x4 and 918s
Originally Posted by Nate_Taufer
Incorrect. The 918's are a lot more spring than people give them credit for. They originally were rated for .615 lift and can go even more if shimmed properly. They were down rated after comp released the 921's...probably just to sell more dual springs.
918's are a great spring in a nutshell.
Nate
918's are a great spring in a nutshell.
Nate
I just cant see running the risk of using USED 918's for a cam that is much to big for the X4. Also, just because people have run 918's with cams that exceed their stated tolerance it doesnt mean that its the best idea. Its just like the guys who have spin their stock enignes to 6800+ rpms or spray over a 150 shot on their stock engines. Sure people have done it, but it doesnt mean its the best idea for the life of the engine. Go with the dual valves springs and have the peice of mind that they wont be more prone to break under hard acceleration and higher RPMS.
Originally Posted by PREDATOR-Z
Shimmed 918's to .050 from coil bind will handle that cam with stock valves (titanium retainers a plus).
Most poeple do duals though.
Most poeple do duals though.
shim the 918s to within .05 of coil bind. i've read where people have had better results shimming 918s vs a dual spring.
just do as i oringally instructed nate, and you'll be fine.
just do as i oringally instructed nate, and you'll be fine.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Originally Posted by 98Z28MASS
But for how long? I dunno maybe im just one who would rather have valve springs that are overkill than ones that are borderline but when I spoke to a few shops about either running shimmed 918's or the prc dual valve springs they said they would recommend the duals if you going with an aggressive lobe cam (XER) and with lift over .610 lift. Not saying you cant run 918's shimmed on a fairly large cam, but I just figured that g5x4 would be really pushing it. Go with what you can afford though.
FYI 918 springs are THE best when it comes to harmonic control in valvetrain.
The trick is knowing what you're doing and matching components properly at proper install specs.
Bottom line the ligthest valves (like Katech 2.10) and titanium retainers and 918's, make for some of the best contoled high reving valvetrain without girdles.
Originally Posted by PREDATOR-Z
If you do your research, you'll find that there is such things as overkill on springs. (regarding your comment on XE-R lobes).
FYI 918 springs are THE best when it comes to harmonic control in valvetrain.
The trick is knowing what you're doing and matching components properly at proper install specs.
Bottom line the ligthest valves (like Katech 2.10) and titanium retainers and 918's, make for some of the best contoled high reving valvetrain without girdles.
FYI 918 springs are THE best when it comes to harmonic control in valvetrain.
The trick is knowing what you're doing and matching components properly at proper install specs.
Bottom line the ligthest valves (like Katech 2.10) and titanium retainers and 918's, make for some of the best contoled high reving valvetrain without girdles.
Well I understand overkill and I dont mean its better to run dual valve springs on a tiny cam or a moderate sized cam such as the ls6 cam over ls6 or 918 springs, id just rather have the peace of mind that I have valve springs up to the task with an aggressive cam like the g5x4. I havent had any experience with the 918's and I know you know/understand a lot about valvetrain components as i have read a bunch of your posts, so im sure then 918's can be run if setup properly so I stand corrected on that aspect. However is it easy enough to shim them correctly to run the 918's?
the g5x4 isn't all that aggressive compared to many of the new(er) cams utilizing lsk (and comparable) lobes.
lift is barely over .610 on the x4 using what is suspected to be xer lobes.
lift is barely over .610 on the x4 using what is suspected to be xer lobes.
i never said they were used 918s, i said they were free. $250 here, $250 there ends up adding up really quickly. thanks for the info preditorz, and nate taufer for the good info.
now the next question is, where do i get the shims at?
now the next question is, where do i get the shims at?
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Originally Posted by Cop Car
i never said they were used 918s, i said they were free. $250 here, $250 there ends up adding up really quickly. thanks for the info preditorz, and nate taufer for the good info.
.I know the 918's should theoretically hold a large cam, but I dont know why some people are willing to risk so much to save a few bucks. Does anyone even know the actual specs of the X4? I thought they were secret? That right there is enough for me to go wit the double springs. But hey, best of luck to you man
. 
Take the 918s.
Sell the 918s for 150.
Buy a dual spring for 250-600 depending on what you want.
Have peace of mind with that cam and a dual spring. Ive seen too many cars with dropped valves, broken springs, ect. Not to mention I have seen my fair share of dual spring equipped cars saved by the inner spring.
Yes, the 918 will hold the cam, no we dont recommend it. If you are asking how to shim it, I would get a drop in dual and not mess with it.
Louis
Sell the 918s for 150.
Buy a dual spring for 250-600 depending on what you want.
Have peace of mind with that cam and a dual spring. Ive seen too many cars with dropped valves, broken springs, ect. Not to mention I have seen my fair share of dual spring equipped cars saved by the inner spring.
Yes, the 918 will hold the cam, no we dont recommend it. If you are asking how to shim it, I would get a drop in dual and not mess with it.
Louis
