Use of original Tach

[wrkey]

Greetings,

New to the forum and just purchase a '67 Sprite. No speedometer but I do have the original positive earth tach. My car has been converted to Negative earth (previous owner did then when the replace the motor with a SBC 350). I want to keep the dash looking original and classic so I am looking to modify the tach for Negative Earth and 8-Cylinder function.

But I also know that there is a need for the original parts where there is an interest in restoration of them. So, before I made the modifications to the Tach, does anyone want to purchase this one? Face is nice and clean but chrome does have some pitting but not bad. Send me a PM if interested.

I will probably start the modification to the tach tomorrow (6/4/16) to change it to Negative Earth, see if I can make it work with my MSD electronic ignition (I read somewhere they won't). If I can make it work but the readings are off, I will then try to recalibrate it. If it doesn't work, I will sell it with the Negative Earth modification (clearly marked on the casing).

Comments, suggestions?

Oh, and I would like any and all suggestions for an aftermarket Tach and Speedometer that will fit the 4" holes in my dash and won't break my wallet.

Rusty

 

[dklawson]

Look on the face of the tach for the letters RVI or RVC. The early tachs are going to be the RVI type which are current pulse sensing. They will not work directly with your MSD setup. However, MSD makes an interface module that should allow your tach to work. See the link below. I believe you need their #8920 but I would call their tech support line to confirm this.
https://www.msdperformance.com/products/accessories/tach_adapters/

You can alter the calibration on some RVI tachs but I don't know if they allow enough span adjustment to convert from 4 cylinder to 8. There is a web site dedicated to owners to have changed their small British car engines to V8s. There is probably information on that message board that can walk you through both the tach interface and its calibration.
https://www.britishv8.org/British-V8-Current-Issue.htm

EDIT: I'm afraid when you are considering 100mm tachs and speedos there may not be many inexpensive and nice looking instruments. If you can define your budget a little then people here will be able to make recommendations.

 

[CaptRandy]

Look at Speedhut as possible source of replacements.

 

[HealeyRick]

Take a look at my build page to see how I used a Stewart Warner tach guts in my big Healey gauge. It will work the same for the Sprite: https://forum.britishv8.org/read.php?13,8264

 

[Gerard]

Very nice job on the Healey, Rick!

Take a look at my build page to see how I used a Stewart Warner tach guts in my big Healey gauge. It will work the same for the Sprite: https://forum.britishv8.org/read.php?13,8264

 

[CaptRandy]

Nice job there Rick, did you glue down the Reflectix bubble to floor boards or just the rugs to the top of it?

 

[HealeyRick]

Very nice job on the Healey, Rick!

Thanks, Gerard. That means a lot from one of the long-time Healey folks. Driving it is a blast!

Nice job there Rick, did you glue down the Reflectix bubble to floor boards or just the rugs to the top of it?

I did both. Reflectix was glued to the floor and the carpets glued on top of it. Could be a bad move if I was getting stuck in the rain, but it's a convertible andI can always put the top up and roll up the glass side windows.

 

[Gerard]

Yes, very impressed with the problem solving and fabrication.

What I hate seeing is the half-assed, poorly engineered way some of these conversions are done, which is more often the case than not.

Driving it is a blast!

I couldn't tell...

Thanks, Gerard. That means a lot from one of the long-time Healey folks. Driving it is a blast!

 

[wrkey]

So... I converted to Tach to Negative Earth and decided not to try to use it. Don't know if works.. but will be offering it up.