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tinman

Do Roller Rocker Arms Add Horsepower?

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Meh, the very first time I switched from stock Cleveland rockers to roller rockers (Crane Gold) had nothing to do with hoping to gain more power. It had everything to do with stopping the excessive bronze valve guide wear I was seeing after switching from a rotating mulit-groove valve/retainer/lock assembly to a non-rotating single groove valve/retainer/lock setup.

The stock setup's direct side-pull/friction at the stock rocker tip-to-valve tip contact point obviously increases a bunch if a multi-groove rotating valve/retainer/lock isn't in the system. But swap the stock rockers for the full roller rockers and the problem was instantly solved & the bronze guide wear completely disappeared.

 

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Yea, leaving the unanswered question just hanging there of 3/8 rocker stud flex vs crap rocker causing the power drop was a stupid move IMO. All they had to do after the 3/8 stud/"roller tip only" rocker dyno pull was make the very next pull be one with a stud girdle installed just to see what happens before moving on to the dyno pulls with the full roller rockers.

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that was my take before the vid was over, that the test is way incomplete and brought up more questions

back to back 3/8" vs 7/16" studs, then with girdle

where do bushing rockers land?

bolt down pedestal roller Scorpion / Yella Terra etc?

do conventional girdles recover the power AND show an increase?

and i just thought how bout the Motorsport girdle covers, do they recover the lost power AND show an increase?

more, less or similar power loss with solid flat tappet lifters and spring rates?

where they left it what i got is; pay for studs, machining, guide plates, rockers and locks to lose power

that's sure not what we've been fed all these years :rolleyes:

 

where's Steve, still wondering at what point are girdles necessary?

 

 

 

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At first my "drag racing only" brain response was going to be "if it needs a stud mounted full roller rocker, then it always needs a rocker stud girdle". But after thinking about it a little the actual need for a rocker stud girdle really does kinda depend on the engine's intended use.

(A) High RPM use and/or high spring pressures?.....of course, slap that sucker on there.

(B) Lower RPM use and/or lower spring pressures?.......not usually needed. But hey if someone still want's to use one it's fine, sometimes overkill is a fun thing.

(C) Smaller OD rocker studs (like 3/8)?........meh using a bigger 7/16" stud is a better way to go. But if 3/8 is the only option, and if it might see some RPM's, then why not use a stud girdle just to be safe. On the other hand TBH I don't really know if a stud girdle for 3/8 rocker studs even exists, (because I never had to worry about 3/8 studs, my Cleveland stuff always had 7/16).

 

The thing that always made me a fan of rocker stud girdles was the valve lash adjustment staying dead-nuts perfect every pass vs moving all around pass to pass without one.

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I've been lurking on sidelines guys taking in info. By looks of it thats why no issues with the Cleveland with the big 7/16 stud and rocker before. Quite stable. Most times my spring pressure never went north of 400lbs open. So must be the threshold. I've definitely run lots of c motors with no girdle well past 7000

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6 hours ago, steve.k said:

I've been lurking on sidelines guys taking in info. By looks of it thats why no issues with the Cleveland with the big 7/16 stud and rocker before. Quite stable. Most times my spring pressure never went north of 400lbs open. So must be the threshold. I've definitely run lots of c motors with no girdle well past 7000

i didn't hear them state spring pressure in the vid at all but 7/16" stud roller rocker still lost power to the stamped steel rocker, just not as early as the 3/8" stud. they're attributing it to the additional weight of the rocker causing spring issues along with possible stud flex. if it's either and/or both NET LOSS

Dave i don't think the girdle cares what the studs are, just the lock OD?

3/8" studs with a girdle better than 7/16" w/o? 

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11 hours ago, tinman said:

Dave i don't think the girdle cares what the studs are, just the lock OD?

My fault, I typed stud girdle but meant the long/tall poly-locks for the stud girdles. I honestly don't know if the long/tall poly-locks are available with a 3/8 thread (never needed the 3/8 stuff so I never looked).

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12 hours ago, tinman said:

3/8" studs with a girdle better than 7/16" w/o?

IMO rocker stud girdles always have the advantage. That's because at that exact point when any single rocker stud by it's self is coming under a flexing/bending load, it is also being supported by all the other rocker studs it's tied/bridged to.

Heh, too bad the same thing can't be said for the crap bolt-on main cap girdles since main caps don't "sway back & forth like a tree in the breeze" like rocker studs do under load.

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