Will changing over from stock rockers to a roller rocker increase HP, or is this just a way to increase the cool factor and decrease friction?

Thanks

 

The only thing is will do is reduce the amount of friction between the two metal parts. It does add a little coolness factor but I did it for longevity sake. I have a set of scorpian rockers and haven't had any issues yet. If I had to do it again I would run a set of roller tip rockers verse the full roller.

 

less friction = more hp

 

What engine do you have?
Just changing to roller rockers will not increase horsepower.

 

I have a 351 cleveland

 

Changing to roller rockers has several advantages.

The stamped rockers add a lot of friction and build heat in the oil. The stamped rockers are also off a good deal on geometry and ratio. If you plot the actual lift ratio of a rocker from zero to full lift you will see the ratio jump all over the place. I have seen 1.5 "off brand" rockers that varied from 0.9 to 1.45 through their travel, never actually reaching the advertised 1.5 ratio. This comes from loose production tolerances and the location of the fulcrum moving it's rotational axis as the rocker moves through it's arc.

A roller lifter has tighter tollerances, the fixed rocker trunion keeps the ratio truer and they build less heat. You might see a 1.35 to 1.55 in the same rocker through it's travel in the example listed above.

You DO pick up HP with roller rockers, it isn't a huge amount in most motors. It really depends on how far off things are on the stock piece to begin with and how good the rocker is you put on. Scorpion are at the higher end of the less expensive rockers. Go to a T&D or Jessel shaft system and you will pick up even more. They also cost around $1000 a set! The benifits of cooler oil will extend valve spring life and that's a bonus.

If I were switching to roller rockers, I would also make the switch to 7/16 studs at the same time or go to a stud girdle. You will lose as much HP to stud deflection as you will to stock rockers. Stopping that deflection will pick up even more HP. This is all if you actually turn more RPM than just driving around town. Anything under 4500-5000 and a mild to stock cam and it's more bling than go!

JMO,
SPark

 

Thanks for the explanation. I plan to take apart the 351 and whats what. Previous owner supposedly rebuilt it but I will have to measure some things to be sure. The engine sounds good, but doesn't have much of a lope. I will probably change out the cam to be a little more aggressive. The price for parts on this engine are a heck of a lot better than when I was looking into rebuilding a 390. Big engine big price I guess. The truck currently has a 2.75 rear end that is way to low and will be changed out also. Kinda runs like a turd with that rear end.

later

 

I need to correct that statement. I should have said roller rocker, not roller lifter.

You won't hurt anything putting the roller rockers on the motor. If you are going through it, I would go ahead and do it. They're a hundred bucks or so more than stockers but I always do it out of habit. I just feel better with them in there than the stamped steel pieces. You might also want to consider going to chrome moly roller rockers. They actually are lighter where the valve sees the weight and have a longer duty cycle than aluminum rockers do.

You may have to convert to screw in studs with guide plates when you do this, depending on what heads you have. Also watch the cams out there for Cleveland motors. Some of the solid cams that are more radical can be 1.6 ratio. We have them ground for 1.6 and 1.73:1 ratio rockers and have had them both ways depending on the motor. Be sure the cam and rockers are the same ratio. Shouldn't be a problem with the milder stuff or hydraulic cams.

Want a really nice motor for it? Got a Yates headed/Roush short block 12.75:1 motor for sale! Motorsports block, Bryant crank, Carrillo rods, Weisco pistons, roller cam, Jessel shaft rockers, spring oilers, aluminum dry sump pan. Would make a killer truck motor. That'll move it down the road!

SPark

 

Not on pump gas...

 

We only pay $6.50/gal for 112 octane and it comes out of a pump!

SPark

 

Wow, only $125 per tankful!
At the rate things are going 87 octane will soon be $6.50 a gallon.

 

If this guy is right, we're all being taken for a ride...

Listen to this and draw your own conclusions.

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