I would think a street car would see more timing changes with the dual idler, because of all the back and forth movement of the throttle. Race is more wide open. The dual idlers on this moved I "BET" a good 5 or more degrees. We caint have all that.
Exactly. And think about those of us with two *&$$@ that drag race clutch cars. Every time you uncouple the engine from the drivetrain you get the timing chain unloading the tension side to the slack side.
It‘s tough on parts and causes the need for more piston to valve clearance. I can run whatever my piston to head clearance is on the intake valve (Ive run as close as .050 on aluminum rods and .040 with steel rods) and .080 on the exhaust and not hit.
There are some (myself included) who think that you have a significant flow loss (and power loss) when piston to valve clearance gets excessive.
Think of the pressure loss under the valve when the valve is too far from the piston at overlap.
