Do aftermarket rocker arms alone increase performance?

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Jan 30, 2004 | 07:58 AM

#21

lowdowndirty

Burning Brakes

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From: "In a van down by the river" CO

Re: Do aftermarket rocker arms alone increase performance? (XTrooper)

Ok, Ok. I didn't have any concrete figures, I just know it's true. (Like we've both said.) Now, if the 1-2 degrees is in advertised duration, this would qualify as "barely". But if the 1-2 degrees is at .050" lift, then it is somewhat considerable. Anyway, we're on the same page, just of a different language I guess and thanks for clearing that up! :D

Jan 30, 2004 | 08:09 AM

#22

XTrooper

Drifting

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From: NE PA

Re: Do aftermarket rocker arms alone increase performance? (lowdowndirty)

I'd forgotten myself, Chris, so I looked it up. It's an increase of 1-2 degrees of duration measured at the valve at .050" lift. :thumbs:

Jan 30, 2004 | 06:43 PM

#23

cliffkh

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From: kansas city KS

Re: Do aftermarket rocker arms alone increase performance? (lowdowndirty)

Quote:

:withstupid: This is not true. If it were, then why even go with a bigger cam. Upgrading with even a moderately bigger cam will give you more power(generally speaking). Increasing rocker arm ratio effectively increases valve lift, same as going with a bigger cam. It is true that he won't see huge gains, but there is some to be had. And there are plenty of cam only cars (meaning stock heads) that have gobs more power than stock.

Absolutely. They also aren't getting that power from lift only. I'm sure some increase could be had with lift only on a stock duration cam but it would not be very much - about like adding 1.8 rockers.

Which means the combination of duration and lift increases they are getting from the new cam are producing more power. And...I didn't mean to imply that the stock heads aren't good for any more power through lift - just that the extra lift has to be producing increased flow by whatever heads you have to be doing you any good. Some heads flow better than others - if your heads don't flow more at the higher lift I don't think you will gain anything (unless you add duration). Oh and you have to be able to get the extra exhaust outta the way as well ...

At least that is my simpleton view on it. :)

Jan 30, 2004 | 10:46 PM

#24

Jochen

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From: Munich Bavaria

Re: Do aftermarket rocker arms alone increase performance? (cliffkh)

Interesting discusion. So i might see some gains from installing 1.8 (or 1.85) rockers (or roller rockers) with my bolt on C5. Thats one point. Will there be any evidence for an outside inspection (emmision inspection as well) to realize the changed rockers ? I am thinking about worse emmisions or an unusual drivetrain noise which might let the inspector think something was changed at the car . . .
Valve cover clearance was mentioned. Companies advertise the valve cover clearance with their rockers. Any Problems with that ? And how does the covers have to be machined (or exchanged) if the clearance is not enough ?

Another point is the pushrods, which might be very easy to exchange ones the rockers are off. Will there be an increase in perfomance by installing lighter (Z06) or other aftermarket pushrods ? Any recommendations on what brand to buy ? AND, when changing those parts (considering staying with the original springs) how much higher might i set the Rev limiter without damaging the engine (or those parts) ?

Thanks,

Jochen

[Modified by Jochen, 4:49 AM 1/31/2004]

Jan 31, 2004 | 02:24 AM

#25

lowdowndirty

Burning Brakes

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From: "In a van down by the river" CO

Re: Do aftermarket rocker arms alone increase performance? (Jochen)

Ok, there is no way to tell you have aftermarket rocker arms (either roller or full roller) w/o taking off the valve covers. There should be no discernable noise difference between a quality set of rockers and the stockers (as the stockers are rollers anyway). If the manufacturer states their rockers have no clearance issues respective to their application, then it's probably true. (If the advertisement is for LS1 rockers, then there should be no issues as they are engine-specific., keeping in mind that they're citing this with a stock cam). Lighter pushrods will not provide you with more power. If they are hardened, then they will provide less flex (less stress on rockers and more accurate valve operation) and lighter valvetrain weight, which allows more RPM. But with a stock cam, you're probably out of power around 6000.

Jan 31, 2004 | 11:16 AM

#26

Dr.Ron

Le Mans Master

Joined: Jun 2003

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From: 2007 Nat'l Corvette Challenge 11.50 index Champ. New Jersey

Re: Do aftermarket rocker arms alone increase performance? (billmartin)

Bolting on the rockers is not too difficult. I remember when my friend did my roller rockers (higher ratio than stock) on my Mustang he had some difficulty shimming them correctly. Not sure on the Vette if that's an issue. They did give me some SOTP feel though....Upgraded stock rockers are probably a waste of $$$. :flag

Jan 31, 2004 | 02:34 PM

#27

Jochen

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From: Munich Bavaria

Re: Do aftermarket rocker arms alone increase performance? (lowdowndirty)

Great info, thanks. i guess i will go with the 1.8 or 1.85 ratio setup. Just looking around what brand (slp . . .)

Thanks again.

Jochen

Feb 1, 2004 | 09:20 AM

#28

XTrooper

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From: NE PA

Re: Do aftermarket rocker arms alone increase performance? (Jochen)

Quote:

Great info, thanks. i guess i will go with the 1.8 or 1.85 ratio setup. Just looking around what brand (slp . . .)

Thanks again.

Jochen

I got the SLP 1.85 versions, but only because the Comp Cams 1.85 roller tip versions weren't available at the time. If I were doing this mod today, I'd get the Comp Cams 1.85s.