shim 918s with .563 lift
04-13-2011, 12:42 PM
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shim 918s with .563 lift 01 5.3l silverado
I have a TR224 .563 lift cam. I am about to install some new 918 springs. Assuming my install height is 1.8, should I shim? Comp Cams told me not to shim. Others have said shim .030
Any help is appreciated
Jason
I have a TR224 .563 lift cam. I am about to install some new 918 springs. Assuming my install height is 1.8, should I shim? Comp Cams told me not to shim. Others have said shim .030
Any help is appreciated
Jason
04-13-2011, 01:19 PM
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You should shim them at least .030". That spring is designed for .600" lift. It will live much longer when run closer to coil bind. Even though the TR224 has "only" .560" ish lift, it is a very aggressive lobe. I should know, I've installed more than anyone else...
Shane
Shane
04-13-2011, 01:43 PM
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You should shim them at least .030". That spring is designed for .600" lift. It will live much longer when run closer to coil bind. Even though the TR224 has "only" .560" ish lift, it is a very aggressive lobe. I should know, I've installed more than anyone else...
Shane
Shane
04-13-2011, 01:55 PM
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Guys, this will be my last post on this subject. I design and install valvetrains for a living. I have tested nearly every commonly used valvespring on our computerized spring tester and have used said springs with nearly every lobe combination out there. If you want to get the ultimate in performance AND longevity out of your valvesprings, you will follow my advice. In the thousand + cam installs I've done in the past 12 years, I have NEVER broken a valvespring when the valvetrain was set up correctly.
I have broken valvesprings before, that is how I've learned these tips.
Take it for what its worth. I am giving you FREE advice and have no monetary gain in this. Most engine builders won't tell you these things but as anyone on this site can attest to, I do know a little bit about this stuff, I shoot people straight, no BS.
Hope this helps,
Shane
I have broken valvesprings before, that is how I've learned these tips.
Take it for what its worth. I am giving you FREE advice and have no monetary gain in this. Most engine builders won't tell you these things but as anyone on this site can attest to, I do know a little bit about this stuff, I shoot people straight, no BS.
Hope this helps,
Shane
04-13-2011, 02:05 PM
#6
TECH Senior Member
Guys, this will be my last post on this subject. I design and install valvetrains for a living. I have tested nearly every commonly used valvespring on our computerized spring tester and have used said springs with nearly every lobe combination out there. If you want to get the ultimate in performance AND longevity out of your valvesprings, you will follow my advice. In the thousand + cam installs I've done in the past 12 years, I have NEVER broken a valvespring when the valvetrain was set up correctly.
I have broken valvesprings before, that is how I've learned these tips.
Take it for what its worth. I am giving you FREE advice and have no monetary gain in this. Most engine builders won't tell you these things but as anyone on this site can attest to, I do know a little bit about this stuff, I shoot people straight, no BS.
Hope this helps,
Shane
I have broken valvesprings before, that is how I've learned these tips.
Take it for what its worth. I am giving you FREE advice and have no monetary gain in this. Most engine builders won't tell you these things but as anyone on this site can attest to, I do know a little bit about this stuff, I shoot people straight, no BS.
Hope this helps,
Shane
Shouldn't your answer be more like shimm untill .xxx from coilbind? That IMO is a bit more correct. I've ran more agressive than TR lobes for thousands of miles and never broke one spring either as long as the spring pressures and install height were adequate for recommended lobes. So it is not NECESSARY to shim them if correctly installed at 1.800 height.
BUT it is possible that it may need shiming if it read more than 1.800 when dropped in, but that is another story.
04-13-2011, 02:37 PM
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Ok, I'll make one more post... Pred Z, you are correct, the more proper instructions would be to shim for somewhere between .050" and .075" from bind. The 918 spring and any spring for that matter has the coil bind calculation built in from the vendor. Since the 918 is rated for .600" lift, the spring will go more than .650" to bind. I have actually tested many sets of 918's and they will actually go .625" and still have more than .050" clearance... So, if you do the math (which I have and do every day...) The 918 needs to be shimmed to compensate for lifts signifigantly under .600" in order to get anywhere near its optimal distance from coil bind.
Just so you guys know, here at Thunder, we don't just sell parts, we do everything from CAI installs to complete race cars. I have just put together 3 420+ cu in LSx solid roller builds for a customer overseas. I am staking my money and reputation on my knowlege and skills to send these engines 12000 miles around the world. They HAVE to work... My customers depend on me to set this stuff up properly, that's why they buy an engine from me instead of locally. One of the engines we just finished is a 427 LSx block, 15:1 compression, SR 8000+ RPM with 2 stages of N2O (550 HP)
All of this R&D over the last 15 years has not gone to waste. When I sell a camshaft, I try to sell the proper spring, pushrod, and shim kit to give the customer the BEST POSSIBLE performance and longevity.
Do you HAVE TO shim 918's for the car to run? Absolutely not. Should you if you want your springs to last and perform to their maximum potential? Absolutely... period. end of story.
These are FACTS not conjecture.
Now I'm done.
Sorry /rant
Shane
Just so you guys know, here at Thunder, we don't just sell parts, we do everything from CAI installs to complete race cars. I have just put together 3 420+ cu in LSx solid roller builds for a customer overseas. I am staking my money and reputation on my knowlege and skills to send these engines 12000 miles around the world. They HAVE to work... My customers depend on me to set this stuff up properly, that's why they buy an engine from me instead of locally. One of the engines we just finished is a 427 LSx block, 15:1 compression, SR 8000+ RPM with 2 stages of N2O (550 HP)
All of this R&D over the last 15 years has not gone to waste. When I sell a camshaft, I try to sell the proper spring, pushrod, and shim kit to give the customer the BEST POSSIBLE performance and longevity.
Do you HAVE TO shim 918's for the car to run? Absolutely not. Should you if you want your springs to last and perform to their maximum potential? Absolutely... period. end of story.
These are FACTS not conjecture.
Now I'm done.
Sorry /rant
Shane
Last edited by XtraCajunSS; 04-13-2011 at 02:44 PM.
