Method for Determining Duration
Thread Starter
Joined: Nov 2007
Posts: 413
Likes: 0
From: Albuquerque, New Mexico
Method for Determining Duration I'm changing my rocker arm ratio and am familiar with the mathematical method to figure lift but I want to know how duration will change. Is there a method for figuring duration that will get me in the ball park?
Duration (at the valve itself) is most definitely affected by rocker ratio changes however its fairly minor. Seat to seat timing stays the same but you get "more area under the curve" i.e. more duration at @ a given lift (.050", .100", .150", etc.)
Thread Starter
Joined: Nov 2007
Posts: 413
Likes: 0
From: Albuquerque, New Mexico
Thanks everyone. I knew that the duration change was only minor but it's looking like a degree wheel is the only way to get it accurate. The cam is a Corvette LS1 #0968 cam. I picked up a surprisingly good deal on a new Comp Cams Pro Magnum kit with the 1.85 ratio. I thought using the cam and the rocker kit for a 5.3 truck would give it a nice boost. I think the reason I picked it up so reasonably is the 1.85 ratio is really too much of a lift change for most modern LSx cams. Performance cams are built now days with so much ramp speed that changing to a 1.85 ratio would cause all sorts of valve train havic I would guess.
