Using valve Lash to make valve train quiet

[Yspen]

This thread refer : https://forum.ih8mud.com/60-series-wagons/402283-hi-po-camshaft-valve-bounce-clearance.html

Instead of getting new springs I decided to call Delta cams and ask them if I could make the valve lash smaller in order to make the ( extremely ) noisy valvetrain quiet.

They said of the KC859-250s cam ( 0.383" valve lift )

The new grind is a little more aggressive but nothing that requires more spring. try the tighter lash and see if that's better .
I would run the lash at .010 and see if that helps

So for now I have reverted to stock specs :
Int valve lash 0.008" and exh valve lash : 0.014"

The car runs quieter and the cylinder compression is higher
Left is before and Right is after

How does this now affect my cam duration / overlap and eventual powerband on my engine ?
From Crane cams website :

Using Valve Lash to Help Tune the Engine

The engine only responds to the actual movement of the valves. Since the valve cannot move until all the running clearance (valve lash) has been taken up, the amount of valve lash you use affects the engine's performance. For example, if you decrease the amount of (hot) valve lash, the valve will open slightly sooner, lift higher, and close later. This makes the camshaft look bigger to the engine, because of a slight increase of actual running duration and lift. If you increase the amount of (hot) lash the opposite occurs. The valve will open later, lift less, and close sooner.

This shows the engine a smaller cam with slightly less actual running duration and lift. You can use this method on a trial basis to see what the engine responds to and keep the setting that works the best. Just remember, the more lash you run, the noisier the valve train will be. If the clearance is excessive it can be harsh on the other valve train components. Therefore, for prolonged running of the engine we do not recommend increasing the amount of hot lash by more than +.004" from the recommended setting. Nor do we recommend decreasing the hot lash by more than -.008".

A intake valve that closes later actually suits me as my Dynamic compression is a bit in the high side and that will lower it .
It opening sooner will increase overlap , decrease vacuum and increase duration making me lose low end torque but gets me closer to a 260 cam character .

I still intend getting new springs but for now I am not being driven crazy by the tapping from the engine .

 

[lehiguy]

I did this very thing for years and years with a stock cam (and I have had many heated aguments with some Mudders who are terrified by anything that is not stock.) I ran .005 intake and .007 exhaust. Very quiet and slightly more poop. There is no real risk to this as long as you keep some clearance and don't allow it to become zero or less. I did my lash once a year and it was never far from where I left it. For the record, cold vs. hot clearance is less than .001" of variance. Good luck!