Valve lash - a few questions about the process

[BTF/PTM]

I just finished setting valve lash on my car's L28 today. I followed the FSM spec, 0.007 intake and 0.010 exhaust, set with engine cold. Took me several re-checks to finally get all 12 valves to be happy, I'd set them and rotate the cam back around (using the crank bolt) to recheck and a couple would be loose or tight so I'd have to set them again. Here are some questions I came up with.

1) almost all of the 17mm set nuts felt ridiculously overtightened when I first broke them loose, took my whole body weight and in a couple cases I even had to use a cheater pipe on the wrench. The other engines I've set valve lash on all used the same "one hand tight" spec on the set nuts, basically as tight as one wrist could pull it. Is this applicable to our cars as well?

2) is rechecking with the engine heated up really needed? I've never heard of doing this until working on this particular beast. I'll certainly do it if it serves a purpose, just seems redundant.

3) in this case the engine was stone cold, hadn't been run in days so I knew it was cold. For future reference, how long does it take these engines to go from just-been-running temp down to cold?

[d240zx2]

The nuts should be tight, but your description says they may have been overtighted. You certainly don't want them loosening AT ALL.

I interpret the FSM as being an either-or adjustment. I often check and adjust w/engine cold, then recheck hot.

Four hours was/is the industry standard 30 years ago. Still may be....

Hope this may help.

[Skyhook]

When checking or adjusting HOT time is of the essence. It doesn't take much time for the valve train to cool enough to alter the lash. To see for yourself check the lash of the first valve in the process when you've completed all the rest.

[BTF/PTM]

I understand what you mean, Skyhook, this is exactly why I've never liked engines that require valve lash to be checked hot (the Toyota RE22 engine is another example).

I also completely understand that having the lash adjusters move even slightly could severely damage the valve train, but the converse is that over tightening those set nuts stretches and eventually damages the adjusting screws. I snugged the set nuts down as firmly as I could by hand, I'm going to do a final cold check of all 12 valves just for peace of mind and I'll give each set nut another tug to make sure they're all tight.

[dclamm]

BTF/PTM, I had the same thing as your #1 last weekend when I adjusted the valves for the first time, unbelievably tight lock nuts. And I too tightened them back to a lesser one hand spec. Can't believe they would come loose with that, but no idea why they were so tight in the first place. Glad to hear I'm not the only one...

And I would think if you don't get clicking (loose adjustment) or low compression (tight) the cold adjustment method should be good.