TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC 6 Cylinder Engine Repair and Modifications
  New Posts New Posts RSS Feed - AMC 258 valve lash adjustment
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

AMC 258 valve lash adjustment

 Post Reply Post Reply
Author
Message
77cj5 View Drop Down
AMC Fan
AMC Fan


Joined: Jul/22/2017
Location: St. Louis
Status: Offline
Points: 2
Post Options Post Options   Thanks (0) Thanks(0)   Quote 77cj5 Quote  Post ReplyReply Direct Link To This Post Topic: AMC 258 valve lash adjustment
    Posted: Jul/22/2017 at 1:43pm
Is there a proper procedure for adjusting the lash on my 1977 4.2L (258)
Back to Top
FSJunkie View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/09/2011
Location: Flagstaff, AZ
Status: Offline
Points: 4741
Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jul/22/2017 at 11:12pm
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
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.234 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or