Why use Roller Rockers?
Advantages of roller rockers over your standard rockers are less reciprocating weight in the valve train which unleashes power and allows your engine to rev up more easily. When you replace your camshaft with a performance grind you have faster valve opening and closing rates along with higher lift to open the valve further, this alone requires better [stiffer] valve springs to make the cam follower or lifter, follow the camshaft and not jump and bounce. Lighter valve train components like Roller Rockers allow the valve trains combined mass to respond better to the direction changes in movement and take stress out of the valve train.
 
Because of their clever design roller rockers give positive up and down pushing motion in one plane and are not trying to roll off the top of the valve stem in a sideways motion as the valve opens under full spring compression. The roller tip on the valve stops the rocker arm dragging, pushing and pulling across the top of the valve like a standard OEM rocker does which takes side loads off the valve stem as it moves up and down in the head. This lowers friction in the valve train, reduces heat and it makes your valves and valve guides last a lot longer than they would have with the original OEM rocker arms and faster opening and closing valve events with the performance cam.
 
 
Standard rockers with increased valve spring rates are renowned for rolling off to the side on their fulcrum under full valve spring compression [known as rocker arm deflection] and pushing or bouncing on the valve spring retainer. The worst case of this can lead to the retainers being pushed down so that the collets fall out, which means the valve is no longer held up by the spring and it falls into the cylinder where the piston tries to compress it.
 
No ….. valves do not compress, if you are lucky they just bend but most times they break and the piston shatters ~ explodes, puts the rod through the block and piston bits get spat up into the inlet manifold and get sucked down into the other cylinders as it turns over that last revolution or so and seizes ……….. now your block is completely stuffed, crank bent and heads are most likely cracked too from the piston trying to compress lumps of broken steel bits into them. As you might have guess by now it has happened to me ……… completely stuffed a brand new reconditioned engine and I was not giving it a boot full either, my wife was just putting home from work in peak hour traffic when it let go……………
 
 
While talking about defection these forces on the rocker arm are amplified greatly, particularly on full compression with double and triple valve springs that are typically used on high revving engines with high lifts camshafts of over 0.530 lift and up. Stud girdles spread this load across all the rocker arm studs, because at any one time only one or two valves are under full compression, it stops defection of the stud. You will find stud girdles on most Dragsters engines with camshaft lifts up in the 600 plus range and pulling serious rpm on the track.
 
The Yella Terra twin shaft rockers share the load of valve spring compression across two studs instead of one, so as to eliminate any deflection of the one rocker arm stud under full load of the compressed valve spring. Might be good to think of how good a job these components do as you side shift the clutch or release the trans brake on your next launch or when you are down shifting as you slam through the gears trying to pull the car up and into the next turn.
 
The other tendencies of standard rocker arms, especially the cast iron and fulcrum ones like for example on the Ford Windsor and small block Chev is that even with one step up from standard in a stiffer valve spring the bottom of the rocker arm breaks and falls out ……… been there had that happed too ……… This can happen on as little as a commonly installed and popular street set up being the LT1 Chevy valve spring with inner dampener of a typical rate of 90 to 100lbs closed set pressure, which is fairly tame and typical for a mild performance ground camshaft.
 
Pressed steel rocker arms like on the Ford Cleveland V8 and Ford crossflow six cylinders in performance applications can crack, split and wear like crazy …………… especially the OEM alloy fulcrums …. that stuff gets all through out the engine.

OK I here some of you saying now……” but I have run stock valve train components and have not had any problems with lumpy cams” …………. And so have I ……… you see the thing is you never know when it is going to let you down, but when it does, the cost of the damage far out weighs buying the right valve train components in the first place………………. Ron.

 


Why use Roller Rockers?

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