Internal Engine Cams | Heads | Rotating Assemblies

Comp XE278AH Cams for PI heads

Old 04-19-2006, 12:29 AM
  #1  
Staging Lane
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Join Date: Jan 2006
Location: Edinburg, Tx
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Question Comp XE278AH Cams for PI heads

the specs for this are

Duration @ .050
intake - 242
exhaust - 246

Lift
intake - .550
exhaust - .550

on a 113 LSA...

Is anyone running these cams ???.. any Piston To Valve (PTV) clearance issues with them.. just pulled out my motor and all pistons have the same dimple on them where the valve hit but no damage to valves.. stock PI heads and stock block on a 2002 GT.. running the comp beehive springs.. also what are best pistons to go with on the 4.6's.. i was thinking about Wiseco but they are for .030 over so dont really want to bore out my block since the machine shop said they would just have to hone the cylinders.. any thoughts or ideas???
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Old 04-19-2006, 05:08 AM
  #2  
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I'd make sure to have a machine shop check the valves before you reuse them, if they were being hit by a piston going around 2-5 thousand times a minute they are probably damaged, even if they are slightly bent it can throw off performance, and reliability.

Comp cam's are notorious for PTV because of the advance ground into the cam, and the quality control has let quite a few slip that were out of wack enough to make the car run worse. If you plan on reusing the same cam's I'd look into getting a degree kit, and checking the degree of the cam, it might be off enough to warrant either new cams, or getting adjustable cam gears to correct the problem and get your PTV issues lined out, especially on such a large cam as the 278

Pistons are really your choice, I have probe ultralight rods and pistons in my modular engine. and I have heard good things about mahle and manley.
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Old 04-19-2006, 08:13 PM
  #3  
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I hadn't heard of too much PTV on the 99+ pistons, as they are dished. There are many claims of PTV with these cams and NPI pistons as they are a true flat top.

I second Mahle pistons, I have heard great things about them!
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