Roller Rockers benefits 1.675 or 1.725.

[Mix01FLHT]

With big cams, say .585 lift or more, which should you use the 1.675 or the 1.725 rollers?  What are the main advantages or disadvantages of one over the other?

Thanks

[KingofCubes]

More valve lift. Not the perfect way to get more lift but for the street on moderate lift cams it's OK. An example is the R&R615 which came about when R&R was dyno testing their heads with the S&S585 and found that the torque and power went up quite well when they added the 1.725 roller rockers o the intake side only. So Reggie designed that lift into the cam (with a slightly broader nose and softer 3rd polynomial curve) thus the RR615. If you take the RR525 bolt in cam and add the 1.725 intake rockers you will virtually have the Andrews54 (the 525 made more torque and horse than the 54 in testing without the 1.725's).

[Mix01FLHT]

Will the springs need to be changed as well, with say a 600 lift cam? 

[Don D]

I would say the benefits are hit and miss. With most mild generic builds there is no advantage. The characteristics of the heads come into play and in this case if you are using ported heads as the porter for recomendations. They should also be the ones that can suggest the better fit cams for thier heads and avaoid the expense of cam timing changes and high lift rockers.

[Clintster]

Years ago when I ran the SE 211's, Ed suggested trying the greater ratio rockers.  I wonder if it would be something to try on the current builds.

[Don D]

Perhaps. Would depend on the heads that you run and their characteristics. In some cases just a higher lift Intake or Exhaust would be a good move. I don't think this is a 1 size fits all deal. Ask the porter, or if the heads are stock I can give you a better opinion.