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Old 07-22-2012, 10:47 AM
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roller rocker ratio

Hi Guys
Finally got around to removing my camel humps,replacing them with some aluminium heads 64cc 210 runners,my cam is a 280 magnum 480 480 lift,would I benefit from replacing 1:5 rockers with some 1:6 rockers(resulting in a 510 510 lift)I was told the 210cc runners are too big for my setup?
+60 sbc,rpm intake,flat tops,600 holley.
Any imput would be great?


Last edited by dave350v8; 07-22-2012 at 10:53 AM.
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Old 07-22-2012, 11:37 AM
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Totally up to you but unless you're racing around your streets at 6,000 rpm you'll never notice the difference.
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Old 07-22-2012, 01:01 PM
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The difference will be small. You'll see more WOT power gain by upgradeing the
600cfm carb to a 750 cfm carb.
The 210cc heads are not too big. But now the carb is marginally a bit too small for max performance.

Generally higher ratio rockera re much more effective on the intake side than the exhaust side on a SBC. and generally especially if the intake cam lobe is smaller than the exhaust. the 1.6 in and 1.5 ex evens out the valve lift.

EG: say you had a cam with 219 deg in and 230 ex @.050"
.462" in .480" ex

The 1.6 intake rocker would give you .492" intake valve lift and more intake valve open area and lift with the same intake seat duration. (faster valve action+ more valve lift, within the same {short} valve open duration)
This tends to improve power especialy on ported or aftermarket heads that like higher valve lift to flow more.

The exhaust side (on a SBC) responds much more to valve duration and LSA changes to move the exhaust open close events around.
Thus the 1.6 in 1.5 rocker combo.

Your cam is still undersized so you would see a much more gain from simply changing the camshaft rather than rocker ratio.
Especially with the new high flow heads.

you can try your rocker wap but the only way to actually see if it makes a real difference is to track test it
A -B with the 1.5 rockers. The higher the rocker ratio the more critical the valvetrain control @high rpm (valvesprings)

Last edited by F-BIRD'88; 07-22-2012 at 01:08 PM.
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Old 07-22-2012, 03:16 PM
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Thanks for your replies,think I will run it down the strip see how it performs,hopefully runs quicker than the camel humps! May look at swapping the cam then,just bought some howards retro roller lifters for a future build! so i might use them with a good roller cam. always felt that the camels were holding back on the top end,or the 600 hollley. Thanks F-BIRD for your detailed advice!
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