broken valvespring.....again
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Senior User
Joined: Jul 2011
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broken valvespring.....again
my truck just broke its 3rd valvespring in 3 years. why the hell is it doing this?! my dad put a small rv cam in back in the 90s, but i wouldnt think that would be aggressive enough to break springs would it? even back then it broke a few. engine is a 400 BTW
Postmaster
Joined: Nov 2011
Posts: 2,553
Likes: 10
The OE springs in 400's are known to have zero capacity for a larger cam... even just a little bit larger will fail them.
You probably need new/different springs. If you know the cam, look it up or call the manufacturer for a spring recommendation. If not, you could look at the spring recommendation for a mild comp (eg 262) or the small Summit cam. Recommended springs for either of those two cams should work with a "mild RV" cam.
You probably need new/different springs. If you know the cam, look it up or call the manufacturer for a spring recommendation. If not, you could look at the spring recommendation for a mild comp (eg 262) or the small Summit cam. Recommended springs for either of those two cams should work with a "mild RV" cam.
Laughing Gas
Joined: Dec 2004
Posts: 754
Likes: 3
From: Idaho
I feel your pain brother my 400 started doing this 3 years after a rebuild broke 5 of them before i pulled it and stuck a cummins in it. never did figure out what was causing it ! mild cam new springs the hole nine yards when it was built, springs came in the cam set with lifters. measured everything trying to figure it out,stumped my dad who has been an engine builder for 40 years.
Elder User
Joined: Jan 2004
Posts: 767
Likes: 1
From: Franklin, GA
Upgraded cams need to be installed with new springs matched to the style of cam. If you are still using stock springs, get a set of valve springs designed to operate with whatever cam that's in the block and your troubles should go away. Not that bad of a job, just time consuming. You can do it in the truck without pulling the heads if you have an air compressor and get yourself a lever type spring compressor.
Postmaster
Joined: Jan 2013
Posts: 3,512
Likes: 3
From: Panama City
I dont suppose you know what installed spring height is supposed to be? Might just check all of them and see if there is a difference. Maybe turn engine over with new spring and see if it binding spring at compression.
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Post Fiend
Joined: Dec 2007
Posts: 8,521
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From: Lost
You may find that the spring seats need to be cut down a bit to get the correct installed height and prevent coil binding.
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Posting Guru
Joined: Jul 2009
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From: Schweinfurt Germany
I third this if you are having problem on spring best to check em all.
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