WS6FirebirdTA00

iTrader: (33)

i ordered a set of heads from rapid and i was reading this on the afr site

Note:
Hydraulic roller cams in "LS" Gen III engines typcially experience valve float at 6600-6800 RPM's. If you plan on running over .600 gross valve lift and/or 6600 RPM, AFR suggests you upgrade your springs to AFR part #8014. Our upgrade spring has higher seat and open pressures (145/380+) to better reduce the risk of valve float in more aggressive applications. AFR also recommends the use of Comp "R" lifters in conjunction with our 8019 spring upgrade.

i thought these heads came with dual springs rated up to 650 lift? or am i wrong?

Tony Mamo @ AFR

iTrader: (13)

AFR feels that our standard springs don't have enough spring rate for reliable valve control (at peak RPM's) with over .600 valve lift and the aggresive cam profiles that have become the "norm" today....That is the reason we rate them more conservative than most (our website should have .600 lift max. on our standard equipment 8017 LS1 spring). They can tolerate more lift from the standpoint of coilbind, but once again, for more aggressive cams and higher RPM's we advise a spring upgrade with more seat and open pressure.

We know other manufacturer's/suppliers rate that spring higher, but we felt for the utmost in reliability (and power output due to better valve control), a ceiling of 6800 RPM's and .600 lift would better serve our customers.

Thanks,
Tony

WS6FirebirdTA00

iTrader: (33)

so what would the upgrade get me? i pmed mikey at rapid about this. i will be putting in an f13 cam, .585/.595 lift and 6600-6800 redline. i wanna do it right and not screw something this big up

Tony Mamo @ AFR

iTrader: (13)

With stock rockers, we recommend the Comp 921 spring upgrade....expensive but their reputation speak for themselves....AFR PN 8004

For ANY aftermarket roller rockers and the typical increase in weight that goes along with them, we recommend our upgrade PN 8019. It is the newer style REV 1116 spring and we have dyno tests to back up the fact it handles the heavier aftermarket valvetrain much better from the standpoint of valvefloat. I know the REV springs have had mixed results in the past, but I am currently running them on my car and have been doing so for 6 months without a hitch...perfect valve control at RPM and MANY 7000 RPM blasts, both on the dyno as well as the street. I think REV had some problems with their earlier design.

We might be offering another spring upgrade in the future similar to our standard spring but with more seat pressure and additional spring rate as well. If testing goes well and we release that product to market, you guys will be one of the first to know....

Regards,
Tony M.

WS6FirebirdTA00

iTrader: (33)

so with the f13 cam and stock rockers, how do you think your springs will hold up? the ones that come standard?

Slowhawk

iTrader: (12)

FYI, we have run 234/238 with .610/,610 XER Cams with there basic spring package and have no valve float up to 7000rpm,even after having some good mileage on them.So you should be all set.Tony is just covering himself which is good.I personally won't run comp R lifter's unless it is absolutely neccessary