Originally Posted by fishman1
Nobody has told me why it is the best way and the way i explained is the wrong way..i am getting opinions is all............i am going to the dyno on friday and i am going to try both ways to see what the diffrence is
Both methods are good, but the exhaust opening/intake closing is more accurate with large duration cams. The reason for not setting both valves at TDC is that the intake is still slightly on the closing ramp of the cam. I have seen as much as .015-.020 extra clearance on the intake with valves set this way and with Hyd. lifters will not center the plunger and not fully pump up resulting in lifter chatter.
The reason for the eo/ic method is it assures that lifter is on the true base circle of the cam and is highly recommended for large lift/duration cams. The reason is as the lift and duration increases the amount of available base circle decreases especially with flat tappet cams as the lifter requires a gentler ramp to keep the lifter off it's edges versus roller cams that don't require as much surface area and can utilize a faster more aggressive ramp and actually increase the amount of available base circle.
If you are going to use the TDC as fishman1 describes use the order for your engine as it needs to follow that particular firing order. If your curious if it is accurate for your cam go back and check with the eo/ic method and log any differences.
Here is a good article I found on this.
http://www.carcraft.com/techarticles...ash/index.html