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FE Power Forums => FE Technical Forum => Topic started by: BBFORDFAN on June 14, 2019, 05:59:16 PM

Title: spring specs for xr270hr hydraulic roller cam
Post by: BBFORDFAN on June 14, 2019, 05:59:16 PM

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

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: blykins on June 14, 2019, 06:14:29 PM

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

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: fastf67 on June 14, 2019, 06:54:52 PM

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

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: BBFORDFAN on June 15, 2019, 07:11:39 AM

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!!

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: turbohunter on June 15, 2019, 10:47:13 AM

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

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: chilly460 on June 16, 2019, 01:16:42 PM

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.

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: turbohunter on June 16, 2019, 01:37:37 PM

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.

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: blykins on June 16, 2019, 03:24:05 PM

Quote from: turbohunter on June 16, 2019, 01:37:37 PM

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. 

Title: Re: spring specs for xr270hr hydraulic roller cam
Post by: BBFORDFAN on June 16, 2019, 06:02:23 PM

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