Can I check my Idle speed with no onboard tach?

[hdm48]

Idle speed

If your truck does not have a tach and you want to check the idle speed after pump adjustments or as part of a tune-up. Photo-tach's are available from www.web-tronics.com for about $80. These are handy units that are accurate from 1rpm to 99,999 rpm. I own one and use it to check the accuracy of the factory tachs as well as checking after tune-ups. It can even be used to check turbo rpm.

 

[BushWakr - RIP]

Another simpler and short term method is as follows:



Start the engine and let it reach operating temperature.

Once normal temp has been reached, turn on the headlights, AC, signals and if the truck is an auto trans, place in "D".

At that level of demand the mirrors on the truck should not be shaking and causing the image to be blurry... . I know, it sounds kind of foolish but it works. Normally you can get within 50-75 RPM of 800 under load as noted above.

Besides it keeps your oil pressure at a decent level under load too. .



Pastor Bob.