Valve Spring Question
Valve Spring Question
I'm going to be running the ZZ3 camshaft in my L98. I found some springs from GMPP that seem to have the right pressure and installed height. The only question I have is if they will fit without machining the spring seats. The stock springs are 1.250 in diameter whereas these are 1.273. Will these fit the stock spring seats? The part# for the springs is 3927142. Any helpful info would be greatly appreciated!
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
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Pat,
It really depends on the heads. Some factory heads will accept springs up to 1.330" without further machining, and some are so close to the 1.250" size you wonder if the stock springs will fit. You really should remove a spring and check the seat machining to see if the current seats are adequate. There's a good chance that they are large enough for the extra 20 thousandths required by the springs.
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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
Adobe Acrobat Reader 4.0
It really depends on the heads. Some factory heads will accept springs up to 1.330" without further machining, and some are so close to the 1.250" size you wonder if the stock springs will fit. You really should remove a spring and check the seat machining to see if the current seats are adequate. There's a good chance that they are large enough for the extra 20 thousandths required by the springs.
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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
Adobe Acrobat Reader 4.0
Supreme Member
Joined: Jul 1999
Posts: 18,457
Likes: 16
From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
I would avoid the GMPP springs if possible. IMHO they are over-optimistically rated. They are basically 1.25" springs, which no one else on the planet will recommend for use at over .500" of lift.
Comp has a new spring, part # 982, that is conical: 1.25" at the bottom so it fits the heads without machining, 1.45" at the top, so there's enough material to bend over and over again like springs do and not break. I would strongly suggest you get those and the retainers to match.
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"So many Mustangs, so little time..."
Comp has a new spring, part # 982, that is conical: 1.25" at the bottom so it fits the heads without machining, 1.45" at the top, so there's enough material to bend over and over again like springs do and not break. I would strongly suggest you get those and the retainers to match.
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"So many Mustangs, so little time..."
Hey RB, I have to admit I've sort of had reservations about the GMPP springs too. I've seen those conical springs, and they might be the way to go. I've also been considering the H-11 tool steel springs offered by Crane. I guess I'm trying to find the best compromise between not having to spend a fortune on the springs and having the spring seats machined.
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
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