Tachometer Flickering at Low RPM - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
LinkBack Thread Tools
post #1 of 6 (permalink) Old 05-30-2007, 11:29 PM Thread Starter
 
Join Date: Nov 2003
Posts: 189
Tachometer Flickering at Low RPM

Just wanted to get some opinions on my tach bouncing around 200-300 rpm at lower engine speeds (<2000 rpm).

The tach jumps +200-300 rpm sharply at random times, but the engine is not following these jumps. Two different tachs have responded the same way. At higher rpms (>2000) the tach runs fine and the motor pulls hard. Is it possible there is some cross firing going on at lower rpms?

My ignition setup:

Mallory Unilite mechanical distributor
Mallory canister coil
8 mm Taylor spark plug wires
NGK V-Grove spark plugs

If you need more info on the motor just let me know.



archoplites is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 05-31-2007, 08:56 AM
Moderator
 
Join Date: Dec 2001
Posts: 2,151
Tachometer Flickering at Low RPM

could be electrical interference from the coil, you might want to try a resistor in the wire going to the tach.
67stang is offline  
post #3 of 6 (permalink) Old 05-31-2007, 09:17 AM
 
Join Date: May 2006
Posts: 1,627
Tachometer Flickering at Low RPM

You did not list the maker of the tach you own. Is it a cheapy, or $$$$$...?

You are not using an ignition module...? just the signal striaght from the coil?

If so, the duration of the signal at low RPM's maybe smaller then the tach wants to see, so it is doing it's best to count short ignition pulses.

Call the MFG of the tach and see if there are any other reports of this, and if it is normal. It maybe normal for the make of your tach.

[ This Message was edited by: Mikes66 on 6/1/07 12:18am ]
Mikes66 is offline  
 
post #4 of 6 (permalink) Old 05-31-2007, 11:56 AM Thread Starter
 
Join Date: Nov 2003
Posts: 189
Tachometer Flickering at Low RPM

Quote:
On 2007-05-31 09:17, Mikes66 wrote:
You did not list the maker of the tach you own. Is it a cheapy, or $$$$$...?

You are not using an ignition module...? just the signal striaght from the coil?

If so, the duration of the signal at low RPM's maybe smaller then the tach wants to see, so it is doing it's best to count short ignition pulses.

Call the MFG of the tach and see if there are any other reports of this, and if it is normal. It maybe normal for the make of your tach.

[ This Message was edited by: Mikes66 on 6/1/07 12:18am ]
Currently I'm running a cheapy tach (brand unknown), but also my MAC Tach/Dwell tester did the same thing.

The signal is coming directly from the negative side of the coil.

Maybe a good reason to buy a better tach?
archoplites is offline  
post #5 of 6 (permalink) Old 05-31-2007, 11:59 AM Thread Starter
 
Join Date: Nov 2003
Posts: 189
Tachometer Flickering at Low RPM

Quote:
On 2007-05-31 08:56, 67stang wrote:
could be electrical interference from the coil, you might want to try a resistor in the wire going to the tach.
Although I might buy a new tach, I'm interested in how much resistance I should run between the coil and tach to test this?
archoplites is offline  
post #6 of 6 (permalink) Old 05-31-2007, 12:21 PM
Registered User
 
Join Date: Mar 2004
Location: Puyallup, WA
Posts: 1,788
Tachometer Flickering at Low RPM

Stewart Warner gauges.............2 year warranty and made in the USA not overseas. http://www.4secondsflat.com

$199 for water, oil, voltage guages with a chrome pod.

_________________

http://www.spalisautodetailing.com/

Stroker Video http://www.spalisautodetailing.com/project/index.htm

70 Mercury Cougar 347 Stroker(415HP/440TQ), Tremec TKO 5 speed, Ford 9" w/3:55 gearing
My engine builder http://www.flowtechnicsonline.com/

[ This Message was edited by: Spali32 on 6/1/07 3:22am ]
Spali32 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum 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 for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

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