School me on rockers
08-22-2010, 10:04 PM
#21
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Scorpions.
Both my son and I have 96 LT1s and both are running Scorpion RRs, 7/16" stud, full, Non Self-Aligning roller rockers. His are 1.7/1.65 ratio and mine are 1.7/1.7 ratio.
They are very high quality and unlike Pro Mags or Crane Golds, are quiet runnng. $222 a set.
BTW, steel rockers are most desirable in high RPM applications when very high spring pressures are being used; the reason is to minimize deflection. Don't get caught up in a steel Vs aluminum debate. For a streetable engine, aluminum rocker arms have absolutely no draw-back or down side Vs steel.
Jake
Last edited by JAKEJR; 08-22-2010 at 10:15 PM.
08-22-2010, 10:39 PM
#23
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http://www.summitracing.com/parts/CCA-1605-16/
Here are the ones I have, you'll need guideplates, hardened pushrods and 7/16ths inch screw in studs to make it all work.
Here are the ones I have, you'll need guideplates, hardened pushrods and 7/16ths inch screw in studs to make it all work.
08-22-2010, 11:23 PM
#26
Can the stock ones last?
Is it worth the expense of an aftermarket full roller?
What are the benefits/disadvantages of a full roller over a solid rocker?
Edit: For what it's worth, I'll be going with at minimum a 226/230 .565/.565 cam, I'll likely go bigger though.
Is it worth the expense of an aftermarket full roller?
What are the benefits/disadvantages of a full roller over a solid rocker?
Edit: For what it's worth, I'll be going with at minimum a 226/230 .565/.565 cam, I'll likely go bigger though.
If you are going to with a large lift you may be forced to use a full roller if the rocker arm stud slot is not large enough.
Below are some comparisons of the two.
The stock LT1 rockers have the standard stamped rocker that is self aligning. Self aligning means that the rocker tip has means of preventing it from slipping off the side of the valve stem.
Now in this picture you see the rocker ball on a stock 95 Corvette LT1 engine, there is substantial wear on this, almost all after market stamped rockers will use these but they will have little grooves cut into them to help oil cool them
This is a stock stamped piece, as you can see it is made from one piece of steel, you can see where the rocker ball sits and causes wear in the rocker arm. Also notice on the rocker tip there is two indention marks, the valve stem sits between these marks. In the rear of the rocker you can see the oiling hole which is not small and not centered as they are trying to aim the oil forward for the springs and rocker ball.
Also notice how small the slot is for the rocker arm to pivot in, with large lift you can end up with the rocker bottoming out against the rocker stud and the weakest link will break, that would be the rocker arm, the stud, the pushrod, or the lifter.
These are 1.6 Comp Cams Steel Pro Magnum rocker arms, they aren't made like this anymore, they have the ultras and some other ones. On this you'll see the roller tip and the roller pivot. Steel rockers are heavier than aluminum rocker arms, but the because of the greater strength of the steel the mass over the valve is not much more than aluminum rocker arms that have to be much beefier over the valve.
On the top right of the first picture is the nut that is used on top of rocker ball to adjust your valve lash and to hold the rocker arm down. This nut has little flat spots so that the threads aren't perfectly round so that there is a lot of friction as you screw it on the the threads of the rocker stud. This added friction helps keep it from rotating and loosening, it seems like it doesn't work, but on stock engines it does fine. The other type is the poly lock, which you turn the outside nut to adjust the lash and then lock it in place with the allen set screw in the middle of the poly lock.
Finally with large lifts the rocker arm tip is making a arc as it travels so the tip moves across the valve stem. With higher lift numbers the tip on a stock stamped rocker arm will move quite a bit on the tip of the valve stem which as stated by someone before causes side loading on the valve stem. With a roller tip the side loading is reduced.
Also before you pick a camshaft deciding what kind of HP/TQ and where you want to make it should be considered. I have a camshaft that has the same lift as your minimum camshaft and makes a bit over 400HP to the rear wheels.
Sorry for the long post.
08-23-2010, 01:24 AM
#28
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I had talked to Lloyd Elliott about a cam, and he suggested going 236/240 (IIRC) with my set up which has a Vig 4000 and 4.10's.
Would I have to respec the cam if I wanted to go with a higher ratio rocker? Or would it even be worth the minimal gain at that size of a cam? I also plan on getting LE2 heads down the road, FWIW.
Would I have to respec the cam if I wanted to go with a higher ratio rocker? Or would it even be worth the minimal gain at that size of a cam? I also plan on getting LE2 heads down the road, FWIW.
08-23-2010, 01:38 AM
#29
He was using a rhoads lifter, which at idle pumps down and creates more valve lash. Some of those pictures you can see where the rocker arm nose slipped off the valve stem and started chewing up the aluminum body. I bet there is some rubbing in the pushrod holes and on the pushrods themselves. This guy should have used guideplates. Also he is using variable lift rockers and variable lift lifters, not too smart.
08-23-2010, 01:52 AM
#30
I had talked to Lloyd Elliott about a cam, and he suggested going 236/240 (IIRC) with my set up which has a Vig 4000 and 4.10's.
Would I have to respec the cam if I wanted to go with a higher ratio rocker? Or would it even be worth the minimal gain at that size of a cam? I also plan on getting LE2 heads down the road, FWIW.
Would I have to respec the cam if I wanted to go with a higher ratio rocker? Or would it even be worth the minimal gain at that size of a cam? I also plan on getting LE2 heads down the road, FWIW.
08-23-2010, 02:28 AM
#31
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Upper .500's, possibly into the .600 area, it really depends what I finally decide on. This cam is just a part of future mods, so I won't have to spend extra on another cam.
08-23-2010, 10:23 AM
#32
The main advantage of the roller rocker is the loss of friction that the ball and socket cause. This is also one of the weak points. The other advantage of the roller rocker is the tip, it is easier on the valvetip than the stamped style rockers. The stamped style rockes also sometimes interfere with larger diameter valvesprings.
The places I have seen the stamped style rockers fail are the pushrod cup and the bowl and socket area.
With that cam and the pring pressures required I would go with the full rollers for peace of mind.
The places I have seen the stamped style rockers fail are the pushrod cup and the bowl and socket area.
With that cam and the pring pressures required I would go with the full rollers for peace of mind.
08-23-2010, 11:08 AM
#34
The next best option is 7/16" studs. You would be surprised at how much the stock stuff moves around.
To the OP. In regards to buying rockers, cheaper is very rarely better. Buy the best quality that you can afford.
08-23-2010, 11:25 AM
#35
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There have been failures with many companies that make rockers. Comp Cam rockers have failed numerous times for people. I wouldn't single out Scorpion.. FWIW I run them and have had them on for years. Prior to that I ran the Crane gold's (which were also great) but I needed to switch to an NSA rocker and am glad I went with these. They are a very nice piece. Local to me also 
08-23-2010, 12:05 PM
#36
Just for the record, I never said that he needed shaft rockers. I stand by the statement that they are the best option.
The next best option is 7/16" studs. You would be surprised at how much the stock stuff moves around.
To the OP. In regards to buying rockers, cheaper is very rarely better. Buy the best quality that you can afford.
The next best option is 7/16" studs. You would be surprised at how much the stock stuff moves around.
To the OP. In regards to buying rockers, cheaper is very rarely better. Buy the best quality that you can afford.
