Mancini/HS 1.6 rocker not giving me the lift expected

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Looks like the Hughes rockers in post #20 may have labeled a 1.5 ratio rocker as a 1.6 ratio rocker. You can see the rocker on the left has the adjuster more forward than the adjuster on the right. To get the 1.6 ratio, the adjuster is moved closer to the center of the shaft.

Either way, quality control from their rocker supplier or parts marking team if marked by Hughes themselves is lacking.
 
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Rocket said:
Looks like they may have labeled a 1.5 ratio rocker as a 1.6 ratio rocker.
Either way, quality control from their rocker supplier or parts marking team if marked by Hughes themselves.
Click to expand...

This is from the Harlan Sharp site that makes distinguishing their ratio a bit easier. These of course are their roller rockers.

IMG_4171.png
 
You lose , typically, .020 IF the rocker pattern is centered or real close.
No. 3 and 4 exh push rods might have sode angle as well, check.. they lose a lil more.

Last one that was like the above example .575...net was .550
 
Crane made quick lift rockers for Chebbies. Overall ratio didn't change, but these rockers lifted the valves off the seat more quickly. Crane did that by lowering & moving the p'rod cup in the rocker.
 
Spadman said:
I installed an MP 2992 nos cam advertised to be .474 lift. Went with Mancini rocker kit 1.6 ratio. The box arrived marked 1.6 and they are grey as expected. I put washers in a hyd lifter for checking and get only .465 lift. The lift directly on the cam lobe is .317, as expected. I have a ball and cup checking pushrod in place with heavy springs so could have a slight amount of flex. Mancini says call Hughes. What could be the problem other than wrong ratio rocker.
Click to expand...
.317" × 1.5 = .475"
.417" × 1.6 = .504"
Looks like you have 1.5:1 rockers and flex from the heavy springs.
Does Hughes supply the MP cam? I can not see it as a cam issue if your measured lift at the lifter is the advertised .317". These days mis labeling or packaging is a growing problem, then they try to pass the buck.
 
Dale Davies said:
.317" × 1.5 = .475"
.417" × 1.6 = .504"
Looks like you have 1.5:1 rockers and flex from the heavy springs.
Does Hughes supply the MP cam? I can not see it as a cam issue if your measured lift at the lifter is the advertised .317". These days mis labeling or packaging is a growing problem, then they try to pass the buck.
Click to expand...
You have a typo; says.417 in second line when you meant to repeat .317. No, the cam is not from Hughes; I got it from a Direct Connection dealer in the 1970’s; just haven’t run it yet. The rocker dimensions check out when I talked to a Harlan Sharp tech. I’m certain now the problem was trying to check the lift with a checking pushrod and strong springs. I looked back at some older notes and with the checking spring I got the full expected lift with the longest possible pushrod length.
 
Sorry guys; I said in the original post that the Mancini tech told me to call Hughes. That was not correct. He told me to call Harlan Sharp that made them for Mancini. The Harlan Sharp tech was very nice and gave me the specs on the rocker that allowed me to confirm it was a 1.6. He suggested the discrepancy was due to the checking pushrod flexing as I had suspected. Cam is good. Rockers are good. I just need to get my pushrods cut now that I have the best length. No problem with Mancini or Harlan Sharp. I’ve never done anything with Hughes.
 
Hughes ain't bad. They catch a bunch of grief because they don't give customers the reach around with lube when they call. But they do try to help, but you gotta realize they're in the business if making valvetrain parts. An a lot of guys out there take shortcuts and don't check things they should. Or worse yet knowingly run stuff that is set up wrong.
 
It was a 400 Pontiac engine. I didn't mention that because the rocker action is the same whether stud mount or shaft mount.
 
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