Technical Zero valve lash for solid lifters?

Yes. And I mean that in the best way. Specifically, different combinations went either way. Your situation will be different, and the first time you do it, you will know which way. Sorry I can't give a black and white answer, iron block and heads behave differently than iron block aluminum heads, behave differently than aluminum block and heads. Then factor in push rods, rocker type and material, cam type, roller flat tappet hydraulic solid. The intent of my comment was to show how I do it in general terms, that reduces the assholes and elbows hustle trying to get the valves adjusted hot while the engine is also cooling off. Hence clearances are changing if you don't rewarm the engine during valve adjustment.

Once you have done it once, I think you will agree it reduces the stress associated with getting it done. Is it the perfect way, I don't know. Like I said I've been doing it this way since I was a teenager, and it works for me.

 

The basic point here is that you are trying to insure that you have enough lash so that as the engine warms and parts expand, they don't end up holding a valve off its seat when the base of the cam is moving across the lifter face. So the cam manufacturer tells you an approximate amount of lash that "probably" will allow the valve to close and the valve train not to rattle.
Now consider that there is going to be a difference in the expansion of an engines heads as they warm up. Will your aluminum head expand the same amount as your cast iron head ? As it expands, it will cause the rocker arms axis to move away from the block and the cam inside it. Will the valve stems all expand the same longitudinally no matter what alloy they use or maybe sodium filled. Why do intake and exhaust valves have different lash settings ?No, there will be different rates of expansion. What about the pushrods, do all pushrods have the same rate of expansion? You can see that there are lots of variations in the expansion rates of the components being used, yet only one amount of lash works perfectly for all of them .......?
The people who suggested that you try checking what the lash actually is after the engine warms up, are on the right track. The idea is to have sufficient lash (or none if it works well) that once the engine is warm (which is when you need correct lash), the valves remain on their seats.
What is the solution when someone sets valves to recommended cold lash.....and the valvetrain is noisy? Do you leave it that way or do you adjust it till the tapping goes away?
In actual practice there are variations in how almost everything works. Its the end result that counts, not how you got there.

As for adjusting valves while an engine is running......do you think people don't do that? Do you think no one has ever ruined a feeler gage adjusting valves? Do drag racers have to wait for their engine to reach ambient temperature before thay adjust their valves for more lift and a few more hp? They can't always rotate an engine manually when time is of the essence. You may set your valves with cold lash and be perfectly happy with the result, but I can tell you that more than a few people have had to make adjustments because the recommended cold lash didn't work for their setup.
Hot lash setting is more important than cold lash setting because because thats what you have when all the parts have expanded.......
Read the article below.
https://www.motortrend.com/how-to/1707-how-to-set-valve-lash/

 

I agree, there can be variances. Zero is somewhat a subjective description. The point is that whatever lash someone decides works for them, it is best done when all parts are at normal operating temps. If an engine is used in heavy load situations and tends to run much hotter, the hot lash would need to be increased, or steps taken to insure the engine has additional cooling available. The one thing here is that if minimal touching of the lifter/cam occurs but the valve remains on its seat, there should be no damage. A valve spring is going to require a certain amount of pressure before the valve actually begins to move. I guess a better way of putting it would be........If a valve has 100 lbs of seat pressure when closed, how much would the spring move if there is 10 lbs of pressure pushing on it? And how much does 10 lbs of pressure affect the cam. Its kind of an area of limbo where lash might be anything from a couple thousands to zero with minute pressure. Additional clearance would only serve as a safeguard against additional heat causing additional expansion.

 

It's crazy how much it all depends on who you ask.

Motortrend:
Iron/iron no expansion to write home about
Iron/aluminum cold lash 0.006 tighter
Aluminum /aluminum 0.010 tighter

Crankshaft Coalition:
Iron/iron 0.002 looser
Iron/aluminum cold lash 0.006 tighter
Aluminum /aluminum 0.012 tighter

Power Nation:
Iron/iron 0.004 tighter
Iron/aluminum cold lash 0.006 tighter
Aluminum /aluminum 0.008- 0.012 tighter

Same goes for the method:
Cold/hot/running

Or even the way, how to find the right point to adjust the latch:
TDC/EOIC/Ellison

Frank

 

When it comes down to it, you have to make a decision as to what is logical. Logic dictates that in actual use all parts will not be cold and the clearances that matter are the ones you have when at normal operating temps.
Then the question is how do you get there from here..........
Yes there will be differences of what works and stories of how what worked for one person did not work for someone else. All I can say is that as long as you do not put your camshaft in a position where it has too much pressure on it, you won't hurt it. As long as your valves shut and stay shut and you don't hear a clacking sound, you won't hurt the cam or lifters that way either.

I'd quit worrying about what everyone (even me) tells you and set it at the cold lash recommended by the cam manufacturer. Then start the engine and see what it does.
THEN, decide if you need to adjust it any. Maybe even play around by adjusting a valve or two too loose and too tight when its warm. You will quickly see what happens and learn from it. Its not an exact science and results do vary. Not all doctors prescribe the same treatments. They just try what their experience has indicated works.

 

It's threads like these that make me want to leave this board.

 

This is definitely one of the more controversial threads that I’ve read. I truly feel that camshaft companies & engine developers/manufacturers /engineers have way more time/R&D devoted to this & I always adjust lash to their recommendations. I have personally seen hydraulic cam lash settings affect peak HP/RPM levels very slightly & can imagine solids would yield similar results. With that being said; I feel like if I can’t hear my solids; they’re to tight & need adjustment & if my hydraulics are noisy; they’re too loose & need adjusting. I do prefer adjusting both cold as in my mind the engine starts to cool off & I have a hard time feeling like my hot adjustment is accurate based on parts cooling before completed.