Valve clearance change

[sierra4000]

Hello,
What is valve clearance change for different engine temperatures ?
That change is linear course during engine warm-up?
Is a 16 valve DOHC engine with solid flat lifters and aluminium head.

Thanks for your posts

Radek

 

[BrianPetersen]

It will be different for every different engine design and the best thing is experience with your specific engine with your specific tuning.

Most bucket-and-shim DOHC designs tighten up on the exhaust valve as the engine runs (and this is why cold-engine valve clearance is usually specified higher on the exhaust side), but the dominant effect is the exhaust temperature and therefore the exhaust valve stem temperature, not the coolant temperature. Whether the higher thermal expansion coefficient of aluminum will "win" over the greater temperature difference between the exhaust valve and ambient compared to the cylinder head and ambient ... is anybody's guess and will depend on a million factors, including how much load (heat) you are putting on the engine.

What's wrong with setting the clearances to what the engine manufacturer recommends, and calling it good enough?

 

[sierra4000]

Thank You Brian!