Originally Posted by dkveuro

In the interests of chain longevity, it depends on the load the chain sees.

On a 2 valve per cylinder I4 motor, the cam lobe ramp feed back is heavy and loads of 70,000 lbs shock the chain at high rpm's.

On a 2 valve I5 or I6 motor, the ramp load feed back is nearly all cancelled out due to an opening ramp is being opposed by a closing ramp.

This is why the early simplex chain on the 380's was so short lived as it was in effect doing double duty in that it was running two seperate 2 valve I4 cams.

Next time you get a chance....use a wrench to turn an assembled cam in a head on a I4 motor...and then try a I5 or I6 motor.

Vous comprenez ?

.
.