Changing Rocker Arms for more HP from stock heads & cam?

**TxSwimDad** · 06-05-2007, 11:15 PM

One thing I have not noticed is where anyone has changed the rocker arms to a different dimension to gain a little hp or torque.

I'm not interested in swapping cams yet, but this might be something I'm interested in. I have heard where it was done w/ Fords & GMs but I can't say that I have heard it done on these 5.7s or 6.1s.

Have I missed that? I don't find any references that show up in the searches.

Do they exist?

Is it not a cost effective improvement on a stock cam?

I'd like to hear from you more technical types on this one.

Thx,
Les

**HemiLover** · 06-06-2007, 12:33 AM

Bump ...I'm listening too!

**hemifever** · 06-06-2007, 07:55 AM

I've not seen aftermarket rocker arms for the 5.7's or 6.1's.

**MadCharger** · 06-06-2007, 07:59 AM

Originally Posted by hemifever

I've not seen aftermarket rocker arms for the 5.7's or 6.1's.

They're out there - for about $3500 from Jesel......

**FloridaRT** · 06-06-2007, 08:12 AM

I had them on my old 96' Chevy Impala SS, and they did help.

Had rollers on all the valves, stock ratio on the exhaust, high lift on just the intakes.

Have not seen anything for our cars.

Bob

**2005rtmag** · 06-06-2007, 10:22 AM

Just check it out thoroughly before you try it. I tried to put some 1.6 ratio rockers on my old chevy 305 and the pushrods were rubbing against the intake side of the hole in the head. This hole needed elongating to make them work. This required the intake being removed to make sure no metal got into the oil. It was a bigger job than I originally thought.

**MomsR/T** · 06-06-2007, 11:13 AM

as far as I know, there is no dirrect swap.

Basicly, a longer rocker will give you more lift but doesn't effect overlap nor duration.

It works kinda like this:

Imagine you have a set of 1.6 rockers and a .500 lift cam. You now want to put on a set of 1.7 rockers to gain some lift..................how much lift would you gain?

500 / 1.6 x 1.7 = 500 / 1.6 = 312.5 x 1.7 = 531.25

So a .500 lift cam with that had 1.6 rockers replaced with 1.7 rockers now has 531.25 lift.

In MOST cases this does nothing if you have a properly designed cam for your application...................however, "back in the day" we might replace just the exhaust rockers when we stepped up to a big shot of nitrous to gain some exhaust flow from all the added nitrous.

(the proper way was to actually replace the cam to something speced for such an application.............but we were poor and made due with what we had.

)

**HemiLover** · 06-06-2007, 11:28 AM

Originally Posted by MadCharger

They're out there - for about $3500 from Jesel......

Might as well get new heads....

**TxSwimDad** · 06-06-2007, 11:35 AM

Originally Posted by MomsR/T

as far as I know, there is no dirrect swap.

(but we were poor and made due with what we had.

)

Originally Posted by HemiLover

Might as well get new heads....

When I'm out of the "poor house" I might go for those new heads & a cam. My 3 teenage daughters that have expensive sports are keeping there for a while longer. Oh then there's college...then weddings... ummm...nevermind.

**MomsR/T** · 06-06-2007, 12:16 PM

Originally Posted by TxSwimDad

When I'm out of the "poor house" I might go for those new heads & a cam. My 3 teenage daughters that have expensive sports are keeping there for a while longer. Oh then there's college...then weddings... ummm...nevermind.

I hear ya dude.............you know you're preaching to the choir.

**Rev.Hammer** · 06-06-2007, 01:16 PM

Another factor to consider is that you are limited by Valve to Piston clearance. Looking at what your gross lift would be, either you get custom pistons or....

Also higher ratio rocker arms tend to slightly increase off seat valve duration.

As of this time... I would find something else to eat up that 3500.00 that would make you happier....

**GasGunR** · 06-06-2007, 02:56 PM

Rev,

How could they increase duration? The valves would open farther in the same amount of time as before no?

Originally Posted by Rev.Hammer

Another factor to consider is that you are limited by Valve to Piston clearance. Looking at what your gross lift would be, either you get custom pistons or....

Also higher ratio rocker arms tend to slightly increase off seat valve duration.

As of this time... I would find something else to eat up that 3500.00 that would make you happier....

**Rev.Hammer** · 06-06-2007, 05:26 PM

drat... I got that backwards in my head.
The velocity changes as the time stays the same.... Jeez I gotta get more than 4 hours sleep a day...

**HemiLover** · 06-06-2007, 09:12 PM

Originally Posted by Rev.Hammer

As of this time... I would find something else to eat up that 3500.00 that would make you happier....

yeah like an AirHammer, a ShiftHammer and a trip to Hawaii!!

**CrAzYMoPaRGuY** · 06-06-2007, 10:25 PM

Duration stays the same, overlap stays the same, the LSA doesn't change, it's just more lift.
I'm not sure what the clearances are, but pushrod clearance, valve to piston clearance, and valvetrain geometry will all be affected by more gross valve lift with a higher rocker ratio.

Might give a little more top end power on a car with decent intake/exhaust?