So, as part of my refresh, I decided to replace my ancient Crane Golds. After some consideration, including the premise that they're made in the USA, I purchased a set of PRW rockers. In the end, this also necessitated a switch to new beehive springs. Now the engines all assembled and ready to bolt up to the trans and drop in. Just for the heck of it I put the dial indicator on the head tonight and measured up my actual valve lift. I'm at .513" net valve lift on a .575" roller, at .020" lash. With 1.6 rockers.
Wonderful.

That doesn't surprise me. I also wouldn't recommend PRW rockers with a solid roller cam. Unfortunately, high quality rocker arms are now super expensive. Even the middle of the road stuff has become really expensive.

Something is definitely not right. Your .575" roller is a .383" lobe lift (.575 / 1.5). If you take your measured lift of .513" and add .020" lash this gives you .533" gross lift. Divide that by the lobe lift (.383") and you get your actual rocker arm ratio - which is only 1.39 instead of 1.6

How's your geometry?

Just a thought ... with the 1.6 rockers your total lift should be around .608. This is "roughly" .100 more than the .513 you claim. Could you have read the dial indicator wrong ... .513 instead of .613 ???

measuring lift at the valve requires the dial indicator set-up/readings to be different than measuring a cam lobe. i think with that kind of difference there probably is a set-up/reading error. go back and re-think what you're doing. i think with that kind of lift you need a 1" indicator zeroed at .700" depressed.

I just recently had a builder verify the net lift at the valve was going to be under .700” for this particular build.
He checked two rockers, the theoretical lift would have been .690.
One was like .650, the other .665. The lobe lifts were .460” for both.
PRW steel 1.5 rockers.
This was on a BB. If you’re working with a SB and the stock 59* lifter bank angle, that alone will cost you about .05 worth of effective ratio.

I did double check my measurement. I measured the valve travel in both directions, by zeroing the indicator at both fully open and fully closed. Then I took my dial calipers and measured installed height and fully open height. Same thing. With my old Cranes, my actual net valve lift was better than .580", with the same lash.

The Cranes I have checked were always higher than the advertised ratio.

Also, if you’re using a shaft relocation kit for geometry improvement, I’ve seen instances where they have resulted in a lower effective rocker ratio.

And any deflection.

I’m saying that when the lift was checked with and without the relocation kit, there have been instances where the addition of the kit lowered the effective ratio.

So, if the OP has one of those kits installed, he could remove it and see if, in his particular situation, it has any impact on the ratio.

The highest departure from the “advertised” ratio I recall seeing was 1.67 from a set of HS 1.6’s on some Indy SR’s using checking springs.
With the full spring force(700lbs) at .700” lift, the effective ratio was still 1.63.

Edit- re-read the OP.
I didn’t see where it said if the lifters were solid or hyd.
You can’t get a good read on the true running lift using a hyd lifter for mock ups(it compresses)......... if that’s what you’re doing.

Solid roller, and no shaft relocation.

Did you measure lift at the cam lobe? I bought a Lunati roller that was supposed to be .600 lift but was actually a smaller cam - despite all the correct numbers stamped on the cam. Being in Canada, I had a hell of a time getting it replaced by Lunati and it was all at my expense !!

Can you post a photo of one of the rockers? Top and side view if possible.

Here's the thing with Mopar rockers, the length from the fulcrum to the contact point on the valve should be fairly close on any rocker - that length is fixed by the head design so its not something a manufacturer can vary by much.

So to vary the ratio the manufacturers move the pushrod location. To increase the ratio the pushrod is moved closer to the shaft. This is easily visible from 1.5 to 1.6.

Let's have a look !!

It should be....... but in reality, there are definitely length differences on the valve side between the different brands.
Stealing a pic from Andy’s book:

And:

Sounds like you just have to decide how badly you want that ratio to be closer to “correct”.

Yeah there were all these arguments on the forums years ago so I went and bought one rocker from each mfg and put them all on a shaft. Once I did that I said "okay, now I get it"!

The Mopar rocker arms are all over the map. You don't know what works until you try it. Eventually I created a little cheat sheet that told me which rocker arms worked with which cylinder heads. If a person just randomly selects a rocker arm package then good luck and may the force be with you. Not everything works on everything.

Well the Cranes definitely look like they'd have issues. Everything else being equal, they would have less lift at the valve than any of the others.

I have Harland Sharps on a set of Indy EZ's. The lift at the valve is pretty damn close to where it should be for a 1.5 rocker.

Have you shared this cheatsheet ?

I’ve used the Crane golds on stock heads, stage 6’s, Indy SR’s, Indy EZ’s, B1/BS, and RPM’s........no problems with the fit that were serious enough for them not to be used.

Plus...... they were pretty affordable too.

My go to replacement for them are the Mancini rockers, but I haven’t had the opportunity to test fit them on all of those applications.

The solid spacers between the rockers that the Mancini rockers use aren’t as universally install friendly as the springs that came with the Cranes.

I really hate to sound obtuse but I fail to see how a 'geometry correcction kit' can have a ratio effect (change) on a set of rockerarms. Regardless of the rocker ratio itself, all a 'correction kit' does is move the position of the rocker arm contact to achieve proper scrub angle...does it not? So, how then does THIS change the actual ratio or effective valve lift/ratio?