Morris Minor ShopMorris Down Under Forum Forum Index Classic Car Trader
Log in Register FAQ Memberlist Search Morris Down Under Forum Forum Index

SAAS tacho reading too high

 
Post new topic   Reply to topic    Morris Down Under Forum Forum Index » Electrics, Instrumentation & Security
View previous topic :: View next topic  
Author Message
GraGra
I am not the Stig


Joined: 05 Sep 2020
Posts: 2
Location: Qld

PostPosted: Sun Sep 06, 2020 9:53 pm    Post subject: SAAS tacho reading too high Reply with quote

Wondering if anyone can help with my new tacho in my ‘53 ute running a 948. I’ve wired it in but it’s reading 2k rpms at idle and off the gauge just flicking the pedal.

I have the reading wire connected to the CB terminal of the coil (old Lucas coil and running on negative earth) and even tried changing the cylinder selection switch from 4 to 6 to 8. Actually reads slightly lower on 8. I know the motor has had some work but don’t think that extended to coil/dizzy.

Installation instructions mention using a resister if gauge bouncing around. Would that clear up my reading or is there something else I’m missing? Is the coil too old or do I need some other type of adapter?

Any help is much appreciated.

https://www.shopsaas.com/assets/files/install/MuscleTachSmallFitting.pdf




Last edited by GraGra on Tue Sep 08, 2020 4:31 pm; edited 1 time in total
Back to top
View user's profile Send private message
DON58VAN
Full Licence


Joined: 25 Sep 2008
Posts: 863
Location: Sydney/Bowral

PostPosted: Mon Sep 07, 2020 4:42 pm    Post subject: Reply with quote

Hi GraGra

Sorry you are having trouble with your tacho.

Can you get hold of a 10k resistor to try? They only cost a few cents.

I can post you one if you can't easily source one.

BTW Your link below doesn't work unless the part in the square brackets at the end is deleted.


Back to top
View user's profile Send private message
GraGra
I am not the Stig


Joined: 05 Sep 2020
Posts: 2
Location: Qld

PostPosted: Tue Sep 08, 2020 4:43 pm    Post subject: Reply with quote

Thanks DON58VAN

Jaycar have an 8 pack of ‘10k Ohm 0.5 Watt Metal Film Resistors’ that say they are the same as 1/4 watt. Would these work?

Otherwise I might have to take you up on your kind offer.

PS: I fixed the link.


Back to top
View user's profile Send private message
DON58VAN
Full Licence


Joined: 25 Sep 2008
Posts: 863
Location: Sydney/Bowral

PostPosted: Tue Sep 08, 2020 6:11 pm    Post subject: Reply with quote

Hi again GraGra

The 0.5 watt ones will be fine. That just means that they can handle twice as much power. They will be slightly bigger than 0.25 watt ones, but this will be of no significance in your application. Most small resistors are metal film these days--they are perfect for your application.

Most cars built in the last 20 years or so have ECUs and so the tacho is probably optimised for taking its signal from one of those rather than from an old-fashioned distributor/coil system (known as a "Kettering ignition"). The resistor probably adjusts the input signal to make it more suitable for the Kettering system.

I'm not sure whether it will solve your malfunction, but it is simple, cheap and harmless to try.


Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Morris Down Under Forum Forum Index » Electrics, Instrumentation & Security All times are GMT + 10 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001- 2004 phpBB Group
Theme created by phpBBStyles.com | Themes Database