[Fot] Roller Rockers on TR6

[Jack W. Drews]

Roller rockers are subject to a lot of debate, aren't they? I've not 
seen actual dyno numbers that are meaningful, but I'd like to.

My two cents is based on flow bench readings.

What I have seen is that flow increases with valve lift at an 
expected rate until you get to between .500 and .600 lift. The heads 
I've done maxed out on flow at between those two numbers, with only 
3  to 4 cfm increase in flow when increasing it above .500 lift. It 
appears that the rest of the intake tract, namely port shape and 
valve size, reach their limits before valve lift becomes limiting.

It's a different story if you compare flow rates of solid vs. roller 
rockers on a stock cam. In that situation, the max lift on a stock 
cam is much lower so roller rockers give more of an advantage.