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  #10 (permalink)  
Old 03-09-2008, 07:28 PM
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Join Date: Mar 2001
Location: E BRUNSWICK N.J. USA,
Posts: 3,841
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Default How do you break valve springs??

Barry R Like you and from my old race days in the mid 70's. I have worked on cars with 9,200 rpm motors both dirttrack and 1/4 mile. These are not FE motors. I have seen a number of guys break valve springs. Reason, the head builders can't measure the clearance between the coils on full lift, The coil binds and breaks the spring. Reason The dumb drivers overrevs the motor and bangs the motor off the rev limiter, piston and valve damage. Reason too heavy a valve train for the valve spring to work with, looses control and breaks spring. There was a whole bunch of stuff about the beehives breaking the bottom of the springs. I talked to the 2 senior engineers, both said the installer didn't measure for the correct bind clearance with a cam over the max safety limit. There where no cups for the bottom of the valve springs to sit in the pockets either. The spring where bouncing around in the oversized pocket. Since 95 all gm V6 motor are running these springs. I have repaired 2 motors from broken springs, one had 150,000 miles the other was a kid racing and over reved the motor. The single spring issue I can see. You could always add a small dampener inside the spring if you are that concerned. It still comes down to the right part for the right application. You can always get pistons with valve knockers to push the valve closed if you are that worried. Not sure how much this will effect the combustion chamber and power loss. You are only building motors with a 6,500 rpm limit. Anything more and you are wasteing motor for the EMC event. .120" is a safe coil bind, I have heard guys running as low as .070" and turning 7,000 rpm. These springs are going to break, it's a question of time, rpm and luck. Looking forward to seeing your new valve train setup, any pictures?? Rick L. Ps ran the car the other day, that stroker is something for bottom end torque. Tires don't stand a chance. Might advance the cam to remove a little of the bottom end. I wish I had the DannyBee timing setup on the 482 motor, 10 minute job and done. Later
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