It really depends on the car and mileage but I'd say every few months. You'll know once you check them. If they are tight after 500 miles then go to a 750, etc. If one valve is overly loose it's an indicator of a problem and can save you a catastrophic failure. I'll be keeping a closer eye on mine. Jason reviewed the photos and it's going back together this week. I have a race next Sunday so I'll be out in the garage a few nights this week.
