spring specs for xr270hr hydraulic roller cam

[BBFORDFAN]

cant seem to find them. anyone know them off hand? 218/224@50,294/300 advertised duration,.521/.521 lift,110 lobe separation. thanks in advance

[blykins]

That cam would work with 140-150 seat and 350 open.  Real lazy cam and it won’t be a revver.

[fastf67]

http://www.compcams.com/Base/pdf/ValveSpringChart.pdf
Will give you info

[BBFORDFAN]

thanks. yes I know it wont be a revver but I didnt want one! its just a mild 390 and this will be perfect. thanks for the pdf file!!

[turbohunter]

Brent could you explain a bit what you mean by “lazy”?

[chilly460]

Not Brent but I’ve seen him use the term before, not necessarily in a way that condemns the cam.  I believe he’s referring to gentle, or lazy, lobe accelerations.  That cam has a pretty good amount of advertised duration for the lift and .050 duration specs, meaning it’ll have more overlap than a faster lobed cam.  Lazy lobes can be good in an FE as they generally are better for avoiding valve float.

[turbohunter]

Thanks Chilly
I didn’t think he meant “bad” cam, but if I remember correctly the ramps on that cam are pretty aggressive and noisy. I was just curious about the characterization and how that all related to lazy.

[blykins]

Thanks Chilly
I didn’t think he meant “bad” cam, but if I remember correctly the ramps on that cam are pretty aggressive and noisy. I was just curious about the characterization and how that all related to lazy.

I looked at the advertised duration that the OP posted in the first post to make my comment.   I don't think those are correct.  I just noticed that the thread title had XR270HR in it and if you look up XR270HR in the catalog, it's actually 218/224 @ .050" and 270/276 advertised.   

My spring requirements don't change just due to the small duration, lift, and low rpms, but the lobes could very well have a ticky, sewing machine sound to it as they are a little more on the aggressive side. 

[BBFORDFAN]

thanks. thats weird that the comp site lists 2 cams. one is the 294/300 duration and the other one is the 270/276 duration. thanks for all the help