Tach hook up - Ford Truck Enthusiasts Forums
 

Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1973 - 1979 F-100 & Larger F-Series Trucks
Log In 


1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck

Tach hook up

Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 09-27-2013, 01:06 PM
264WSM 264WSM is offline
Senior User
 
Join Date: Dec 2011
Location: Wyotana
Posts: 148
264WSM is starting off with a positive reputation.
Tach hook up

Not exactly a Ford question but I need help with my thought process.

I have an old Case Back-Hoe (that I pull w/ my Ford) that I want to put a Tach in. It has a 4 cyl gasoline engine that spins to 2300rpm. The tach I have goes to 8000, so trying to look at 1500-2200 will be difficult. However, the tach has a switch on the back for 4-6-8 cyl engines. If I install this and put the switch on 8, will it read 4600 when I am actually doing 2300rpm??
I want my max rpms to read around 60% or so of the face. I can "recalibrate" the face with a Sparpie marker.
Reply With Quote
  #2  
Old 09-27-2013, 04:43 PM
fmc400's Avatar
fmc400 fmc400 is offline
MSEE
 
Join Date: Apr 2004
Location: Austin, TX
Posts: 10,386
fmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud of
RPM is proportional to the frequency of the switching waveform at the coil, call that FREQ, measured in cycles per second (Hz). For a 4-stroke engine, RPM = 120 * FREQ / CYL where CYL is the number of cylinders (4, 6 or 8). For a given frequency, RPM decreases as the number of cylinders increases. Therefore, 2300 would appear as 1150 if you set the switch to 8. The 4-cylinder setting is the highest you'll get.

You could just do like I did, and build your own homemade digital tachometer

http://www.ford-trucks.com/forums/11...tach-pics.html
Reply With Quote
 
 
 
Reply


Similar Threads
Thread Thread Starter Forum Replies Last Post
WTF Wiring tmos540 1973 - 1979 F-100 & Larger F-Series Trucks 20 05-09-2015 08:27 PM
intermittent tach..please help! av8theskies Pre-Power Stroke Diesel (7.3L IDI & 6.9L) 19 04-09-2015 08:04 PM
Homemade digital tach (pics) fmc400 1973 - 1979 F-100 & Larger F-Series Trucks 41 08-22-2013 09:31 AM
Another Factory Tach Question Old Hickory 1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks 10 02-26-2011 08:39 AM
390 dizzy, coil, tach wiring Need to check this charles jones FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428) 11 01-07-2006 07:59 PM


Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1973 - 1979 F-100 & Larger F-Series Trucks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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

Forum Jump



All times are GMT -5. The time now is 07:40 AM.

 

Powered by vBulletin® Version 3.8.7 AC2
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Terms of Service - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup