It's Greek to me...

freshly honed and will do. One is 040 and other is 060. Have new KB pistons for the 060 and bearings.

Good post. Gonna get back to this one tomorrow.

The rocker ratio increase can definitely affect whats going on duration wise at the valve.

Ill see what the cam software can do with that topic later. If i recall, altering the rocker ratio, will simply adjust the cams design. Generally, I think the cam software , and most cam grinders, will design a cam , based on the components used. Meaning, that if the rocker ratio is low, it will add some lobe area, if its high, it will remove some.

Then there is the lash thing. It kinda relates to rocker ratio. Changing lash, changes whats going on at the valve, like ratio does. Your solid roller camshaft, would have "lash ramps" built into the cam lobe. If i recall, jim runs a hydraulic cam, with solid lifters. I am not sure how that affects things.

Textbook says, running a cam designed for a 1.7 rocker, with 1.8 rockers, adds stress to the valvetrain. Textbook says, running a solid on a hydraulic profile, can add stress to the valvetrain.

But, thats textbook, and at what point in the real world, do those things become an issue. I know some who have done it without issues. Then again, i had a friend running solids on a hydraulic, and over time, the it beat the valvetrain up till it busted rocker hardware and ended up puking a head gasket as a result. Those were in a 38 cigarette that got run for extended periods of time. He has since went to hydraulic roller lifters on the hyd roller cam, and has no issues.

It would be interesting to see the changes, I talked to a cam "guy" that i feel knows "enough" about his field that I consider what he says and then decide for myself. we talked about this very subject over the holidays and on a 236/244 .366 lobe he thought a 1.8 rocker would add 1 degree to 1.5 degrees efective duration to that Hyd roller cam. FYI no real facts to back it up.. lets see what Joe's program says. I'm giving it serious thought to assist my forced induction engines to digest more intake charge, with out cam and lifter changes. still on the fence..LOL

Im trying to understand how rocker ratio effects duration. The cam controls everything. The beginning of valve lift starts at "x" and ends at "y". Everything after the cam is simply a reaction to what the cam does. On the case of a 1.8 ratio arm, it amplifies lift over a 1.7, but it is still the same cam lobe which begins to lift at X. It will lift at a faster rate for more lift but it will begin lift at the same time whether the rocker ratio 1.1 or 1.9. The cam pushes. nothing cam happen until the cam pushes, nothing can happen when the cam doesnt push. Duration is the amount of time that the cam is pushing, It doesnt care what its pushing.

Where am I off track?

Cam/lifter duration is one thing. This is what we normally talk about.

Effective duration is what the valve does. Seat to seat stays the same...but the duration at lift points change a little.

So, how it is discussed does add to some confusion.

i am sure i will get slammed for this but i agree,changing rocker arm ratio can not physically change duration,can only change lift.if someone can explain how this is wrong i am all ears.

That I can understand.. with increased ratio the valve is moving faster and traveling further so it would spend less time at each spot of lift

It does alter effective duration , almost like how a bigger wheel diameter on a lifter does. Of course it doesnt change the duration that is ground into the camshaft.