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TW springs are rated for .540 lift
Stage one cam has 221/225 duration, 112 lsa, and .499/510 lift but should be .529/540 with Summit 1.7 roller rockers.
Some people say 1.7 add .030 and some say .032.
I just want to see if anyone is using this combo, with out any problems.
 

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I've heard that to caculate lift going from 1.6 t 1.7 is to divided lift by 1.6 then multiply answer by 1.7. For example:

0.499/1.6=0.311875 then 0.311875 * 1.7= 0.530

0.510/1.6=0.31875 then 0.31875 * 1.7 = 0.542

Either lift number for the exhaust (0.540 or 0.542) is right at the limit of the spring's rating. You might get by but run risk of exhaut valve floating at higher rpm and premature wear of exhaust valvetrain components.

I've never tried running that close to the spec. So I cannot give you any experienced answers - only theoretical.
 

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thats exactly what im running. its been working very well for me. ive had it this way for about 10k miles. eventually when i tear it all down again to do some porting on the lower intake, i plan on upgading springs. who knows maybe at this time i might have a little port job done to the heads as well.

if money is tight go ahead and use the stock springs, and then later on, plan on upgrading the valvetrain.
 
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