Rocker arm adjustment
09-25-2003, 10:12 PM
#1
Advanced
Thread Starter
Member Since: Feb 2003
Location: Cleburne Texas
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
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
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
09-26-2003, 03:10 AM
#2
CFOT Attention Whore
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.
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.
09-26-2003, 08:14 AM
#3
Safety Car
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.
09-26-2003, 08:45 AM
#4
Le Mans Master
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
Eddie
09-26-2003, 09:26 AM
#5
Advanced
Thread Starter
Member Since: Feb 2003
Location: Cleburne Texas
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
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
Karl
09-26-2003, 10:35 AM
#6
CFOT Attention Whore
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
