Today I attempted to readjust the valves on my vehicle because of a knocking sound. (See engine noise thread) Here's what I done.

Remove #1 plug to crank engine to bring #1 cylinder to the compression stroke then turned the by hand (removed fan to do this) until the line on the harmonic balancer lined up with the 0 on the timing tab.

I then adjusted the valves in the following sequence

Exhaust: 1,3,4,8
Intake: 1,2,5,7

I then turned the engine by hand to #6 firing position and adjusted the following:

Exhaust: 2,5,6,7
Intake: 3,4,6,8

I then turned the engine by hand back to #1 firing position.

The engine started however the valves were ticking quite loudly which tells me I did not do the job right. I then attempted to adjust them again but this time the engine did not start (I'm sure the engine was at the #1 firing position) Which brings me to the following questions

When loosening the rocker arm nut enough to feel lash is that when you can rotate the pushrod and then you tighten it to the point when you cannot rotate the pushrod then give one additional turn?

Is one complete turn is when you turn your wrench a full circle or is it a 90 degree turn? This is where I think part of my problem lies in adjusting the valves not understanding what is an additional complete turn is. If someone else thinks Im doing something wrong, please comment. The above procedure is from the 79 corvette service manual.

 

You maybe tighting them too much. Don't turn them down to point where the rods will not turn, just till you feel them being a little harder to turn. I like to push them up and down till I don't feel any play. Then turn down 1/2 turn. If it won't start, the valves are most likly staying open.
Bob

 

I have always adjusted Mine with the engine running. Back off on
adjusting nut until You hear a light tapping,snug the nut back down
slowly until tapping is quiet and then tighten 1/2 turn more.Some folks
like 3/4 turn more. What You are doing is trying to center the plunger
in the hyd. lifter body. To answer Your question ,one full turn would
be a 360 degree turn, 1/2 turn would be 180 degrees etc.

 

If you have stock rocker arms, this is the way to go. I think the proceedure you were using is intended for initial set up with the lifters dry. I have Comp Magnum roller tip rockers and they would not allow a wrench on them with the engine running. Mine started making noise about 1,100 miles after a rebuild. I had to use a stethoscope to find the noisy ones, turn the engine off, tighten them a half turn (180 degrees), restart and check again until all was quiet. It was a pain. God bless, Sensei

 

I like the engine running adjustment better myself. A helpful tip. Buy a set of oil deflectors for the rocker arms. Available at auto parts stores or speed shops. This keeps the oil from flinging all over the place, which can be really irritating. Another solution is to use a old valve cover with the top cut out so you can adjust the valves, but keep most of the oil in the engine. Warm up the engine to operating temp befor adjusting.

 

I'll agree that setting the lash is best done while the engine is running. It gets messy but there are ways to lessen it as mentioned above. The hardest part about adjusting them when the engine is not running is determing when there is no resistance, zero lash. I like to back a rocker off completely to get a 'feel' for a lash that is too loose. Then tighten it while turning the pushrod. Due to the oil, things spin fairly easily. There is a knack to doing it cold. I've only done it once, and have yet to start the engine. Hopefully I'm in the ballpark when firing it up (sometime in the next week). I'll break in the cam then readjust them. One of the lesser benefits of a solid cam is the ease of adjusting the lifters.

 

Sandy,
I don't want to step on anyone's dick here because, as you can see, everybody has a way that works for them but...

I've adjusted valves on 300 to 400 small blocks (that's between 4,000 and 6,000 valves!) and I've always done it the way you described. Always dead on and I never have to go back in. (and no mess)

Your method was right, your feel was wrong. If you tighten the rocker nut until the push rod doesn't rotate you are way too tight as the oil film on both ends of the push rod will enable it to rotate by hand even after it's overtightened.

You only have to go to "zero lash". In other words hold the push rod with your thumb and forefinger and rattle it up and down as you slowly tighten the rocker nut. As soon as you no longer feel the mechanical rattle you're at zero lash. Stop there and then turn the rocker nut one full 360 degree turn like chevylit said. The lifter plunger will be centered and your adjustment will be perfect. This should only take about 20 seconds per valve.

Go back to your original starting point and redo them. The first 8 at number 1 fire position and then the second 8 at number 6 fire position.

Good luck,
Greg

 

 

Did you remove the dist. cap and see the rotor pointing at #1 contact in cap to make sure you were on the comp. stroke and not the exhaust stroke?You could do that by looking at valves but not after you had adjusted them.

 

Lars has a paper in the tech tips section under "Other" in the menu bar that details setting valve lash.

 

Lars has a paper on this and it worked well for me. Hope that helps

 

Learn from this man.

Stop listening to the boys.

 

i agree.....

 

Not to beat a dead horse here, but if the OP had adjusted the valves out of sync, (on #6 when he should have been on #1) the valves would have been so far out of adjustment (half too tight, half too loose)the car would never have started.
The OP is also an auto technician for Jaguar, not just some backyard monkey, so when he tells me he's sure he was on #1 fire position, I assume he's correct.

 

Greg--What if the first time he was on #1 (the engine started)Then the second time he was on #6(that time the engine didnt start)?As you know its easy to do.I just didnt see how he could be so far out the second time on his adjustment that the engine didnt start and that seemed to make sense. Roger

 

Hi Roger,
From this part of the OP's description I understood it to mean on the second adjustment he put one full turn on all valves after he had tightened them to the point where he could no longer rotate the push rod by hand. This would definately have had all 16 valves adjusted way too deep to the point where none of them would be closing when the engine was turned over. Consequently, the no start second time around.
That is pretty easy to do. If you've ever adjusted valves with the motor running, and you rotate a little too far when tightening, you get an immediate dead miss when the valve in that particular cylinder isn't closing. Back the nut off, miss goes away. If you multiply that overtightening by 16 the engine simply will not start.
Greg

 

Sounds good and your probably right but after hearing him ask what a full turn was and was that 90 degrees I guess I second guessed him a little bit

 

 

Are you sure what type of cam you have in the car? Unknown to me my car had a solid cam in it when I bought it and I tried adj the valves like a hyd cam, later blew a piston to hell

 

EOIC. Exhaust begins to Open, adjust the intake valve. As the Intake is Closing, adjust the exhaust valve. Do this one piston at a time following the firing order to save yourself cranking time.

Hydraulic lifters want only half a turn of preload. Lightly screw the rocker arm nut until you begin to feel resistance (when you are about to compress the lifter) then it's a half turn more from there.

Then crank the engine with the hot wire disconnected from the distributor to build oil pressure before you fire. Then fire it up.