Adjusting Valves Question

[70sixpkrt]

When adjusting valves, is it better to do it hot or cold? I am running Edelbrock Aluminum heads. My cam is a Scott Brown solid. The cam card says Hot .018 and .020. If I do it cold, how much tighter should I go? Any disadvantages of adjusting it cold?

[justcruisin]

Setting cold with an iron block and aluminum heads I subtract 0.006" then readjust hot. But if it is a running engine you should just heat it up with a good run and set them hot.

[alfaitalia]

You can take the "hot" setting given to you in your cam manufacturer's catalog or cam specification card and alter it by the following amount to get a "cold" lash setting:

• Iron Block Iron Heads –  Add  .002?

• Iron Block Aluminum Heads – Subtract  .006?

• Aluminum Block Aluminum Heads – Subtract  .012?

Remember this correction adjustment is approximate and is only meant to get you close for the initial start up of the engine. After the engine is warmed up to its proper operating temperature range, you must go back and reset all the valves to the proper "hot" valve lash settings.

Source: Crane cams

EDIT....beaten to it whilst typing!

[Brass]

Maybe set them hot first and then go back and check to see what that same setting is cold.  I think that would give you a cold number to set them to in the future. 

[70sixpkrt]

I kind of would like to do it cold. I hate playing with hot valve covers.

[c00nhunterjoe]

.005 change for cold lash, alum heads, iron block.

[justcruisin]

You can do it cold and forget about any hot adjustment if you want but the thing is they need to be set correctly when the engine is operating at normal temp, when your driving the engine ain't cold. If you set them as instructed cold and then check one set hot, chances are the rest will be the same, if you don't like doing it hot.

[c00nhunterjoe]

Doing it hot can be tricky as by the time you get half way through, the temp has changed and they will be inaccurately set. I have always set them stone cold. They will be even this way. You can recheck them all quickly hot to double check the spec, but set them cold and account for expansion with your lash setting.

[BSB67]

In your case, subtract 0.006" from hot lash spec when setting cold.  That will be way way close enough and good enough.  I see manufacturers lash recommendation as just that, recommendation.  It's not a life or death number.

[c00nhunterjoe]

Indeed, the numbers are a reference point. Your engine may light a little more, or a little less, depending on the cam specs vs your combo and head flow.