Determining Proper Pushrod Length With Melling Engine Parts

Pushrod length is a critical measurement for any engine that uses them, especially when rocker arms with no adjustability are used. With the popularity of the OEM LS non-adjustable rocker arms, even in advanced engine builds, determining the correct pushrod length for your combination becomes all that much more critical.

To walk you through the process of determining the proper pushrod length Melling’s Tech Director, Cale Risinger, made the tech video. It’s not a difficult process, but it requires attention to detail and calipers capable of measuring down to the thousandth of an inch.

“You’ll need the lifters installed along with the cylinder head and head gasket installed and properly torqued,” Risinger starts. With the cylinder being checked sitting at top dead center, you can drop in the adjustable pushrod. Then you can install the rocker arms and torque them down.” One thing to note during this process is to make sure your adjustable pushrod is adjusted shorter than your expected length.

Everything needs to be installed and properly torqued for an adjustable checking pushrod to be accurate. Once it’s adjusted to the point that all the slack is out of the system, you have your zero-lash length.

Once everything is torqued down, it’s time to open up the adjustable pushrod. “Unscrew the adjustable pushrod until all the slack is taken out of the rocker arm assembly,” directs Risinger. “This measurement is zero-lash. Remove the rocker arm assembly and the adjustable pushrod, without altering the adjustable pushrod’s length, and measure it.”

With hydraulic lifter valvetrains, most manufacturers and builders recommend a certain amount of lifter preload. With no adjustments available on the LS rocker arms being used in this example, that means the preload must be established via pushrod length. In this example, Melling recommends half of the lifter’s travel as the preload setting.

“In this example, we’re using an LS engine with a full lifter travel of 0.180-inch,” explains Risinger. “Adding half of that [.090-inch] to the measurement of our adjustable pushrod [7.373-inch], and that gives us gives us 7.462 inches.” Taking that measurement to Melling’s part seach, we find the closest pushrod length offered is 7.457 inches, which will reduce lifter preload by only .005 inch, and will work perfectly in this application.

With the measurement of an ideal pushrod length in this instance set at 7.462 inches, it’s time to find the closest off-the-shelf length pushrod or to order a set of custom-length pieces. With a 7.457-inch offering in Melling’s catalog, there’s no need to go custom.

Article Sources

About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
Read My Articles

Late Model LS Power in your inbox.

Build your own custom newsletter with the content you love from LSX Magazine, directly to your inbox, absolutely FREE!

Free WordPress Themes
LSX Magazine NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

LSX Magazine - The Late Model GM Magazine for Camaro

We'll send you the most interesting LSX Magazine articles, news, car features, and videos every week.

LSX Magazine - The Late Model GM Magazine for Camaro

LSX Magazine NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

LSX Magazine - The Late Model GM Magazine for Camaro

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...



Corvette Enthusiasts

Performance Driving

Engine Tech

LSX Magazine - The Late Model GM Magazine for Camaro

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Corvette Enthusiasts
  • Performance Driving
  • Engine Tech

LSX Magazine - The Late Model GM Magazine for Camaro

Thank you for your subscription.

Thank you for your subscription.

LSX Magazine - The Late Model GM Magazine for Camaro

Thank you for your subscription.

Thank you for your subscription.

Loading