valvetrain · FF-0488

Why is valve lash set so tight on ARDUN heads?

Normally lash is set cold and gets smaller as the parts expand, and Steve gives roughly 12 to 18 thousandths as what he has seen. The ARDUN cam maker specifies 10 thousandths intake and 12 exhaust, which is tight. The reason: the aluminum head is thick and grows as it heats, more than the push rods do, so the lash actually increases as the engine gets warmer. Steve sets his at 10 and 12.

Expert

Steve Coppock

Evidence

expert attributed

Component

valve lash

Applicable scope

Steve Coppock's ARDUN overhead valve Ford Flathead V8 dyno engine