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I have a 66 Chevy truck C10 Straight 6 250 one of the rocker arms is noisy, how do you adjust them or do you just tighten the nut all the way down the lifters are hydraulic I would like to do it with the motor off

Thanks

First, determine whether or not the pushrod at the noisy valve is moving up and down the same distance as the rest. One reason for excessive valve noise is a worn-out camshaft lobe. This doesn't have to be a precision measurement, but if there's a noticeable difference in pushrod travel there's no point in attempting an adjustment.

OK, no noticeable cam wear- - - - -on to the adjustment procedure. The firing order is 1-5-3-6-2-4. Cut it in half, and put the first half over the last:

1 5 3
6 2 4

The nunbers aligned vertically are "companion cylinders"; the pistons come to the top of the stroke at the same time, but they're one turn out of phase for valve operation purposes. When #1 is at the top of the compression stroke, #6 is topped out at the end of the exhaust stroke, getting ready for intake. This is the key to a good valve adjustment. Get the exhaust valve closing, and the intake on the same cylinder opening, and the companion cylinder is in the right position for a valve adjustment.

Turn the engine over clockwise from the front by hand (or with a socket on the crankshaft nut) and watch the #6 cylinder valves. The exhaust valve will open, then begin closing, and the intake will start to open. This positionis called "rocking" with both valves open about the same distance. Go to the companion cylinder (#1) and loosen both adjusting nuts several turns to let the lifter go to its fully-extended position. Tighten the adjusting nut until the slack is just barely taken out, then turn the nut another 3/4 turn clockwise. Do the same thing on the other valve for #1. Turn the engine 1/3 turn, and the #2 cylinder valves will rock, and #5 will be ready to adjust. Follow along in sequence, rock 4, adjust 3, rock 1, adjust 6, etc. You can adjust all the valves in two turns of the engine, with no mess from splashed oil. The same procedure works with the engine hot or cold. Good luck!
Jerry

Climberman, It may help you to know which rocker is noisy.A way I use to determine the noisy one is with the engine running at a low idle to minimize oil loss,lay your fingers on the side of the rocker and you will feel the shock/vibration of the clearance taken up causing the noise.When you locate the offender take the time to shut down, remove the rocker assembly and look for a worn tip/ball/ball seat/pushrod seat and pushrod ends.All these areas of likely wear are dirt cheap to correct and may save some more serious damage such as cut off stud or damaged valve tip.It is very common for the ball and ball seat to wear causing the rocker to rise increasing the length of the assembly.Something wore causing the dimension change that is out of the adjustment range of the hyd lifter or less likely the adjustment nut could have backed off.
It works for me.

Hotrod and enginenut thanks for the help I will adjust them in the morning. Oh I forgot to tell you that there is only about 15,000 maybe 20,000 on the head and less on the engine I am not sure about the cam it should have been change but I didn't ask. It would take a while to explain why the head and engine have different mileages.

I think if the cam was down you would have other symptoms than excessive clearance.It is surprising how much lobe wear can exist and the engine still have a quiet valve train and a good idle but when the lobe is well down, if it is the exhaust you will get a regular pop back through the inlet tract noticible at first when the throttle is opened wide and as it gets worse even at idle there will be a regular popping back through the inlet.If the inlet lobe is about down the idle will still be surprisingly smooth but the cyl will miss as speed and load increases.
One thing about a worn or wearing lobe that can cause lifter noise is the lifter many times is wearing a lot as well where it contacts the cam so it shortens and gets out of self adjustment range.
Actually, wear on the lobe ramps or nose wont add clearance to the valve train and the base circle seems to not wear out at all,so it is shortening of the cam follower that gives us clearance/noise noticed with cam wear.

I've seen a new cam go down in the first 30 minutes of running if it's not broken in properly. Yes, it also cups out the bottom of the lifter, which lets the plunger top out and create the lifter noise. I've got a couple of Lunati cams lying around the junk heap with 15 good lobes, and one round one- - - - -with less than 100 laps on them around the Nashville Fairgrounds track! The lifters on those lobes were destroyed, too.
Jerry

Hotrod

Could you explain a little more on this part of insrtructions

(Turn the engine over clockwise from the front by hand (or with a socket on the crankshaft nut) and watch the #6 cylinder valves. The exhaust valve will open, then begin closing, and the intake will start to open.)

So which is the exhaust and intake and is up closed and down open or the other way around.

And then do you adjust both of the valves on #1 at the same time.

OK, the exhaust valve on #6 will be the last one in line, closest to the firewall. On the other cylinders, just look at the relationship between the intake and exhaust manifold runners and the valves to distinguish intake from exhaust. Also, as you're turning the engine, the exhaust valve on each cylinder will be the first one to open during the cycle. "Open" is when the valve spring is being compressed, with the valve end of the rocker arm moving toward the cylinder head. When you get the valves "rocking", (intake opening and exhaust closing), adjust both valves of the companion cylinder, NOT the ones that are moving!

#6 rocking, adjust both valves on #1. Turn crankshaft 1/3 turn clockwise.

#2 rocking, adjust both valves on #5. Turn crankshaft 1/3 turn clockwise.

#4 rocking, adjust both valves on #3.Turn crankshaft 1/3 turn clockwise.

#1 rocking, adjust both valves on #6. Turn crankshaft 1/3 turn clockwise.


#5 rocking, adjust botyh valves on #2. Turn crankshaft 1/3 turn clockwise.

#3 rocking, adjust both valves on #4.

Install valve cover, and crank up engine. Noise should be gone.
Jerry

Thanks man