Tach bounces at startup - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old Aug 3rd, 14, 09:32 AM Thread Starter
Tech Team
Howard
 
Join Date: Mar 2014
Location: Orange Park, FL
Posts: 38
Tach bounces at startup

I searched and found lots of issues with using HEI ignition and either OEM or aftermarket tach but I couldn't find the issue I am having.

I replaced my factory tach in my 69 camaro with the reporduction OER tach. The factory tach worked fine until I accidentally broke the needle off. The car has a completley stock ignition. I grounded the tach wire along with the headlight switch. I double checked the ground and it is good.

The issue I'm having is that the needle goes crazy when starting the car. Once it is started, it works fine but there is a small amount of movement when I use the directionals. The start up movement is so bad, it looks like it could snap off the needle. It actually goes from negative RPM to 5K really quicklly and bounces around erratically until the car starts.

I got the part and directions to make the tach filter but everyone says it is for HEI ignition. I'll probably go ahead and try it anyways but since I shouldn't need it, I thought I would post here first to see if anyone had other ideas.
hlasagna is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old Aug 4th, 14, 03:19 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 32,010
Garage
Re: Tach bounces at startup

Install a spike arresting diode in the tach power supply line.
1N4005, 1N4007 would work.
Install with line side to power source.
If no 1N400X, then get a 1/2 amp 16-18 volt Zener diode.
Install the same direction.

Your problem is a coil is energizing when key turns on.
If you are engaging the starter and the needle action occurs at the same time, then the solenoid coil is sending a spike through the electrical system.

Give a man a rescued dog for the health of both their souls. May 2017 ROTM Winner - Thank you!
'
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CUBS - 2016 World Series Champions - Thank you, Joe Madden enjoy your next chapter.
Everett#2390 is offline  
post #3 of 6 (permalink) Old Aug 4th, 14, 03:08 PM
Senior Tech
Steps
 
Join Date: Dec 2005
Location: New Zealand
Posts: 13,319
Re: Tach bounces at startup

Also check, if a gm type hei, the bannet connection where it goes up into the dizzy cap.. it is actually on the pin and not jambed beside it... check with a small mirror

My Spelling is not incorrect...it is creative

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Steptoe is offline  
 
post #4 of 6 (permalink) Old Aug 4th, 14, 09:26 PM
Gold Lifetime Member
Mike
 
69z28freak's Avatar
 
Join Date: Jan 2006
Location: Vancouver, BC, Canada
Posts: 6,346
Re: Tach bounces at startup

My tach does the same thing and I just installed a Petronix ignition. I wonder if there is a connection? My tach is also new. I thought it was normal, but my car did not have a tach before.

Grandma, 69.5, Z/28 Finally Done! Well almost...

My Build Thread

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
69z28freak is offline  
post #5 of 6 (permalink) Old Aug 5th, 14, 07:20 AM
Senior Tech
John
 
Join Date: Oct 2006
Location: Central Colorado
Posts: 426
Re: Tach bounces at startup

I installed an aftermarket Autometer tachometer in my '69 Camaro (stck, non-HEI ignition) and the readings were erratic and spiked frequently. I contacted Autometer and they suggested I install a 10K, 1/2 watt, resistor in the green tachometer wire. I did and that fixed the issue.

Not sure if that helps... it's an easy thing to try though.

John

Last edited by 69OlympicGoldSS; Aug 5th, 14 at 07:34 AM.
69OlympicGoldSS is offline  
post #6 of 6 (permalink) Old Aug 5th, 14, 01:34 PM Thread Starter
Tech Team
Howard
 
Join Date: Mar 2014
Location: Orange Park, FL
Posts: 38
Re: Tach bounces at startup

I contacted OER and they were no help whatsoever. The support person started talking about the tachometer feeding back through my audio system. Not sure how he even came up with that. It's a 1979 Pioneer 8 track. Not exactly what you could call an audio system .

I guess I'll start trying the diodes and resistors mentioned above but it seems like if the factory tach worked, the new electronic tach should work the same. I'm try to use original parts but this is one of the few cases where I went with a reproduction. It always seems to bite me though.
hlasagna is offline  
Sponsored Links
Advertisement
 
Reply

Tags
tach, tachometer

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome