the speedo is out slightly but the revs are way off
4,000 revs at 60mph ..so I do now think that the rev counter is out of calibration ..there is nothing else it can be
I have the link for the guys that do the rebuild ..Il get it stripped out and shipped and update the post on their findings
Thanks for the input its all been a great help
P

[Goldstar]

Paul, nothing revolutionary I'm afraid but if you have electronic ignition and your tacho hasn't been converted to accept a signal from the electronics rather than points (electronic ignition needs RVC, points RVI), that may not be helping. Probably not the cause of your problem, per se, as it usually shows as a "bouncing around" of rpm rather than a high but steady reading but worth knowing if you are about to spend money on a tacho refurb.

[Bob Heritage]

Has your diff been swapped for a higher ratio?

[PaulN]

Paul, nothing revolutionary I'm afraid but if you have electronic ignition and your tacho hasn't been converted to accept a signal from the electronics rather than points (electronic ignition needs RVC, points RVI), that may not be helping. Probably not the cause of your problem, per se, as it usually shows as a "bouncing around" of rpm rather than a high but steady reading but worth knowing if you are about to spend money on a tacho refurb.

Thanks for the info can I physically check to see if thats true or does it need a garage ?

[PaulN]

Has your diff been swapped for a higher ratio?

Hi Bob
Yes that has been checked and I have the right diff ..tbh I was hoping this would be the cause

[Hughesy]

I used this guy for my Mk1 kit:

https://www.spiyda.com/tachometer-electronics.html

[Goldstar]

Thanks for the info can I physically check to see if thats true or does it need a garage ?

Its in the small writing at the 6 o clock position of the tacho Paul Screen Shot 2019-03-12 at 08.53.28.png

[PaulN]

Great thanks for the info and sorry for the late reply