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Author Topic:   Valve Springs
ryan
Dirt Freak

Total posts: 430
posted July 23, 2002 12:39 PM
I have been having problems with taking lobes of my cams(2 in 6 weeks or so)Last year I ran 441 heads with the same setup and had no problems this year with 462's I cant catch a break.I currently have a .508 lift cam with 550 springs on double humps and I currently have about .025 to .030 clearance between the coils. Is that to close, someone else on here said .060 minimum. Would I have to get .600 lift springs or what should I do.
I would like to know so if I need them I could order them in time to put them on for Sat.

birdcage
Dirt Full Roller

Total posts: 57
posted July 23, 2002 04:36 PM
RYAN
1 check the retainer to guide clearance(including valve seal also).
2 Make sure the rocker slots aren't to small and are hitting the studs(may need long slot rockers)I'm asumming stock type rockers!
3 Could be alignment problem with lifter bores. Is it the same block used before without any problems?
4 If your checking for coil bind with feeler gauges while rotating engine, that won't give you an accurate measurement. the dampner(if it has one) could be binding first and still have clearance between the main coils. You need to check the install hiegth(bottom of spring seat to the bottom of retainer). lets say its 1.800. Then collapse a spring in a vise(I figure you don't have the proper tools) and measure the colapsed height of the spring. Lets say 1.250. subtract the two and you get .550 so if the cams .500 you have .050 clearance. Just because the springs say 550 lift doesn't always get you that. If the spring was installed a 1.750 instead of 1.800 you'd only have .500 (coil bind).
This is basic engine knowledge. If this doesn't make sense I'd suggest going to a engine builder and take him the heads. It may not be a problem with the heads but that's the first place to check.
Also if it's a hyd and you where checking coil bind by rotating engine the lifters will bleed down just enuff that it won't have full lift and give you a false reading (more clearance than really have)

dirtbuster
Dirt Freak

Total posts: 353
posted July 23, 2002 08:53 PM
thats right ryan.. when i told you .060 clearance i meant total not between coils. birdcage described it exactly like i should have...sorry.

Are you using the 'Z' or 'Z28' springs. It sounds like you are. If so they are only good to about .480-.490. Even if they advertise tham as 550 it is always a good idea to check the coil bin height for your self.

Also check all the other things mentioned in the previous post any of them could be causing problems.

[This message has been edited by dirtbuster (edited July 23, 2002).]

ryan
Dirt Freak

Total posts: 430
posted July 23, 2002 11:50 PM
Thanks for your help guys I will check tommorrow.
Just to clarify its a solid cam with long slot 1.5 stock style rockers and yes this is the same block as last year. Whats a good .600 lift spring to get??

ryan
Dirt Freak

Total posts: 430
posted July 24, 2002 01:17 PM
Looks like everything is ok. Thanks again

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