Your donations help keep this valuable resource free and growing. Thank you.
|
AMC 258 valve lash adjustment |
Post Reply |
Author | |
77cj5
AMC Fan Joined: Jul/22/2017 Location: St. Louis Status: Offline Points: 2 |
Post Options
Thanks(0)
Posted: Jul/22/2017 at 1:43pm |
Is there a proper procedure for adjusting the lash on my 1977 4.2L (258)
|
|
FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
Post Options
Thanks(0)
|
It originally used hydraulic valve lifters which have no lash adjustment. The lifters are preloaded (the pushrods compress the lifter slightly) if all the valve train geometry is correct. If the preload is not correct, it's either due to worn parts or machine work that has been performed. The preload can be adjusted by using pushrods of different lengths. Preload is checked on each lifter one at a time by making sure the lifter is not riding up onto the cam lobe (there are various methods of determining this) and loosening the rocker arm capscrew for that lifter. While spinning the pushrod between your fingers, slowly tighten down the rocker arm until the pushrod resists spinning. This is zero lash. Continue tightening the rocker arm capscrew until it bottoms out on the cylinder head and note how much it turned from zero lash. Each complete turn is about .080" of pushrod travel. 1/2 to 1 complete turn is about where you want to be.
|
|
1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
|
Post Reply | |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |