rocker arms

[mdiacont322]

I read on summit racing that if you increase the rocker arm length, you can gain some performance out of your existing cam. I was wondering if anyone has switched their rocker arms and had a noticeable difference. Any input would be appreciated.

Mike

http://www.summitracing.com/expertadvice/professoroverdrive/default.aspx?techQuestion=111

 

[SunlitComet]

that doesn't sound right. are you sure it is not pushrods which is still risky I think.

 

[DBLTAP]

I like Summitt and have spent a ton of money with them over the years, just remember that they are looking to sell you something. I personally i wouldn't start at the top and work down. Bang for your buck here is replace the painfully anemic cam with one that matches your intended purpose for the truck. Rockers-There is more than one piece to that puzzle. Might do some additional valve train study from a few neutral sources.
If you're running vortec heads here's one to get you started, be sure to follow the link at the top of the page to the Performance Chevy article: http://www.2quicknovas.com/vortecheads.html

 

[blueflamed03]

going form a 1.5 rocker ratio to a 1.6, will give it more lift, that is all....I'd replace cam if you want more duration/lift. On a stock motor, you wont see a benefit.

 

[retorq]

It will give slightly more lift and slightly more duration but 1.6s are generally not a bolt on deal, you have to check rocker arm geometry and pushrod length. Now if you were going from a stamped steel rocker arm to a full roller setup in the same ratio, that may be worth the hassle ...

 

[arb905]

Mike just go with it, if you don't want the hassle of pulling the cam. Yes it could help with performance check the specs of the current cam and swee what the new rockers would make the cam. The rocker arm is just the fulcrum for the cam. What Summit said is true. Adverstised cam specs are set for a specific rocker arm ratio. Just make sure the valves don't make contact with the head and the valve springs won't bind up before full lift. (All things you'd have to do with a new cam).

 

[Phone Man]

I went through this myself. If you get 1.6 ratio rockers, the vortec heads need to be machined for push rod clearance because they will hit slightly. I went with replacing the stapmed steel with the stock 1.5 ratio rollers.

 

[blueflamed03]

yep, valve guide bosses need trimmed if going to a higher lift, if Vortec.

 

[mdiacont322]

I figured since i am getting a long block for the truck i would bring this thread back to the top. To figure out the lift with different length rockers, divide total lift (intake- .414; exhaust- .428) by your rocker arm size (1.5). Then take that number and multiply it by your new rocker arm size.

The new lifts would be-

intake- goes from .414 to .442

exhaust- goes from .428 to .457

I plan on going through with this, so, my main three questions are...

1) has anyone (cam swap or not) had any problems with a 1.6 rocker and stock length pushrods?

and

2) will i need to buy 'tall' valve covers?

and

3) will I benefit from roller rockers?

Mike