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question about valve springs and cams
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Posted by: maddmatt02

I was looking today at performance parts for the 450r, and the hot cams stage 3 cam shows .409 lift on the intake side, and claims to use the factory valve springs.

I was on the web cams site, and the cam that has a spec of .400 intake valve lift recommends a performance valve spring kit, and the cam that has a intake lift of .415 says requires a spring kit?

I started thinking that maybe it had something to do with the duration, like the hot cams valves were open longer and in turn set the valve back down slower/over a longer period of time and would be less prone to valve float, but looking at the specs, the web cams have a longer duration?

is web being overly cautious, or is hotcams being a little bold in saying its fine with stock springs?

is the stock setup prone to failure?

would it be safe to run stock springs? i was figuring on running a performance spring kit anyways, looking at the kibblewhite kit.

is there another manufacturer youd reccomend and at a cheaper price and still good quality?

thanks

and no i dont have a 450r right now but I better within the next 3 months.

Posted by: chad502ex

quote:
Originally posted by maddmatt02
I was looking today at performance parts for the 450r, and the hot cams stage 3 cam shows .409 lift on the intake side, and claims to use the factory valve springs.

I was on the web cams site, and the cam that has a spec of .400 intake valve lift recommends a performance valve spring kit, and the cam that has a intake lift of .415 says requires a spring kit?

I started thinking that maybe it had something to do with the duration, like the hot cams valves were open longer and in turn set the valve back down slower/over a longer period of time and would be less prone to valve float, but looking at the specs, the web cams have a longer duration?

is web being overly cautious, or is hotcams being a little bold in saying its fine with stock springs?

is the stock setup prone to failure?

would it be safe to run stock springs? i was figuring on running a performance spring kit anyways, looking at the kibblewhite kit.

is there another manufacturer youd reccomend and at a cheaper price and still good quality?

thanks

and no i dont have a 450r right now but I better within the next 3 months.

inquizitive.

cam ramp rate is really what determines the need for stiffer valve springs.

Some of the Web Cams have reduce base circles, whereas the HCS3 is a full base circle like stock.

Reducing the base circle of the cam allows the valve to be lifted from seat much faster then a full base cam with with the same lift.

the faster the valve lifts from seat the more the follower has a tendency to loft over the nose of the cam profile. Stiffer valve springs have a higher rate. Over time, a spring will become softer if the spring gets hot on fast ramps. If the spring can not disapate the heat, it become fatigued. That spells catastrophic conditions.

Posted by: maddmatt02

so is the HCS3 safe with the stock springs?

I was also planning on a rev box, I wouldnt be running it very often in those last thousand rpms, but it would be when I was trying to waste that yfz I line up next to.

should I just play it safe and get the spring kit since not only will there be more lift, but it will also be revving a grand higher now and then?

also I saw on the other thread the pic of your piston. yours is 12:1 right? stock on 06-08 is 12:1 right. what was 04/05 stock cr?

and does that make the main benefit of your piston that it is lighter?

is stock a 2 or 3 ring design?