Hi all, I have a 1981 Chevy K1500 4x4 with a ZZ4 350, 700r4 tranny and 4.11 gears with an Eaton locker. Right now Im pushing 390 hp and 415 torque. I am looking for more power and I want to start with roller rocker arms. I belive there is a H.O.T. cam in the engine at the moment. I was searching around at Jegs and found a decent looking set of rockers from Crane cams. They are aluminum rollers with 1.6:1 ratio. Would this be a decent set? Also, would I need to replace the valve springs or not? Also should I make any other modifications at the time of a rocker arm change? Thanks alot for any help you can offer-James  

well roller rockers arent exactly the best bang for the buck buy on the market but they are worth something, and are required for heavy valve action over .500 lift for decent guide wear but a ratio increase really only shows the best value if the engine is under-cammed for the displacement/cylinder head volume, also ratio increases on the exhaust are usually worth next to nothing except for a couple numbers at the top for a naturally asppirated engine that has something sufficient for ridding of the exhaust, ratio increases slightly reduce low end power and may slightly reduce mileage but on CHP's Impersonator 406 with Vortec Heads and 230@.050 duration cam a 1.6 over a 1.5 rocker made some 24 HP more at the top end

valve springs shouldnt need to be changed if they dont have a lot of miles on them, ratio increases usually dont effect valve control to drastically, some things that come to mind are piston to valve clearance and guide boss to retainer clearance, and coil bind checking is all i can think of

I plan on installing a nitrous system after the install of the rockers. Would it then be preferrable to have the roller rockers or to just stick with the stock?   thanks  alot -James  

i guess one could argue that keeping stock stamped rockers would accelerate wear when the nitrous was on but not unless you were squirting the engine for passes i wouldnt worry

i dont know, the ratio increase of the aftermarket rocker might give quite the advantage on the top end on the exhaust side with the nitrous, giving the cylinder more exhaust valve area to blow down faster when there is extra exhaust volume to handle when the juice is turned on, especially if the exhaust ports are un-ported and doesnt have all the velocity it could, and or if the cam is single pattern/street profile, or thats at least what i would think on paper

i didnt know the ZZ4 350 had forged pistons?

At Pace Performance the description of the pistons is:

Pistons- Part # 10159436 Hypereutectic<COMMA> flat top <COMMA>With offset pins. Same piston that is used in Corvette LT1 engines.</COMMA></COMMA>

I am unsure of what all of that means. -James<CRLLINEFEED>

</CRLLINEFEED></CRLLINEFEED>  

1.6-1s will likely buy you something. maybe not much now but if your cam is still a little small they will net some hp.

1.5-1 rollers are a better buy as they will offer the friction reduction of the roller and transfer well when you get ready for a bigger cam. I own a set of 1.6-1 summitracing rollers and they are just as good as the cranes for less money ( i own a set of cranes as well ).

There are lots of naysayers on this board for roller anything, I am convinced they are worth the price of admission. YMMV. I think flat tappets and friction rockers are a crude means to an end. Not that they didn't suffice for a long time though.

one mans opinion

"There are lots of naysayers on this board for roller anything"

I'm probably one of the naysayers you refer to.  IMO, it's more like understanding the facts rather than falling prey to good marketing tactics.  Rollers are great... if they're properly applied.  90% of the time they're not - and the consumer just wasted a bucket of money that could have been spent on something more useful for his street ride.

One needs to understand their benefits:

1.  Roller rockers are most beneficial for reduced heat via less friction, not power increases.  They're at home in extremely high rpm engines and/or endurance engines.  On a street engine, you're not going to gain one iota of increased power by swapping out the stamped rockers.

2.  Roller cams enable the cam to:

A)  Be ground with extremely aggresive lobe ramps which open/close the valve much quicker than a flat tappet cam.  Air flow is not significant until the valve is off the seat by 0.050" (one reason this measurement has become the standard).   

B)  Utilize extremely high spring pressure.  

Nearly all power gains from a roller vs. flat tappet cam is due to different valve timing and lift, not reduced friction.  For a street mill, there's plenty of flat tappet cams which will provide equal power. 

Net net, roller rockers/cams can be very beneficial in high rpm mills.  Sure you can buy them for a street engine and be perfectly happy - but you're not going to gain anything other than a reduced checkbook balance. 

Caveat Emptor.

I own a set of 1.6-1 summitracing rollers and they are just as good as the cranes for less money ( i own a set of cranes as well ).

I agree that i would think most aftermarket aluminum rockers would be created equal but im not a big fan of aluminum rockers especially something with some high strain that will also see some miles put on em and quarter mile passes, then id go stainless without a doubt

There are lots of naysayers on this board for roller anything, I am convinced they are worth the price of admission. YMMV. I think flat tappets and friction rockers are a crude means to an end. Not that they didn't suffice for a long time though.

I think im also one of the naysayers you'are referring too, i am convinced that i am much more budget orientated than you and dont have that much money to throw around yet still in mild street combinations can net the same power as rollers with flat tappets, i found oldbogie's disscussion about rollers versus flat tappets interesting that people think since the lobe on the roller is peaked that it accelerates the valve ungodly fast and holds it at max lift it's entire duration but thats just un-true, i also found a comment (but i cant remember who made it) on our last roller versus flat tappet comparo very interesting, it was said that flat tappets dont create very much friction otherwise they wouldnt live for thousands upon thousands of miles in street driven cars everyday