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I understand that there are many variable that dictate how much a pushrod will deflect such as overall length, width, wall thickness, valve spring pressure, valve train component weight, RPM of the engine, heat treatment, and construction material of the pushrod; but is there a general number to use for factoring actual valve lift when teh engine is operating? I know its complicated to say based on so many variables, but is it safe to say that a pushrod will deflect .020" regardless of all these variables? .030", .040". Lets say a 3/8 pushrod with a .080" wall thickness with an overall length of 7.75". Would it be safe to say at 650 pounds of open spring pressure that the pushrod will deflect a minimum of .020??....Or what as a minimum. Im not asking for absolutes, basically what as a minimum could be expected.



Lot depends on the cam ramp. roller with 260-280 @ 50 with 650 over the nose your on seat is around 260-270. You don't want to use the block or head for A guide. If you can run 3/8 rods that's A plus and make them .120 wall. with the new cam profiles you need wall thickness to keep the p rod from acting like A leaf spring storing energy and unloading on the closing side of the lobe and bouncing the lifter off the cam at the base. I have been there