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Got a LLSR cam from cammotion in my 5.3 twin turbo setup. 8000 rpm shift, 25 psi. 650 lift. I originally had PAC springs with 200 seat pressure (1237x) in it that worked good. Went to change my springs and was going to put these same springs in but now I see they are not recommended for the street. Was going to do some street driving this year due to tracks being closed. Cammotion recommended a spring with 160 seat pressure, 500 spring rate, 1.000 coil bind. Does that seam a bit weak? I could probably shim them to 1.720 installed height which would be 200 seat pressure. Not sure if that would be to hard on the spring then? I think the cammotion spring is a PAC-1209.
 

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Any spring will live longest and have less chance of harmonics/spring toss shimmed to .060" from coil bind. That is pretty much the high performance standard.
 

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Discussion Starter #7
Thanks for your replies. I thought to at one time the 1237x springs were suppose to be ok for the street. Maby they were changed? I did phone PAC and they did recommended using the 1209 spring over the 1237. He said it was ok to shim it down to 1.710 installed height which would be .060 from coil bind. That should bring me a little over 200 pounds seat pressure. I wonder how the low lash solid roller lobes compare to hydraulic for valve spring pressure?
 

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Some hydraulic roller lobes can run solid roller lifters and some can't depending on the opening/closing ramp design. They can't really be directly compared in most cases because the hydraulic lifters are generally heavier than solid rollers, solid rollers usually have a lot more net lift and can tolerate much higher acceleration rates. The new Low Shock Technology lobes Comp Cams is developing for hydraulic rollers sound like they may have some merit in race applications. Billy Godbold has stated that they have seen in testing if they go easy on early lift area they can be much more aggressive later in the lift curve. I'm not sure how this will compare to solid rollers in overall power production but its generally accepted that the aggressive solid roller opening the valve early is a major contributor to power production. Boosted applications can get away with softer lobes by nature just as you can't run a hydraulic roller in Pro Stock. It's really apples to oranges if you are talking anything near max effort even for limited induction. I think the solid roller will always make more power simply because it's not as limited mechanically. There are some new advancements in lifter technology that will possibly make hydraulic rollers obsolete in high specific output applications. BAM Lifters that I'm a dealer for are now offering steel on steel bushing style lifters that use a DLC coated bushing. It is pressed on the stationary axle and the tool steel wheel rotates on the OD of the bushing riding on high pressure oil wedge. These seem to have eliminated any concerns about bushing wear and even then they are rebuildable if they are damaged from some other internal parts failure that damages the wheels. Isky is also still making improvements in bushing material composition and now offers a helical oiling groove that improves oiling between the bushing and axle. As to the root of your question, all I can say is it depends on several other factors with lobe intensity at the top of the list. So intensity, lift, base circle diameter, valve/spring/retainer weight, lifter wheel diameter, pushrod stiffness, pushrod/lifter/rocker weight also comes into play but is secondary to valve weight. So in the end it's a tough question with a lot of variables. Sorry for the long reply.
 
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