What are the benefits of going to a 1.6 or 1.7 rocker ratio versus just getting the correct cam to start with. Is there some sort of mechanical advantage with a higher ratio rocker?
It seems that hardly anyone runs a 1.5 rocker anymore judging from some of the builds I've seen here.

Gus

Never mind

The higher rocker arm ratio gets the valve off the seat faster. (higher acceleration for the valve)

The question is do you need to get the valve off the seat faster for your build? If you don't then there isn't any point in the higher rocker ratio. You'll just be beating on the parts harder without making more power.

Most of the builds on here do not need a high ratio rocker arm but there isn't necessarily anything wrong with using them as long as they matched with the correct cam. A typical Mopar bracket type big block engine can easily make 600 or 700 hp with the factory style 1.50 shaft rocker arm setup.

If you're looking for 1000 hp then you'll most likely need to ditch the shaft rockers and use a higher ratio.

The only way to know for sure if you could use
a bigger ratio is to test it by tightening
the intake lash some.. I run a tighter lash
on my engines.. thats cheaper than buying new
intake rockers.. I have never seen the engine
make more power changing the exhaust ratio
unless its WAY off

I see this consistently from guys that have a lot of experience, so I trust it to be true. But it begs the question: why does every split pattern cam I’ve ever looked at feature more lift and duration on the exhaust side of the equation?

I’m planning on going from my current 1.5 to 1.6 rockers this winter for the following reason: last year I had my heads ported and prepped, and the flow sheet says they continue offering more flow well past .650 lift while my current cam offers net .555 lift. My theory is that in my case more lift and effective ramp speed should benefit me (??). The rest of the combo (carb/intake/exhaust) should also adequately support more flow. Hopefully we’ll see if I’m correct.

My W-9 heads were known for having good exhaust flow and
I had the rockers to change over so I did.. the car didnt
show any change with just the exhaust.. all I can say is
test it and see

First, most split pattern cams I have used may have more exhaust duration than intake, but always have less lift. Second, if your heads can handle more flow than what you are creating now, than a 1.6 rocker will help. Higher ratio rockers not only give you more lift, they also give you more duration at valve, without creating more motion from lifter or pushrod. Most "Other" brand engines, and even later Magnum engines all use ratios higher than 1.5 these days on production engines. So there is something to be said for higher ratios. My last 500 cid build had Indy -1's with Jesel 1.7 rockers. The cam I chose was based on a BBC grind, that also used factory 1.7 rocker ratio.

I spent a bunch of time and money last year testing rocker arm ratios. The answer is that your engine only needs what it needs. Adding more rocker arm ratio or more duration to the cam doesn't add any power if the engine doesn't need it.

Based on my testing I'm pretty confident that a person can build a 700 or 800 hp BB Mopar with 1.50 shaft mount rocker arms and cam lobes right out of the catalog.

https://www.hotrod.com/articles/trying-find-extra-power-rocker-arm-testing/

This is definitely one of those “ it depends” items.

My flat tappet cam lobes are worn and I'm replacing the cam with a hydraulic roller. There aren't many off the shelf grinds available and before I either get one custom ground or buy off the shelf I wan't to know if I should add new rockers to the build. My current rockers are some good old 1.5 Isky's with the premium service from RAS. They are working perfect on my old cam but will they be good with my new cam?
My combo
493 10.9 compression Wiseco Pro-Tru flattops
Indy EZ heads std. port with some clean-up and valve job by Nick Wilson. They flow 319 at 600.
My car is a street/strip deal that runs 10.91 124.6 at 3640#
I wouldn't mind a 10.50 time slip in my glovebox. I think I can get more out of my combo with just a valvetrain change.
My old cam was a Comp XTQ series 292-312 grind.

Thanks
Gus

If you liked how it ran with that 292/312 flat tappet then you could swap in a XR292HR-10 hyd roller and it should be close. If it was me I'd probably go down one size on the cam for street driving and use the XR286HR-10 but it really depends on how you drive the car as well as gears and weight and how well the carb is dialed in.

For street cars we've been using the XR280HR cam in the 500 inch stroker engines. That cam is a little small for drag racing, but it sure makes them run nice on the street. 600+ ft-lbs of torque down low and they'll still make 550 hp at peak. In your case you might want a little more top end power for drag racing.

I think your existing rocker arms will be just fine with a hyd roller cam.

IMO, your rockers are fine for what you’re looking to do.

Hyd roller vs solid flat tappet for an ET improvement?
I guess we’ll see how that works out for you.

I am not saying to run a hydro roller, BUT, I went from a solid FT to one in my 512, used one from Hughes, 9.7to one, 4050lb street car,
solid cam was 248@.050 116 mph 12.03 2200 DA
Hyd roller 255,258 @ .050 121 11.33 mph 1750 DA Short shifting 5500, easy pass
but I used the expensive High RPM Morel.
Still need to do some track tuning.
also had better rear tires for the faster pass

Your Rockers are great, BUT I also went from 1.5, to 1.6, not saying it had anything to do with more power

Well I wish I didn't have to do this deal at all but my old cam gave up after about 5 years and I don't want to go flat again.
I checked on Morel rollers and they were over a grand and that's just a little much for my build budget.
I'm probably going with a Howards cam and lifters they have better reviews than Comp Cams do.

Gus

Morel has 2 versions, I think the Howards are the less cost Morel from what I have been told

Check with Gaterman for pricing. They have really nice looking hyd roller lifters.

Considering the RT weight, it would be nice to fit a 3/4" pushrod in there for the extra spring load...

Maybe I am just too old school, but I don't see the advantage of going HR versus FT solid cam. A solid cam may be a tic noiser, but a few thou tighter on lash helps. plus they are cheaper by a bunch, and allow you to see any problem early on in the valvetrain. Valve lash changed a bit? OK, what caused that? Something is wearing. Easy to find. HR adds two areas for failure; the roller wheels, and the hydraulics.

I agreed with everything you just said, until the tool steel solid FT lifters started eating up my camshaft lobes & I had to go back through the engine, I just hope the hydro roller holds up, so far over 2k miles & all is good.