What do you think of the following procedure on adjusting valve lash. It differs from many methods I've read that use the TDC method. His claim is that.."when the cylinder is at TDC, this is not often the correct location to get the proper lash setting."

http://www.centuryperformance.com/valveadjustment.asp

Just wondering what your comments are about his technique and claim about TDC might not be the proper location for lash adjustment.

 

There are different way to set the lash properly. The thing every correct way has in common is to have the lifter on the heal of the cam.

 

Looks OK....and as mentioned...everyone has their own way. But I HATE doing it the way he describes.

Here's what I do:

I do each cylinder completely, and then move to the next.

Start at the front and bump motor until:

Intake valve is ALMOST closed. Set the ex. valve on that cylinder.

then...bump motor until:

Exhaust valve is just starting to OPEN...set the Intake valve on that cylinder.

It really is pretty simple and easy to do this way once you get used to it.

JIM

 

with Jim. This procedure don't require a lot of memorization and fool proof.

 

I agree with 427Hotrod on doing each cylinder while I'm there. But, I don't "bump" the engine with the starter...it's very inaccurate and puts a lot of wear into the starter solenoid. It really isn't that hard to turn the engine with a socket on the harmonic dampener bolt if you take all the spark plugs out.

At TDC at the top of the compression stroke the intake and exhaust valves are both completely closed. I think that web site is using a method which ensures that the valve is closed no matter whether it's on the compression or exhaust stroke.

Here's how I do mine:

1. Disconnect the ground cable from the battery and block at least two of the wheels front and back and put the care in neutral.
2. Remove all spark plugs and valve covers. If you have a hydraulic cam then you will be setting the final lash with the engine running. I recommend locating some junk yard or use spare valve covers if you've got them and cut about a 2" strip down the middle of them so that you can stick a socket on each rocker nut. Make sure you bolt and seal these covers down with silicon just like you normally would so you don't get oil all over the place.
3. Stick a socket on the harmonic dampener bolt and turn the engine clockwise while watching the #1 cylinder rockers until you see the intake valve start to close...this means that the intake stroke is finishing and compression stroke is about to start. Keep turning until the timing mark lines up to indicate TDC. Now you can be totally sure that the intake AND exhaust valves for the #1 cylinder are both completely closed.
4. Adjust the valves according to specs...tighten nut until feeler gauge is hard to slide between valve stem and rocker for solid lifters or tighten nut until push rod is hard to turn for hydraulic.
5. Next in the firing order is the #8 cylinder. The intake valve on the #8 cylinder will still be up a little bit. Turn the engine with the socket until the valve closes completely and a tiny bit more....the same amount as what you did with #1...there's won't be any way to detect the exact location...this is a feel it kind of thing...you have to feel how far you turned the engine with the socket on the #1 cylinder after the intake valve closed before it lined up the timing mark with TDC and turn the engine the same amount after the #8 cylinder instake valve closes. Then adjust #8.
5. Continue around in the firing order 18436572.
6. REMOVE THE SOCKET FROM THE HARMINIC BALANCER!!! I don't think I can stress how important this step is. Obviously also replace the spark plugs.

For solid lifters you are done, so replace the valve covers and start up the engine and listen for any clatter...if there is only a slight clatter then let it idle for a bit to operating temps and then give the engine a few quick bursts up to about 3,000RPM to seat everything. If there is still a clatter then you can adjust the valves again to make sure they are at spec...some engines always have a little valve noise, but it's never harmful to play it safe and adjust them again.

7. For hydraulic lifters you need the lifters to be in a pressurized state with the engine running...so reconnect the battery and start the engine. There will probably be some clacking noises and it will be very loud...that's fine...you might need to adjust the idle up or down to get a smooth idle.
8. It doesn't matter what order you adjust the valves in this segment, but it makes sense to adjust one head from front to back then walk to the other head and adjust them from front to back to reduce walking around. It also makes sense to adjust both the intake and exhaust on each cylinder before moving to the next cylinder.
9. Listen carefully to the clatter while adjusting. Back off the nut until you hear the clatter get louder...this is so you can distinguish the noise coming from THAT valve from all the noise coming from the other valves. Then slowly tighten the nut until the noise goes away, but listen carefully because the noise will usually come back just a tiny bit....if it does then give the nut another 1/2" turn. If it doesn't then give it just a 1/4" turn. Then move to the next valves and do them.
10. We aren't done yet...we have simply eliminated all the noise, so now we can fine tune the valves by doing them again and ensuring that the nut is tightened down just at the point where there is no noise at all, then tighten them the required number of turns indicated in the OEM specs or by the lifter manufacturer if the lifters are not OEM. When you tighten them down to specs you will notice that some extra load will occur on the engine because the valves will be staying open until the oil inside the lifters adjusts to the required level. It may take a new lifter upto a minute to stabilize the oil in all of the lifters, so let the engine idle for another several minutes, then give the throttle a few quick bursts up to like 3,000RPM to help seat everything.
11. Replace the original valve covers and take it for a spin...then listen to the valves to make sure everything is quiet. Hydraulic valves should make no noise...if you hear a clatter then you need to adjust the valves again.

