PAC 1518 Spring Question
11-02-2013, 09:07 AM
#1
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PAC 1518 Spring Question Guys, I bought a used cam, used comp 7.425 pushrods, and a new set of PAC 1518 springs from a buddy. The cam is a Bullet and is 224 @ .050 with .560 lift. The springs are rated 130 @ 1.8 and 313 @ 1.20 and coil bind @ 1.140.
from all my searching it seams the installed height is actually going to be about 1.775 and will leave me .075 away from coil bind at max lift. Should I install a shim to put me @ .060 from coil bind or will I be ok? This will be going in an LQ9 with 317 heads and no mods if that matters.
from all my searching it seams the installed height is actually going to be about 1.775 and will leave me .075 away from coil bind at max lift. Should I install a shim to put me @ .060 from coil bind or will I be ok? This will be going in an LQ9 with 317 heads and no mods if that matters.
11-02-2013, 02:44 PM
#3
I'd error on the side of a little more than the recommended preload, than less than the recommended preload.
Go with a some .030" shims, that'll put you at 1.805", I know CompCams has them (pt# 4742-16 ) for less than $10..
Go with a some .030" shims, that'll put you at 1.805", I know CompCams has them (pt# 4742-16 ) for less than $10..
Last edited by 99Bluz28; 11-02-2013 at 02:58 PM.
11-03-2013, 09:22 AM
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If I am thinking about this correctly, adding shims will reduce installed height and increase spring pressures at installed height and max lift. I think the seat pressure will be fine, but am worried that I will not have enough max lift pressure.
11-03-2013, 02:04 PM
#5
just my .02 I think you are over thinking it a bit. That is a very mild lift and those springs are made to be .600 so id run them as is my z+221 cam has a .565/.560 and scoggin dicky says it can be run with ls6 springs. Im going to run prc 1518 wich are about the same as your pac's but much stouter than ls6
11-03-2013, 04:41 PM
#6
I don't what I was thinking, but it definitely wasn't correct. IMO, you be perfectly fine with the slight increase in spring pressure.
FYI, PAC racing has a valve spring rate calculator on their website, but it rounds it to the nearest 1/100th.
You're looking at about 136-139 lb seat pressure at 1.77"-1.78" installed height, and 312-315 lb at 1.21"-1.22" with
the valves opened .560".
Last edited by 99Bluz28; 11-03-2013 at 05:11 PM.
11-03-2013, 08:07 PM
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I think you are over thinking it a bit. That is a very mild lift and those springs are made to be .600 so id run them as is my z+221 cam has a .565/.560 and scoggin dicky says it can be run with ls6 springs. Im going to run prc 1518 wich are about the same as your pac's but much stouter than ls6
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11-03-2013, 08:08 PM
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My bad!
I don't what I was thinking, but it definitely wasn't correct. IMO, you be perfectly fine with the slight increase in spring pressure.
FYI, PAC racing has a valve spring rate calculator on their website, but it rounds it to the nearest 1/100th.
You're looking at about 136-139 lb seat pressure at 1.77"-1.78" installed height, and 312-315 lb at 1.21"-1.22" with
the valves opened .560".
I don't what I was thinking, but it definitely wasn't correct. IMO, you be perfectly fine with the slight increase in spring pressure.
FYI, PAC racing has a valve spring rate calculator on their website, but it rounds it to the nearest 1/100th.
You're looking at about 136-139 lb seat pressure at 1.77"-1.78" installed height, and 312-315 lb at 1.21"-1.22" with
the valves opened .560".
