I recently changed out my valve seals. When I put it all back together, the car would not idle smoothly. I had a couple of rockers that were too loose. I followed the noise, and readjusted the valve lash. But now I’m wondering if I tightened the rockers too much, because after the last adjustment, the car won’t idle at all. The engine starts hard, and it dies if not revved. I checked the timing, and I believe it’s close enough to not be an issue.

I read Lar’s tech paper regarding hydraulic valve lash, but I still have questions. I took each rocker to the point where I felt resistance at the pushrod, and then I tightened each rocker bolt ¾ of a turn more. I’m beginning to think I waited too long, before tightening each rocker down for the final time.

Are my engine’s symptoms typical of a car whose rockers are too tight? Is there another possibility?

The other issue, is that I checked the freeplay in my timing chain, by turning the engine in one direction, and then reversing the direction, to see how many degrees the engine will turn before the distributor will rotate. My chain definitely needs to be replaced (8-9 degrees of freeplay). But the car ran fine before I started all of this. Is it possible the rough idle and bucking engine caused the timing chain to jump a link?

Any help you offer is greatly appreciated. Thanks in advance. As info, I have a mostly stock (headers, no ps, no a/c) 77 L-48 with 120K.

 

If You tighten them too much I believe the valves do not close completely, causing a substantial loss of compression. Anyway if these are Hydraulic lifters,
the way I always did it was to take the valve cover off and start the car (at idle) then back off (one at a time) each rocker until you hear it just start to clatter, (this is close to zero valve lash) and then tighten 5/8 turn more, repeat this process with all rockers. I hope this helps it is the way I have always adjusted hydaulic lifters although it can get a little messy from the oil that drips on the headers, work quickly!

 

You can adjust them hot and running but it is verrrry messy, especially if your car won't idle. Someone here must have the info on which cylinders have closed valves at a given time, or you can just rotate the engine by hand and do each cylinder individually. I usually do it cold unless I have some oil clips or cut valve covers. You shouldn't really reverse rotation on an engine, especially high mileage ones, becasue it CAN jump the timing chain, but it sounds more like valve lash.

 

I just remembered that "compcams .com has a tech dept on how to adjust them cold. I always like to hear the clatter, then I know its at zero lash, and all you need is a can of "engine brite" but if this engine wont idle, then it s a different story, good luck!

 

You don't need to listen for clatter. You can find zero lash while the car is at idle by feeling when the pushrod stops spinning. That is zero lash, then you can tighten them down a FULL turn. Not a half or 3/4 a FULL turn. Hope that helps ya. By the way, take some valve covers from the junk yard and cut the tops of to adjust the lash while the car is running. That way you won't have oil spillage. :cheers:

 

why would you do that, when you could just hear it clatter? and if the engine is running, why would you want to stick your fingers in hot oil and moving parts? I am not sure but, one turn seems excessive!

 

If you didn't get the valve on the base circle the adjustment won't come out because the lifter is still up. There is a proceedure for doing this but i cant remember what it is. Has something to do with doing the intake just as the exhaust begins to open and doing the exause just as the intake closes. I'm not sure if thats the way it goes. I always try to adjust with the intake off cause you can see when the lobe is down. Someone here has to know the proper timing of the valves for adjustment purposes.

 

WHEN I GOT MY COMP CAM THEY EXPLAINED HOW TO DO THIS COLD. I HAVE TO BELIEVE THAT YOU CAN FIND THIS SOMEWHERE ON THEIR WEBSITE.

 

Hey everyone, thanks for all the advice. Sure as anything, the valve lash was way too tight. I went back and adjusted everything with the covers off. Actually being able to hear what was taking place, as the car was running, worked a lot better than doing it by rotating the crank. I don't know for sure, but I think this might be especially true for high mileage engines, such as mine. I could actually hear the engine idle change as I adjusted the nut back and forth. Then finished up with a little timing change and BAM, the car was fine. This is a huge relief. Thanks again for all your help. This forum never ceases to amaze me at how helpful everyone is.