Timing Chain Tensioner 318/360

I agree that there is only one direction of "pull" on the chain. But timing will vary because if you've turned a few engines by hand you can feel the drag when a spring or springs opposes the valvetrain. Combine that with the crank flexing torsionally (which they all do to an extent) and the steady "pull" isnt steady. At higher roms this can cause the timing to fluxuate and as a chain streches (again, they all do that too) it get's worse. So for me, it's just a way to extend the service life of a timing set and help stabilize the timing for $30.

I'll add as far as drag goes, a rope rear main (also a favorite of mine) adds a ton of drag. the tensioner has none discernable by turning it.