shimming valve springs???
11-25-2005, 08:50 PM
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shimming valve springs??? I am going to be installing my trex soon... My question is do i need to shim my valve springs??? If so how do i know how much etc...
benefits,,, pros cons..
Thanks
dave
benefits,,, pros cons..
Thanks
dave
11-25-2005, 09:20 PM
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What springs are you putting in, and what is the install height? You will need a valve spring micrometer to check install height. Also with that large of a cam you will need to check for coil bind.
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11-26-2005, 11:20 AM
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At a bare minimum you need to put a degree wheel on and check PV clearance at 8-10* before TDC on the intake and 8-10* ATDC on the exhaust. I put a 228/230 .588/.591 in my car and only had .045 clearance and you need.080 minimum, so I notched. WE just put a Comp XER 242/248 .610/.615 in my friends car, which is almost exactly a TRex, and the engine wouldn't even turn over because of PV contact. This was tried without a head gasket just to see how close we were. Heads were AFR milled .034. I've said it a thousand times more guys are running around with much closer PV than they realize, and are just an over rev from a missed shift or valve float away from disaster.
11-26-2005, 02:42 PM
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It's always good to check PV for sure. A comp cam with similar specs to the trex is not comparing apples to apples because the duration and lift are similar, valve events is where they differ and the trex was designed to work with stock unmilled heads and stock gaskets without fly cutting. I definately agree with you though in that you really should degree the cam and check p to v for proper clearance 
Dan
Dan
11-26-2005, 05:41 PM
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It always amazes me how peple are eager to rip their engines without even realizing that PV clearance should be checked, or whether they should check for the right installed height...etc.
cam swap is NOT a bolt-on.
cam swap is NOT a bolt-on.
11-28-2005, 11:28 AM
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Originally Posted by bigdsz
The Patroit Golds will work well they have 135 lb at 1.80" install height and 385 lb open. They handle a .650 lift, with a 1.08" coil bind.
Where do i get the shims and do they go under or on top of the spring seat??
11-28-2005, 12:38 PM
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Man you need to use the search feature. You most likely will not need shims, but you should check the install height with a valve spring micrometer. The shims go under the seats. Installing a cam as big as the Trex means that you really need to check and recheck everything, because there is little room for error. Make sure you degree that cam and check PV.