I can tell you this, if Andy had wanted to make it look like the higher ratio rockers made a big difference in power, it would have only required a cam swap.
A slower, lower lift, 24 hr endurance type lobe...... About 20deg shorter, and the results of the rocker swap would have been a lot different.

There's a thread over on speedtalk now about one of the recent EM class winning builds, which used a fast rate short duration cam, along with steep valve seat angles(less low lift flow) and high rocker ratios to get the job done.
Swapping from the 1.3 break in rockers to the 1.85 ratio rockers used for the competition was a 50hp difference at the top end of the curve.
So...... Even on that motor...... How much difference would you expect to see going from 1.5's to 1.6's?

What was interesting about my test is that I inadvertently proved something. I was testing rocker arms and ratios in search of more power. I assumed that more rocker ratio on my engine would make more power. But it didn't which then made me question what was going on.

Basically it all boils down to finding the choke point in the engine. If the valve lift isn't the choke point then adding more lift doesn't add more power. If valve lift is the choke point then more ratio or more lift adds power.

Unfortunately, magazine articles for the past 50 years have skipped over this fact. The typical magazine article goes "we tested mfg X new part and made Y power". Not very many articles like mine get published where the article says "we tested a bunch of stuff and found zippo". Nobody likes those articles even though they prove something.

To be fair the best article would be to do what Dwayne is suggesting. Take my engine and change cams and redo the rocker arm test. That would show everyone exactly what is going on.

I won't claim to "know" exactly why your motor didn't respond to the rocker swap test, but I don't feel it's because of what you described.

The generally accepted "rule of thumb" for changing the RR by .1 is that the motor sees that similarly to adding 5deg of duration.
Many years ago we were doing some testing on a friends 13:1 Pontiac bracket race engine.
It had a solid flat tappet cam that was 263/271-108.
Lift with 1.5's was .556, and with 1.6's .593.
This motor was pretty severely port limited on the intake side and I was pretty sure it was going to really like 1.6's.
We installed 1.6 intake rockers and promptly lost 15hp.
Messed around with timing, lash, jetting...... All to no avail.
Put the 1.5's back on and the 15hp came back.

The next step was to install a roller cam...... Which was 268/276-108, .592 lift with 1.5 rockers.
That made 50hp more than the flat tappet cam, and 65hp more than the flat tappet did with the 1.6 rockers.

What the roller cam could do differently than the solid cam was.....leave the valve closer to the seat at the beginning and end of the lift curve, and still provide more high lift area than the flat tappet, even with the 1.6 rockers.

Changing the RR changes the rate of valve opening/closing, as well as the lift.
Many times the rate is a bigger player in making power than the lift is.

IMO, a more telling test for the lift vs rate would be two cams of very similar specs(lift, duration, lsa), one really fast, one really slow....... See how the rocker ratio differences affect the power between the two.

Never watched it. Who sponsors it, and do they make rocker arms?

Rate of lift is a pretty complex explanation although that could be the case. It would be very difficult for the average guy to figure out how to test that. The cam catalogs don't provide rate of lift as a spec and most shops don't have Cam Doctors.

It might be something that I explore at some point in the future but I have a feeling it would get really messy and complex. Rocker ratio is an easy concept for people to understand even though it isn't the actual answer.

In everyday stuff for most guys actual action at the valve is what matters most, in real specialized aplications like high RPM ragged edge stuff you could probably get a handfull of HP by useing a higher ratio to get that valve action, thats the reason NASCAR engines use very high ratios like 2.0 to 2.2 you have less wasted motion on the lifter/push rod side of the valve but have the same motion at the valve.

On my personal stuff I prefer to run a smaller cam duration with higher ratio as most of it is SB mopar stuff and the higher ratio rocker slightly improves the PR angle mess as well as allowing more lift with out big duration.

I do find it interesting that the way cam specs are often discussed is as if nothing important happens below 0.050" on the lobe. My limited experience suggest that seat timing is meaningful.

I have changed three or four personal motors over to full roller rocker arms. What I noticed was the engines were more responsive to the throttle. Gained revs faster.

I had one motor that I changed over to full roller rockers and one that I changed back from full roller rockers to ductile iron non roller rockers. What I noticed in both instances was my wallet was lighter; that was all.

But those plastic valve covers....

Thanks to Andy and Dwayne for the conversation and sharing real experiences. After reading through it, I feel like what I’ve learned is that adding RR is a crap-shoot.

Dwayne are you saying the roller cam was slower off the seat?

I read long ago according to someone, David Vizard I think, that the reasoning was that not much flow happens below .050 @ the valve. That never made sense either because its given at .050 tappet lift.

It never made sense to me at all that the specs are given at the lobe at all. Valve train and lash play a huge part in what happens at the valve and that's all the engine cares about.

In that instance, way slower.

There were a few factors with that build where it didn't want really fast valve motion off the seat(when the piston is going the wrong way).

Interesting, I've dug around for info about that before but there's not much out there that I could find

When you change something to the engine combo that's counter productive to making power..... It shows right up on the dyno.

Four similar sized cams, three solid roller and one solid flat-tappet. Which one's the SFT?

A. Lift - Duration
.016 - 307 -> SAE duration @ .018" lash (.004" lobe lift above lash)
.020 - 300
.050 - 266
.100 - 232
...

B. Lift - Duration
.016 - 304 -> SAE duration @ .018" lash (.004" lobe lift above lash)
.020 - 297.5
.050 - 266
.100 - 232
...

C. Lobe - Duration
.0145 - 308 -> SAE duration @ .016" lash (.004" lobe lift above lash)
.020 - 295
.050 - 261
.100 - 229
...

D. Lobe - Duration
.0145 - 311 -> SAE duration @ .016" lash (.004" lobe lift above lash)
.020 - 297
.050 - 263
.100 - 231
...

Unless you can do every cam comparison in EXACTLY the same engine build to map the valve-lift profile, there's no valid way to compare valve-lift curves. The best you can do is map the lobe profile and take into account the lash (if any) effect on seat duration, etc.

Those are all pretty close but I'm going to guess cam C.

And yes every engine is different, but every engine is already different. We're just looking at lobe specs, adding another degree of uncertainty and making it more difficult to compare manufacturer to manufacturer. I.E. comparing an SFT with .016 lash to a SFT with .028 lash with the same @ .050 and advertised duration. How similarly do they really run in the same engine?

The roller tappet always follows the point of tangency (closest point) of the lobe, and on opening that's next to it (sideways) rather than below it like a flat tappet. Too much side thrust breaks things.