Author Topic: Valve adjustment Sequence  (Read 2371 times)

Offline AMXguy

  • Sr. Member
  • ****
  • Posts: 1035
Valve adjustment Sequence
« on: December 19, 2009 - 12:58:11 PM »
Is there a reason you can't just bring each piston to TDC on the compression stroke and adjust the valve lash? I have the adjustment chart but it makes no sense why you couldn't just rotate the crank 1/4 turn at a time and adjust both valves in the firing order on tdc compression.  does the valve actually start lifting as it's on TDC or am I OK to do it this way?
1970 R/T SE Challenger
 1970 Superbee
 1969 S code Mach 1
 1967  GTO




Offline vinb

  • Resident
  • *****
  • Posts: 2163
Re: Valve adjustment Sequence
« Reply #1 on: December 19, 2009 - 01:07:36 PM »
This should help...

Offline AMXguy

  • Sr. Member
  • ****
  • Posts: 1035
Re: Valve adjustment Sequence
« Reply #2 on: December 19, 2009 - 07:39:54 PM »
Thanks, that's easier to follow tham the chart I have with 4 moves.
 
 Still, why can't you bring it to TDC on each cylinder as the are on compression and adjust them then? it seems like at no time would the valves be more closed than on tdc compression? I'm not arguing with the chart I just don't understand why my way can't be as good or better. I have to assume the exhaust valve lobe is already tightening up on the lifter as the pistion hits TDC?
1970 R/T SE Challenger
 1970 Superbee
 1969 S code Mach 1
 1967  GTO

Offline femtnmax

  • Full Member
  • ***
  • Posts: 997
Re: Valve adjustment Sequence
« Reply #3 on: December 19, 2009 - 07:46:51 PM »
I have to assume the exhaust valve lobe is already tightening up on the lifter as the pistion hits TDC?
Yes.  Most performance cams have valve overlap at TDC to help high RPM power.   At TDC the intake valve is not done closing, and the exhaust valve is already starting to open.
Phil

Offline Chryco Psycho

  • Administrator
  • C-C.com Guru
  • *****
  • Posts: 36620
  • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
Re: Valve adjustment Sequence
« Reply #4 on: December 20, 2009 - 03:02:29 AM »
even on TDC firing when both lobes should b e closed a long duration cam is set more accurately doing it by the Mopar chart as you are on the back side of the lobe in each case

Challenger - You`ll wish You Hadn`t

Offline Changin Gears

  • Sr. Member
  • ****
  • Posts: 1011
Re: Valve adjustment Sequence
« Reply #5 on: December 20, 2009 - 07:45:23 AM »
I've always used the 4-position method but AMX has a a valid question.  Has anyone ever set them with 4 or 8 position method, then went back and checked with the easier follow-the-firing-order?


The goal never changes - Stop the 60' timer with your back tires

Offline quagmire

  • Full Member
  • ***
  • Posts: 567
  • Traction Impaired......
Re: Valve adjustment Sequence
« Reply #6 on: December 20, 2009 - 10:08:10 AM »
I have.  It was no different either way.  If the lifter is on the base circle it doesn't matter what order you do them in.  I just rotate the engine while watching for valves that are closing, then I rotate it slightly more once it has stopped moving just to be sure it isn't opening already.  I spend a lot less time rotating the engine when I do it that way, just have to be sure you don't miss any!

Offline Oldschool

  • Administrator
  • Permanent Resident
  • *****
  • Posts: 13195
  • Member Since 9-05-06
Re: Valve adjustment Sequence
« Reply #7 on: December 23, 2009 - 08:54:30 AM »
I have done it both ways also.  It works the same. 6 of one--half dozen of the other.  So, either follow the chart, watch the valves and rotate the engine a few more degrees after the valve closes, or set TDC on the firing stroke and set the valves for that cylinder. All should have the cam lobe on the base circle.....     :2thumbs:   
Ken  --  In Georgia

MOPAR-------"Built To Run------Here To Stay"

Offline Aussie Challenger

  • Resident
  • *****
  • Posts: 3407
  • In Kansas loaded for Drive to West Coast.
Re: Valve adjustment Sequence
« Reply #8 on: December 28, 2009 - 04:32:25 AM »
  Unless you know what you are doing and are experienced, do it according to the chart, simple peace of mind. Done once, done correctly.   :2thumbs:
  It takes a lot more time to have to strip it down again to do it a second time.   :cheers:
Dave