| Re: Comp cams springs.. wtf! Vs AFR out of the box.. |
Subject: Re: Comp cams springs.. wtf! Vs AFR out of the box.. by rklessdriver on 2009/11/13 18:11:10 The Hydra Rev absolutley does NOT affect the plunger. The spring acts on the outer edge of the lifter body. .060 is accetable on the coil bind clearance... but you are almost using up all of the spring. What really bothers me about the Comp 986 spring is the lack of open pressure. Not even 300lbs... Granted you have a rev kit but still its a pretty weak spring for anything other than tooling around IMO. The base AFR 8017 looks to me to be a better match. It gives you an additional .050 till coilbind and has more open pressure at your lift. It gives you room to grow on the cam or rocker ratio in the future if you want to. IMO 340lbs is about right for a fairly aggressive HR to the low 6000RPM range. It's mfgr'd by Amercian Wire (so is the 8019) and is a good quality spring as far as mass produced stuff goes. I think the 8019 is too much spring for what your trying to do but not because of the pressure. The open pressure is not that big of a deal. Don't be afraid of the open pressure. My probelm with the 8019 on your cam is that the 8019 will have too much free travel left, even at .576 lift. It's just desgined for higher lift cams. Because it has more pressure it keeps mild cam lobes under control better at higher rpm but I think all that free travel will become a libality with a real aggressive low lift lobe. It can be made to work if the lobe has a real soft closing ramp. Spring surge is a difficult animal to tame and so far my best results have been by limiting how much free travel a spring has at max lift to around .100 or less. Incidently it only seems to be a problem on really huge mech rollers and really aggressive hyd rollers. I'm not sure how your XR288HR falls in on the "aggressive HR" side but if it's got any pop at all to it I'd err on the more conventional side of the way we've always sprung and ran hyd roller (ie 125-140lbs seat, 320-350lbs open and keep the RPM under 6500). BTW I've used the 8019 in (2) motors now. (1) lower lift mild lobe and (1) high lift aggressive lobe. Both with good results. If you want to see the specific set up and combination info that I used on them let me know, I'd be happy to share. Good luck with it. Will |
