Rocker Question

[MO Predator Racer]

What is better to run? A 275 cam with 1 to 3 ratio rockers or a 356 cam with 1 to 1 ratio rockers? They have the same combined lift. Which one is better?
Just wondering because I was just lookin around at parts today.

 

[95 shaw]

A look at duration would be in order.

Though the total lift may be the same, the timing of the lift as well as ramp speeds must be noted against springs and valve lengths to control valves at required rpm levels.

Lots more to consider than just total lift.

 

[Landon Engine Building]

As stated above there’s much more to consider than just lift, I am of the opinion that a low to moderate lift cam with ratio rockers is better due to more aggressive ramps. also what 275 cam are you referring to?

 

[MO Predator Racer]

I was just wondering about how it would do. I was just refering to normal 275 cam not the F275. Say both cams have same duration but different lift but the combined lift with the rockers is the same. What would be better then or is that a dumb question. Iw as just wondering if both cams have same duration and you ran ratio rockers with smaller cam vs non ratio with big cam but both final lift is same which is better.

 

[Landon Engine Building]

Like I said I’m under the impression that smaller lift cams with ratio rockers preform better because of their aggressive ramps. There is a post here on Bob’s that touches on a similar question, ARC also has a video on this subject.

Bob’s forum post: https://4cycle.com/karting/threads/ratio-rockers-stock-cam.120825/#post-862389

ARC video:

 

[knighty]

You need to be looking at the overlap......overlap is king......thats why the 265 cam is so good.