Drink a beer.

 

"When the cylinder is at TDC, this is not often the correct location to get the proper lash setting."

The above statement is for a radical racing cam that has huge duration and long ramps, for the street cams we run, TDC is the point you want use. I have never had a problem and I have a big solid cam in mine.

My balancer has four marks, 0, 90, 180, 270. I have 11:1 CR and I don't take the spark plugs out, a big breaker bar is all you need to turn it over. I can't understand bumping the motor over either, I don't know how you are supposed to stop it at the correct location.

Anyway start at TDC on compression stroke on #1, 0 deg on the balancer and adjust the #1 valves, turn the motor 90 degs and adjust #8 and so on , pretty simple

 

The bumping the motor over part is fine, at least to me. You don't have to be at any particular point on the lobe as long as it's on the base circle and you aren't starting to open things.

If the intake valve is almost closed, then you are approaching TDC. The ex valve is a LONG way from doing anything..it's on the base circle and is safe to set.

If the ex valve is opening, the piston is on the way downward and the intake valve completely closed back when the piston just passed TDC. It's on the base circle and is safe to set.

The TDC part works too.....if you are on TDC of the compression stroke, then both valves will be on the base circle. The intake closed when the piston was on the way up from BDC and the intake isn't going to open until it gets down close to the bottom. You are on the base circle with both lobes and they are safe to set.

Whichever way is easier to you works fine. I just find using a remote starter button that I have permanently wired into harness a lot easier and faster. No need to pull plugs, no need to fight sockets etc down around the belts and pulleys. I can "run the valves" in minutes and know they are correct and not worry about them.

My cam is .774 lift....so it's slighly radical sorta...still runs nice on the street though!

JIM

 

I am also with Jim on this process...and agree with his comments here...

 

[QUOTE=MotorHead
Anyway start at TDC on compression stroke on #1, 0 deg on the balancer and adjust the #1 valves, turn the motor 90 degs and adjust #8 and so on , pretty simple [/QUOTE]


Thats how I do it. My balancer also has marks every 90*. It takes 2 crank revolutions to set all valves. I can't imagine lifters not being on the base circle at that point. If not on the base, the cam would have to be a very long duration cam (well over 320*) with very long ramps. If someone is running that type of cam, they'll know how to set the lash. There are many ways to set lash properly. I feel confortable doing it at 90* intervals.

 

Here is how I do mine

Valve Lash Adjustment

Every cam company is different so you need to know if they want you to set the lash when the engine is either hot or cold. You should find this and the setting values on your cam card.

You need three tools: a wrench, an Allen wrench, and feeler gauges.

1. If you need to adjust while the engine is hot (at operating temperature) remove the valve covers and pick the cylinder you are going to adjust first.

2. Hand-turn the engine in its normal direction of rotation while watching the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder’s intake valve. (Why, because when the exhaust is just beginning to open, the intake lifter will be on the base circle of the lobe, so the intake is the one we can now adjust.)

3. Using your feeler gauge, set to the correct valve lash, and place it between the tip of the valve stem and the rocker arm. Adjust until you arrive at the proper setting and lock the adjuster in place. Hold the wrench steady and tighten the center with the Allen wrench to lock it.

4. After the intake valve has been adjusted, continue to rotate the engine, watching that same intake valve. The intake valve will go to full lift and then begin to close. When the intake is almost closed, stop and adjust the exhaust valve on that particular cylinder. (Again, when we see the intake valve almost closed, we are sure that the exhaust lifter is on the base circle of the lobe.) Use the feeler gauge and follow the procedure described before in step 3.

5. Both valves on this cylinder are now adjusted, so move to your next cylinder and follow the same procedure again.


With an iron block and aluminum heads, subtract .006” and this should be the setting when cold as compared to when set hot. In other words, if you set the lash at .020 when the engine is hot, then you should read about .014 when the engine is cold.

 

Great info guys! Thanks for all the tips

 

do a search for Lars method
i found this to be the easiest to perform
similar to Jims method.

 

I have one of those fixtures that bolts onto the balencer with the three pully bolts. I installed the pully with studs and jam nuts. When I want to manually turn the engine over I just pop the tool onto the remaining portion of the studs and secure it with 3 more jam nuts. I also use the proceedure with the exhaust valve just opening, and the the intake valve almost closed. I watch the other cylenders and jump to which ever one is closest to this condition, keeping track on a piece of paper. I do intake on all cylenders then exhaust on all cylenders. What is good about the tool I use is that you can rotate the engine backwards. I find this method to be the fastest for me.