Solid roller SBC, engine in car when purchased, owner deceased. What should I set lash at with an unknown cam? Wasnt wanting to pull front of engine apart to obtain cam info. Ran the valves and the average lash is .023" on all when cold. Haven't put heat in the engine yet. Im a first time sbc owner. Thanks

That seems quite a bit cold. It's going to open up about .006" if an iron block and aluminum heads.

I would close it up about .005" but just an opinion I can't say what it should be exactly for the same reason you can't.

Most of my stuff says either .024 or .026 on the card. I do everything at .020 cold, assuming it will end up at .024 hot.

Like Curtis, I am assuming iron block and aluminum heads.

I set mine at .020 cold with iron block & aluminum heads. Below is the hot setting on cam card.

2BKING

be careful going tighter than what it is until you know if the engine can take it. Piston to valve clearance may already be tight. Or it might not be. You just don't know in a situation like this, until you pull it apart & find out.

I can't wrap my head around how the change in lash would close up the PtoV clearance?

my 2 cents is .020 would be good.curtis wouldn't tightening the valve lash open the valve further

quote:

Originally posted by rusty:
my 2 cents is .020 would be good.curtis wouldn't tightening the valve lash open the valve further

It wouldn't change peak opening, right? It just starts the lift curve sooner is my thought.

There's no magic number to lash on a cam. I have not seen +0.010" lash make any difference in performance. I went from 0.020" to 0.030 on the dyno and noticed no change. I'm sure some have different experiences, but I've just not seen it.

Less lash is better to a point. You need enough clearance for things to be happy and not cause interference, but not so much that things get sloppy.

0.020" seems to be a good number for race roller cams and rocker gear/springs.

My street SBC with hydraulic roller cam and solid roller lifters runs at 0.012" without issue. I heard horror stories about hydraulic roller lifter quality and failure rates on them, so I went with Isky bushing solid roller lifters when I built it. So far so good 3500 miles (450 HP 383).

my tthinking is any lash reduces gross lift,

quote:

Originally posted by rusty:
my tthinking is any lash reduces gross lift,

Correct. Tighter lash will cause the valve to start opening sooner, open the valve further, and keep it open longer

Sometimes I have a hard time visualizing things. I guess if it was at peak lift and I backed the screw off .005” it has less lift and more lash.

Tighter lash will also bleed off cylinder pressure and slow the car down, been there done that. my small block is Reher-Morrison 427 . The spec. sheet that came with it says .024 hot at 130 degrees. I set them at .022 cold .

My cam card calls for .023 hot. Initially I set them to .017 cold and when I checked hot they were .023. Iron block, aluminum heads. I don’t re-adjust until they check .019 .

What method (eoic) does everyone use to set/ check valve lash??

I have to adjust them cold (the neighbors were complaining about the 3:00 AM warm up). Like most of you, I set them (T&D's) .002 & .003 tighter when It's cold.

Just joking about the 3:00 AM, usually it's 5:00 AM, I'm not THAT inconsiderate. No one ever needs sleep past 5:00.

Bob

quote:

Originally posted by markemark:
What method (eoic) does everyone use to set/ check valve lash??

Yes, the EO/IC method is what I use.
To the OP, if I were you, and I did not plan to pull the cover and cam sprocket to ID the camshaft, I would leave the lash as-is and run it. (Thinking / hoping the previous owner knew what he was doing).

Get it warmed up good and measure valve lash then. That is probably close to where it should be (assuming guy knew how to run his valves.) I think most cams are .028- .030 hot or tight lash about .016-.020 hot.

Steel and aluminum expand at different rates so your cold measurements will vary some but you still want same hot lash.