T-Rex with unmilled 5.3L heads?
09-12-2004, 11:48 PM
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T-Rex with unmilled 5.3L heads? Piston to Valve Clearence, is the cam to Big? I love everything about it and I want it but I just wanted to ask? heads are unmilled 5.3L with LS6 vavles. I have heard that the cam works well with stock heads but these are ported so should be better if it fits right?
thanks
mike
thanks
mike
09-13-2004, 01:43 PM
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The TREX should fit with un-milled 5.3l heads. If the heads haven't been milled the valve drop should be the same as stock, and in that case it will fit just fine. The chamber is smaller with the 5.3l head but not in a way that would affect P/V clearance. In any instance however it is always a good idea to double check if there are any doubts.
09-13-2004, 02:20 PM
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Originally Posted by TR
SPECS
Thunder Racing TRx V.2 - 242/248 .608/.612 110lsa +2
Piston to Valve clearance
When going with a cam of this size, piston to valve clearance becomes more of a concern. Both of these cams are well within the spec of allowable clearance with stock heads and stock shortblock. They are, however, on the tight side of the spec, but definitely something that can be used with the proper attention being paid to the install (intake centerline) and valvetrain selection.
The cams have the following PtV with a stock cylinder head (stock valves, stock valvejob, no milling), '98/'99 GM graphite gasket (.053", compressed), stock shortblock (pistons .007" above deck), and a 108* intake centerline:
V.2: Intake .070", Exhaust .090"
For those that feel that this is too tight and are uncomfortable with this clearance, we do offer the ISKY flycutting tool which will make valve reliefs in your stock pistons. The heads do need to be removed to perform this task, so be prepared to purchase new gaskets and bolts. You can notch the pistons with the motor still in the car. You can also just select a smaller camshaft and not have to worry about any of this.
The pistons in my car are not notched and I have had no problems with any PtV.
Thunder Racing TRx V.2 - 242/248 .608/.612 110lsa +2
Piston to Valve clearance
When going with a cam of this size, piston to valve clearance becomes more of a concern. Both of these cams are well within the spec of allowable clearance with stock heads and stock shortblock. They are, however, on the tight side of the spec, but definitely something that can be used with the proper attention being paid to the install (intake centerline) and valvetrain selection.
The cams have the following PtV with a stock cylinder head (stock valves, stock valvejob, no milling), '98/'99 GM graphite gasket (.053", compressed), stock shortblock (pistons .007" above deck), and a 108* intake centerline:
V.2: Intake .070", Exhaust .090"
For those that feel that this is too tight and are uncomfortable with this clearance, we do offer the ISKY flycutting tool which will make valve reliefs in your stock pistons. The heads do need to be removed to perform this task, so be prepared to purchase new gaskets and bolts. You can notch the pistons with the motor still in the car. You can also just select a smaller camshaft and not have to worry about any of this.
The pistons in my car are not notched and I have had no problems with any PtV.
However we all know that T-Rex has been known to show up with "slightly " different specs on cam cards and they are not consistant in their grind.
I'm not bashing mind you just warning that to make a statement like Geof did "should fit" doesn't mean "does fit" and the only way to find out is to install it and use a dial indicator to measure PV clearances. This a cam that has VERY tight clearances.
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09-13-2004, 05:34 PM
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Originally Posted by SS1421
Hey Mike have you seen/heard/ridden in Brandon's SS with the T-Rex yet. YIKES!!! Hope this works out for you because that is one wicked bumpstick.
Trace.
Trace.
09-13-2004, 09:52 PM
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Originally Posted by jerflash
they will fit under stock 5.3 heads but when you got to bigger valves you need to notch the piston
09-14-2004, 12:39 AM
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Originally Posted by MikeB.RamAir
hey Trace, nope haven' heard Brandon's car, but I did see it with the rear getting worked on, heard the vette and GTO very nice!! I hope it works out too! if not the 231/237 is a nice size as well. any way it works I want some big power, how does a 10sec car sound!
09-14-2004, 09:03 PM
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I'm in the process of a full rebuild on my motor, and I'm using a "thick" T-Rex cam (249/244 .610/613 109). My new pistons have -2cc valve reliefs in them and I'm going with a 6.125" rod. I hadn't thought much about it, but had eliminated the idea of a 5.3 head. After reading this, however, it's got my interrest. Could the notched pistons clear an unmilled 5.3 head on my application?
