Author Topic: roller rockers  (Read 2756 times)

pjbizjak

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roller rockers
« on: May 06, 2021, 11:17:12 PM »
Hello, I have a 68 z/28 camaro with the 302 290HP engine and I'm wondering if roller rockers are worth it? Right now I have roller 'tip' rockers. The engine has had some mild work done but all to resemble factory specs, bored 40 over, Comp Cam cam components, lifters, pushrods and solid 30/30 equivalent cam and valves and valve springs.

bcmiller

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Re: roller rockers
« Reply #1 on: May 06, 2021, 11:24:38 PM »
Probably won’t make much difference.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

crossboss

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Re: roller rockers
« Reply #2 on: May 07, 2021, 01:46:30 AM »
Probably won’t make much difference.



+2. Don't believe those Hot-Rod and Car Craft articles claiming you will gain 25-50 HP.
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MO

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Re: roller rockers
« Reply #3 on: May 07, 2021, 04:16:02 AM »
I don't know what the hp gain would be, if any, but there would be less friction and wear with roller rockers.

169INDY

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Re: roller rockers
« Reply #4 on: May 07, 2021, 04:34:01 AM »
I was with Friends at Tacoma Wa, Cope Brothers Machine Dyno Cell yesterday 5/5/2021 & "Whimpy" 1969 CE 302 Spun to 6,700rpm @ 381hp Shook the ground,  What a SOUND!

Equipped: Harland Sharp Original Roller Rockers, Rocker Arm, Stud Mount, Full Roller, Aluminum, 1.5 Ratio, Fits 7/16 in. Stud, Chevy, Small Block, Each

Do most guys Run: COMP Cams Magnum Steel Roller Tip Rocker Arms as a min ??
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS
68 Z28 M21 LOS

buenymayor

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Re: roller rockers
« Reply #5 on: May 07, 2021, 09:11:07 AM »
Probably won’t make much difference.

x3. Spend the money where it will do some actual good. Roller rockers have their place, but they are over-sold.

usa1ti

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Re: roller rockers
« Reply #6 on: May 07, 2021, 12:19:49 PM »
Probably won’t make much difference.

X4. There are really only 2 reasons to use roller rockers. (1) when the camshaft lift at the valve tip exceeds the stroke of the slot length in the rocker arm. You then start to break things. (2) You want to change the ratio to give the valve more lift without changing the camshaft. They provide little or no performance increase. Only reliability improvements with camshafts generally over .580" lifts at higher RPMs. 
Todd, East TN

Stingr69

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Re: roller rockers
« Reply #7 on: May 07, 2021, 01:36:10 PM »
Depends a lot on the cam.  The factory valve train design was dictated by existing parts.  Slow ramp rates allowed stock valve train pieces to work.  If you increase the ramp rates on the aftermarket cam lobes you need stronger springs to control the valve train. Stiffer springs and steep ramp rates combined with higher RPMs increases the load on the valve train.  Too much load on the rocker arms causes breakage and can burn the rocker arm ball pivots. 

Once you exceed 350# of valve spring pressure over the nose at full lift, the rockers generally need to be upgraded to needle bearing full roller rockers.

Truth is, the original pivot ball design is pretty slippery as it is, so friction reduction alone does not release measurable difference in power.  The roller rockers are really needed to handle the higher valve train loads. 

You can buy them and put them on easily, but they do not increase power by themselves. Do it only if you really need them is my suggestion.

KurtS

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Re: roller rockers
« Reply #8 on: May 08, 2021, 04:32:20 AM »
If you get a cam that can put the potential to use, possibly... Bit of a rabbit hole.
Kurt S
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68L30

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Re: roller rockers
« Reply #9 on: May 08, 2021, 02:44:28 PM »
I had a set of Harland Sharp, took them off my 68 and replaced them with the Competition roller tips. They needed to fit under my orig valve covers. No difference on a .510 flat cam. Been on almost 30 years. I do have guide plates, screw in studs, big springs w/ Race Flo valves. This was my concession to appear stock.

Steve

firstgenaddict

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Re: roller rockers
« Reply #10 on: May 09, 2021, 05:27:35 AM »
IF you have non dripper covers you can fit aluminum needle bearing with the felpro double cork with steel sandwich and the original bolts will bearly pull down.- we had a .636 solid roller. under non dripper covers. 
Aluminum are a little less inertia in the rocker assembly, high revs it makes a difference, however for longevitity you would want to run a SS needle bearing - ideally shaft mounted, most people are not going to go through the trouble of figuring the correct length pushrod for their application and should stick to a set of long slot 1.50's which are nominally 1.37 

IF you have a Z28, and stock rocker arms - If it were mine I would have, I adjust every stock solid lifter cam as per the flat tappet clearances as laid out by John and Duke, in their paper which takes into account the 1.37 ratio and thus removes a lot of the slack in the valve train, it is much easier on flat tappet solid lifter cams because it allows the valve to come to rest at the cam ramp velocity.
IMHO - Tigher clearances can only equal increased valve lift.
This only Applies to Solid Lifter cams - Z28's, Fuelie Corvette, LT1, all different clearance specs.
« Last Edit: May 09, 2021, 05:49:19 AM by firstgenaddict »
James
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crossboss

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Re: roller rockers
« Reply #11 on: May 09, 2021, 04:03:17 PM »
Aftermarket roller rockers are not needed for a stock or even a mild performance application. They are more of a hassle, and cost then the gains (IF any) you will achieve. That said, on any serious build, racing, endurance (Trans-Am), or a drag race engine, yes by all means you NEED them. Stainless is best for endurance, and alum for drag racing. Also, make sure your valve train geometry is correct no matter what application/brand/or engine you choose to use them on. High lift cams, heavy spring pressures, stiff pushrods and guide plates/shafts require a quality made rocker arm. Lastly, always follow the cam manufacturers required valve lash for hot and cold settings.
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Kelley W King

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Re: roller rockers
« Reply #12 on: May 10, 2021, 11:57:57 AM »
If you are going racing fine. If not just more moving parts to fail. I wonder if JM runs them on his 67  302 race car?
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

janobyte

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Re: roller rockers
« Reply #13 on: May 10, 2021, 03:14:07 PM »
Thought he was running comp high energy long slots.could be wrong. Hear Howards makes a good stamped rocker. May be subject to class rules.
 Left the HS's in mine purely for sentimental reasons...plus the stock covers cleared with a double gasket.

Race engine we run HS's with a girdle,,but engine wise, apples to oranges. Good for the application.
For a very serious application, I'd go shaft mount. BB's, my buddies say a must.
68 Z/28  born with: 302, drive line, etc..

crossboss

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Re: roller rockers
« Reply #14 on: May 10, 2021, 06:13:42 PM »
If you are going racing fine. If not just more moving parts to fail. I wonder if JM runs them on his 67  302 race car?



Im quite confidant 99% of all the Trans-Am/Vintage guys are. I did. Btw, 'most' racers today are not 100% as they were 'Back in the day' on the parts...at least what you can't see. That is however another topic...
Just another T/A fanatic. A new project in the works.

 

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