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Excerpt from Bret Powell's post on setting valve lash with big camshafts:
Adjust the intake when the exhaust starts to open.
Adjust the exhaust when the intake is almost closed...not when it starts to close.
The curved blue arrow is illustrating the direction of engine rotation (when facing the front of your engine after opening the hood). This is also the direction you'll be turning the engine's crankshaft when going through the valve adjustment sequence.Tore said:On the top Valve Lash Adj. Chart by D.Davis I see an arrow that points clockwise, when you look at the rotor spin in the dist it spins C. Clockwise is this correct?
Would't the valve adjustment procedure change when using a performance camshaft?Danny Cabral said:![]()
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Excerpt from Bret Powell's post on setting valve lash with big camshafts:
Adjust the intake when the exhaust starts to open.
Adjust the exhaust when the intake is almost closed...not when it starts to close.
No. (Unless you've done the '2-8' firing order swap, which is only for high output race users who wouldn't use this method for adjusting valves anyway.)jrocco said:Would't the valve adjustment procedure change when using a performance camshaft?
No. The valve is still closed on the base circle (bottom of a lobe, as you said) of each lobe.jrocco said:Wouldn't changes in the duration and intake centerline affect which valves are at the bottom of the lobe?
Wrong! What size camshaft are you using?jrocco said:The charts above work for a factory stock cam. Once you install a performance cam you can disregard that information.
This is because the performance cam will have a different duration and different intake centerline that affects which valves are open at a certain point.
Just to point out that whether the crank is rotated to "0" or "350" or "10" degrees the cam will still be on the base circle because the number of degrees of crank rotation from TDC (on compression stroke) is much more than 4 degrees. In other words when the engine is at TDC the valves don't start to move with just 4 degrees of crank movement. The base circle is from #9 to #6 on the profile drawing (actually a little more).Hi Danny
It only makes sense (to me at least) that the cam grind and how the cam is degreed on installation will affect when the valves are on the base circle of the cam as compared to the 0 reference point on the balancer.
If the cam is installed 4 degrees advanced or retarded, would not the base of the cam be 4 degrees off when the balancer is on 0?
Refering to the Car Domain chart, when you set the balancer on 0 and adjust No 1 intake, No 1 exhaust, No 7 Intake, etc, on a cam that is installed 4 degrees advanced you are not on the lowest point of the cam.
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Excerpt from Bret Powell's post on setting valve lash with big camshafts:
Adjust the intake when the exhaust starts to open.
Adjust the exhaust when the intake is almost closed...not when it starts to close.