|
A more simple but slower and the most accurate method on I4 & I6 donkeys is the 'opposites' method: Watch the rockers move when you rotate the crank, when inlet valve 1 is at full lift, inlet 6 is the opposite and exactly at it's lowest point on the lobe, now adjust it. This method is more time consuming, but you get to see how much lift each lobe has.
A lot of B18, B20 & B30 engines have a cam which has partially failed to break in, but running fine. Sometimes you will see a valve only has 1/2 to 2/3 lift, visually. If you have 6 intakes with full lift, but 1 or 2 exhausts with only 1/2 the expected lift, don't worry about it, because you aren't missing much. If an inlet is missing a little lift, you start to loose a few horses. Either way it has likely been that way since the cam was first broken in. Exhaust lift maters a lot less because the high lift flow is very poor relative to the inlet.
With the exception of using a stock K cam, I choose lower & slower lift lobes for the exhaust because it doesn't need the lift + it has a tougher time opening. When the inlet opens, it opens against spring pressure only. The exhaust has to open against spring pressure + residual cylinder pressure which is holding the valve shut and is greater than the spring pressure! I waffle on....
|
