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1.65 ratio rocker woes

ari666

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hey. just noticed on the crane 286 cam card that the lift is calculated on 1.6 ratio rockers, mine are 1.65.

what effect would that have on lift? and how do i work out the extra x 0.05

advertised lift= .496 calc on 1.6 so divide .496 by 1.6 then times by 1.65? would that work? it brings me up to 511.5. and i am not sure if my valve springs can handle that...

worried

thanks
 

Boonz

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depends what the spring seat pressure is.... do you know if you left the buckets ontop of the springs or took them out?
im running the street terra 1.65 adjustables... isky blue springs at 130 Lb seat pressure with a 286 cam.... havent had a problem but my springs are different to yours....
how come you didnt go a little bit higher lift spring to allow for a bit more tolerance?
 

ari666

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how come you didnt go a little bit higher lift spring to allow for a bit more tolerance?
no, i did. they were suited to 495 lift cam, but cant remember the lbs pressure. had a mini freak out when i worked out 511 lift, but my friend assures me that the springs we fitted dont bind till 550 so its all good.

but does that calculation sound right?
 

crazybiker

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Yup. .511" lift is right.
 

Boonz

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you will only get valve bounce at stupid high revs then with the springs that are in there.... should be right for your combo
 

greenfoam

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ari666, it's not only the lift you have to worry about it's the rate it increases or how aggressive the lobes are. But anyway I'm sure the 286 use to be 286 degrees duration advertised and that would have made it really agressive but now they are listing it at 292 degrees and having more mild ramps so go figure that :) it's got me beat how come a 286 is a 292. Either way whatever it is it usually craps out above 5500 rpm on LT1 springs and needs better springs than that
 
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