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Head setup for xpz cam.

This is a discussion on Head setup for xpz cam. within the General W body forums, part of the Vehicle Specific Forums category; I have a xpz cam package with all the supporting mods in my 04gtp. Well my valve guides are going ...

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    SE Level Member gtpsgofast's Avatar
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    Question Head setup for xpz cam.

    I have a xpz cam package with all the supporting mods in my 04gtp. Well my valve guides are going to need replaced so my heads are off and the speed shop wants to know the specs for the cam so they can setup the propper spring/seat pressure etc. I have #130lb springs so does anyone know the info that I need to supply the speed shop with so they can properly set my heads up?

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    #AINTCARE Explicit_Spade's Avatar
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    Default Re: Head setup for xpz cam.

    Comp Cams - XPZ Cam Package #COMP-XPZ

    Modified heads are required with 130 or 150 pound springs. Peak lift of this cam with 1.6 ratio (stock) rockers approaches .570 on intake and .540 on exhaust.
    Intake and exhaust durations are purposely omitted. This is not to hide some secret duration numbers. It is because the duration numbers on most cams are listed at .050 lift and due to the highly unique nature of the lobes on this cam profile the numbers would not be comparable to other cams on the market. The cam spec card does not list Comp cams lobe numbers because they are highly custom. Please be aware of this before making your purchase.
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    Moderator BillBoost37's Avatar
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    Default Re: Head setup for xpz cam.

    Also... you should let them know that your springs are supposed to be installed at 1.800". If you didn't have the seats milled before, they springs aren't installed at the right height. Our heads with modded retainers only give us about 1.78X"


    If Dave feels 60% throttle is 100%, what does he tell his wife.

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    SE Level Member gtpsgofast's Avatar
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    Default Re: Head setup for xpz cam.

    The modified retainers. do they do just machine the face of the retainer to shorter the over all length? How much is taken off from the stockers. My retainers thickness or height is .311 thick? The fellow that installed my cam is no longer available to talk to so I'm just trying to figure out a few things that he did with the cam install. Now I have another shop redoing my heads because valve seals keep popping off. also I find out that all my valve guides are shot with only 67k on the orginal motor. I only have aprox 5k on this motor after the cam install and it never has been up to speed as far as performance goes with this xpz package. So it is definitely looking like the heads seem to be my major problem.

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