Rev counter and bonnet

[jemt]

Sorry if this has been asked before but my rev counter (66 FHC) seems to display a slightly different problem to others.

At first it will not move, then at around 3000 rpm it starts working (ish) but falls much slower than the revs and then just drops to zero.

Initially the gerenator wasnt working but I have changed that and now have approx 5V A.C at the cables on the back of the dash at tickover and it rises with the revs.

Just a matter of a rev counter repair or is there something I am missing? Would Speedograph Richfield be a good choice?

Also my bonnet will not stay up on its own. Is there any adjustment in the springs to hold it open? Do I just need new springs?

[abowie]

I am no expert on the early tachos, but I am fiddling with one at present. The generator will produce about 1v AC per 100 rpm, so 5v AC at idle might not be far from the money.
I contacted Speedograph Richfield last week:

"Attn Andrew.

We can service these units but we tend to convert them to run off the ignition system.so that
It does away with the generator.
The cost of this is GBP60.00 plus carriage and vat.
I hope this helps you and we look forward to your reply.

Regards
Tim


From: Andrew Bowie
Sent: 22 February 2015 01:40
To: info@speedographrichfield.com
Subject: Jaguar generator driven tacho

Are you able to service, repair and calibrate these tacho units?

Do you require the AC generator as well?

What is the approximate cost?

Andrew Bowie"

[jag68]

Bonnet springs. As you can see there are slots in the flanges on the spring struts where they bolt onto the diaphragm on the bonnet. Try moving the struts up and down on their bolts to adjust the tension on the springs. I can't tell you what direction - it's a matter of trial. Do not force the bonnet to close while adjusting under any circumstance. It's best if you take the front wheels off so you can see what you are doing to insure you are not touching the center section of the bonnet with any part of the struts etc. Don't want any inside out dents. This should work. I can't say your springs aren't tired but in my experience with a number of cars it's always been the adjustment. I'm away from my library so I can't say if the manual discusses this - you might look there first.

Terry Sturgeon