New engine valve lash setting
Thread Starter
Racer
Joined: Mar 2005
Posts: 471
Likes: 1
From: Hometown The best
New engine valve lash setting
Just finished building a new 350 engine and will soon be doing initial start up so I wanted to make sure I adjusted the valves correctly before I fire it up. It has a flat tappet hydraulic cam. I tighted the rockers down to zero lash or until each push rod was barley tight and did a 1/2 turn more. Is this the correct procedure. I have had conflicting suggestions like tightening one full turn after reaching zero lash.
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
Good to go
You are good to go. I roll the pushrod between my thumb and forefinger as I tighten the adjusting nut untill it stops rolling and put it down 1/4 turn . After I have done all of them I tighten them all another 1/4 turn . Just my way !
Bill
Bill
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
You have to develop a feel for these things. You may have it wrong, I lash the valvetrain with the intake manifold off and look at lifter movement while spinning the pushrod, some brands of lifters have very little resistance some have more. What you are really trying to do is to minimize the plunger collapse into the lifter body for a high performance motor. If you have compressed the plunger too far into the lifter body the motor may not run at all or backfire from lash problems keeping the intake valve off the seat during combustion.
You have to remeber the oil pump pressurizes the lifter and it raises the pushrod up while running.
Here is a link to Lunati cams for adjusting the valvetrian: http://www.holley.com/data/Products/...al/INST150.pdf
You have to remeber the oil pump pressurizes the lifter and it raises the pushrod up while running.
Here is a link to Lunati cams for adjusting the valvetrian: http://www.holley.com/data/Products/...al/INST150.pdf
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,113
From: Crossville TN
Instead of 'spinning', shake the pushrod up and down. You can feel the 'slack' in the valve train. As soon as that slack disappears, THAT is the zero lash point. Then turn it CW 1/2 to 3/4 turn to set the lifter in the center of travel.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
You have to develop a feel for these things. You may have it wrong, I lash the valvetrain with the intake manifold off and look at lifter movement while spinning the pushrod, some brands of lifters have very little resistance some have more. What you are really trying to do is to minimize the plunger collapse into the lifter body for a high performance motor. If you have compressed the plunger too far into the lifter body the motor may not run at all or backfire from lash problems keeping the intake valve off the seat during combustion.
You have to remeber the oil pump pressurizes the lifter and it raises the pushrod up while running.
Here is a link to Lunati cams for adjusting the valvetrian: http://www.holley.com/data/Products/...al/INST150.pdf
You have to remeber the oil pump pressurizes the lifter and it raises the pushrod up while running.
Here is a link to Lunati cams for adjusting the valvetrian: http://www.holley.com/data/Products/...al/INST150.pdf
Bill
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
I've seen situations where the pushrod ball fits so perfectly into the rocker cup that it would spin with the lifter plunger fully depressed. The rattle method is much more reliable, I actually go back and forth, looser and tighter with it until I'm absolutely sure I'm at zero, then tighten 1/2 turn. I think there are probably more burned valves in new engines from folks incorrectly adjusting using the spinning method than any other cause.
