PAC or Manley valve springs
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5,726 Posts
Can't go wrong with either set, but are they the correct ones for the app? Hard to say without more info......................
Bullet .800 lift solid roller with 1.8 rocker ratio for Ls na motor. I was told to run at least 250/750 spring pressures and 275/800 was optimum. I found a lot of choices in retainers for either spring because I need .100 tall retainer to bring up the install height up.
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10,229 Posts
is that the pressure Bullet recommended? would like something in the 300lb seat range.
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10,229 Posts
what dia.?
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10,229 Posts
the 1224 spring says its [email protected] im a dealer. in their book, they list their spring pressures at .050" increments.
if you can get a true 2" installed height, I would run the #1228.
PSI has a spring might work
1.625
With a standard retainer I was at 1.91 on the intake and 1.925 on the exhaust. And 1.965 on the intake and 1.980 with a .100 tall retainer. These measurements were with 1.550 spring retainers and .060 locator.
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10,229 Posts
you can get some spring locators in .045" too
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1,123 Posts
I just freshened up a set of heads with the 221424 and after 200 passes on .800 lift cam they were all within 10psi. that was set up at 2.000 and had 275/775# and really didn't lose any pressure. Course that was turning less than 8k. If you are doing a heads up deal turning over 8500 I'd probably opt for the PAC springs with their extra treatments. And then note like in a similar post on here that even though the pressure may decline, the springs may still break from fatigue so keep an eye on them
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2,859 Posts
Which one's will last longer before changing them out?
I've heard of PAC lasting longer and is a better quality spring. Personally don't have any experience with either so I really don't know.
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9,914 Posts
Ive used quite a bit of the manleys...(polished) version with VERY
good luck...lasted 2 seasons on my 404,,,, now they are on my
other 406 still going,, only changed them to feel better,,, were still
within 10 lbs of what i set them up @ and over the nose
good spring in my opinion.....so are the PACS
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6,509 Posts
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WARP, any update on that RO7 415 cui motor you guys did???.....really want to know
OH and X2 on the psi springs,,,, one of the best out there also......
OH and X2 on the psi springs,,,, one of the best out there also......
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10,229 Posts
Yes, i'm a PSI fan.
Just curious do you like PAC or PSI better. Or do you base it upon application like I have.
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10,229 Posts
would be both, depending also if both had a similar spring for the same application. Really like the PSI stuff, and in ten yrs, i've only broke one spring.
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