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Valve Spring Question

Posted: May 31st, 2009, 9:53 am
by jffffl
I've searched and read any posts having to do with spring pressures, would like be at 110 to 115#
at installed height. The install height measures 1.60 and 130# and 300# at full lift with Comp 68-231-4
cam (stock cam reground). This is on my 7120 head, with P5249464 valve springs, P4452032
retainers, and P4529218 locks. The question I have is there any problem cutting the spring perches
down 0.040" to get that 130# down to 110 to 115#? Or what is the drawbacks of leaving the perches
alone and going with the 130#. I don't want to cut the valve guides, it will shroud the valve and loose
the benefit of the home porting that was done. My machinist is worried about cutting the perches
down, weakening the head.

Re: Valve Spring Question

Posted: May 31st, 2009, 10:30 am
by IH 392
jffffl wrote:I don't want to cut the valve guides, it will shroud the valve and loose
the benefit of the home porting that was done. My machinist is worried about cutting the perches
down, weakening the head.
Cutting the top of the guides and spring seats will in no way shape or form affect your port job, valve shrouding is in the combustion chamber and cylinder not the port, and I don't think that I'd worry about cutting .040" off of the spring seats either.

Re: Valve Spring Question

Posted: May 31st, 2009, 2:27 pm
by SIXPAK
.040 on spring seats is not an issue at all. Cut away without worry.

Re: Valve Spring Question

Posted: May 31st, 2009, 8:36 pm
by SilverXJ
I have had my valve seats to lower the spring pressure as well. However, keep in mind that if you are using new springs they will loose some of their seat load when they are run.