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#1
03-20-2016, 12:58 PM
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Valve Spring Diameters and Spring Seats
It's been several decades since I had a Pontiac (was messing with Mopars) but I saw the light and returned to Pontiac, buying a '68 GTO a few years ago. It's been modified by previous owners so originality is long gone. It has a '69 Grand Prix 428 with the '68's water pump assembly, a set of 6X-4 heads and an Edelbrock intake with MSD rtr distributor; with the Hurst shifted TH400.
Because the purchase of the '68 ate of most of my car funds, I have to approach things carefully. And my wife does not want another disabled car in the garage while I raise funds to finish things (sound familiar, anyone?). So I am seeking answers first before I start anything. I've determined a cam change would help the car and have a Crower cam in mind. I am planning to use Crower's 68404-16 valve springs. These springs are 1.405 inches in diameter and I understand stock Pontiac springs are 1.384" in diameter.  Many folks here seem to use the 68404 spring. Does the 6X-4 head spring seat accept the 68404 spring OK as is OR does the spring seat need to be machined out? If it needs the diameter widened, how deep should the cut be?I know this is a novice question but I appreciate all help...Thanks All! |
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#2
03-20-2016, 04:31 PM
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I am pretty sure the crower 68404 valve springs will fit without any machining and you can use your stock retainers and locks. Just my 2 cents.
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#3
03-21-2016, 06:56 AM
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Do not reuse your stock valve locks when far better ones can be had for under 20 bucks !
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#4
03-21-2016, 09:33 AM
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Thanks, all. It sounds like I can do this job easier and cheaper than I hoped.
Using the Crower 68404 valve springs and existing retainers and Crane or Comp valve locks from Summit, we'll be good to go top side. Appreciate it. 
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#5
01-16-2019, 10:41 PM
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springs
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