C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
Sponsored by:
Sponsored by:

Rocker arm adjustment

Thread Tools
 
Search this Thread
 
Old Sep 25, 2003 | 10:12 PM
  #1  
ill_driver's Avatar
ill_driver
Thread Starter
Advanced
 
Joined: Feb 2003
Posts: 93
Likes: 0
From: Cleburne Texas
Default Rocker arm adjustment

I have a few rocker arm adjustment questions. I started out with my heads off and piston 1 was at TDC. I put the heads on and connected all the rocker arms. I followed the Chilton's adjustment procedures as follows :
With piston #1 at TDC adjust - Exhaust: 1, 3, 4, 8
Intake: 1, 2, 5, 7
Rotate the crankshaft one full revolution and adjust - Exhaust: 2, 5, 6, 7
Intake: 3, 4, 6, 8

I checked and double checked all of my settings. In tightening the rocker arms I tightened until the pushrod could not be freely turned then gave one more crank. I noticed when I had the heads off that 1 and 6 were both at TDC, and when I rotated one full turn, it appeared that it returned to the same position - 1 and 6 at TDC.

My question is after all of this I still had a lot of play in some of the rocker arms (enough to slip the pushrod out). I know this is not how it is supposed to be, but what did I do wrong?
Thanks a lot,
Karl
Reply
Old Sep 26, 2003 | 03:10 AM
  #2  
IronJen's Avatar
IronJen
Abby Normal
Supporting Lifetime
20 Year Member
Veteran: Marine Corps
Community Builder
Liked
 
Joined: Dec 2001
Posts: 53,360
Likes: 92
From: Press "2" for English
Default Re: Rocker arm adjustment (ill_driver)

o.k. first off, did you pre-soak your lifters? it's not just for laundry anymore! seriously, you should have had them sit in a tub of clean oil for at least a few days prior to installation. many people, including me, recommend periodically tapping the plungers with an old push rod and light hammer to help 'burp' them too.
i'll assume you did that.
the other thing is when you first started, you made sure the #1 was in TDC by the cam position as well as crank position, right? as you noted, at the TDC mark on the balancer, both 1 and 6 are TDC. the cam is the determining factor here. with the intake manifold off, this is very easy to confirm because the #1 lifters should be sitting almost level with their bore. the #6 will have one (don't remember which) sticking up about 1/4" above the bore, indicating an open valve condition.
this is absolutely critical. if you are at all unsure about this, you must double check it. if you attempt to start the engine this way, some valves may contact the piston while the rockers on others will completely fall off the pushrods.
now if you did presoak the lifters and you also tightened them according to the book, then all is most likely o.k. what you probably have done was while rotating the engine, the valve spring pressure squeezed the oil out of the lifter. this condition will, of course, correct itself once you have oil pressure.
having said all that, this is where i'm opening myself up because i don't like the way the book recommends. it's just my preference, but i like to start with #1 and then tighten each cylinder in the firing order. i also only turn down 1/4-1/2 turn past the initial resistance. that gets you close enough to make your adjustments prior to cam break-in, which is shortly after you first start the engine.
my thinking is i'd rather run a little loose at start up than crank down with some preload and bend a couple valves.
Reply
Old Sep 26, 2003 | 08:14 AM
  #3  
redwingvette's Avatar
redwingvette
Safety Car
Supporting Lifetime
20 Year Member
Active Streak: 30 Days
Active Streak: 60 Days
Liked
 
Joined: Aug 2001
Posts: 3,683
Likes: 201
From: Waterford Mi
Default Re: Rocker arm adjustment (clutchdust)

There are two top dead center positions for each piston, the compression stroke and exhaust stroke. The difference is cam position. If you are looking at the #1 cylinder, if you can rotate the crank 90* in both directions and the push rods don't move up or down, than you are in the compression stroke position. If you are in the exhaust position, you can rotate the crank 90* and the push rods will move. I was taught to put it in the #1 at TDC compression stroke and adjust both valves, rotate 90* and set both valves on the next cylinder by firing order, rotate etc... until 2 full rotations bringing you back to the #1 cylinder.
Reply
Old Sep 26, 2003 | 08:45 AM
  #4  
Edzred72's Avatar
Edzred72
Le Mans Master
10 Year Member
 
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Default Re: Rocker arm adjustment (ill_driver)

A mechanic gave me a sure fire way to adjust valves, that eliminates the guess work and variances in the push rod"feel" method. Using a .002 feeler gage between the valve stem and rocker, tighten the rocker adjusting nut till the feeler gage is snug (0 lash) then tighten the nut accordingly. (1/4-1/2 turn) depending on your preference. Worked the best for me!!!!!
Eddie
Reply
Old Sep 26, 2003 | 09:26 AM
  #5  
ill_driver's Avatar
ill_driver
Thread Starter
Advanced
 
Joined: Feb 2003
Posts: 93
Likes: 0
From: Cleburne Texas
Default Re: Rocker arm adjustment (clutchdust)

Thanks a bunch guys. That makes a whole lot more sense to me now. The only question I have now is if I want to go back and redo the way I did or do it by firing sequence. What is the firing sequence? And is it pretty necessary to soak those lifters? I guess I need to go pull those out and dump them in some oil... Thanks again.
Karl
Reply
Old Sep 26, 2003 | 10:35 AM
  #6  
IronJen's Avatar
IronJen
Abby Normal
Supporting Lifetime
20 Year Member
Veteran: Marine Corps
Community Builder
Liked
 
Joined: Dec 2001
Posts: 53,360
Likes: 92
From: Press "2" for English
Default Re: Rocker arm adjustment (ill_driver)

some may disagree with me, and it may not be a written rule, but i think it's pretty necessary to presoak them. sorry. you should be able to find the firing order in you book or it may even be cast into your manifold but just in case it's: 1-8-4-3-6-5-7-2
Reply

Get notified of new replies

To Rocker arm adjustment





All times are GMT -4. The time now is 11:13 PM.

story-0
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-1
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-2
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-3
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE
story-4
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-5
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-6
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-7
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE
story-8
10 Revolutionary 'Corvette Firsts' Most People Don't Know

Slideshow: 10 Important Corvette 'firsts' that every fan should know.

By Joe Kucinski | 2026-04-29 17:02:16


VIEW MORE
story-9
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE