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Discussion Starter · #1 ·
COMP CAMS XTREME ENERGY XE270 CAMS FOR 1999 AND UP MUSTANG GT 4.6 MODULAR ENGINES.
Camshafts, Hydraulic Roller Follower, Advertised Duration 270/274, Lift .550/.550, Ford, Modular V8 SOHC, Pair Cam Style: Hydraulic roller follower
Basic Operating RPM Range: 1,800-5,800 RPM
Intake Duration 050 inch Lift: 234
Exhaust Duration 050 inch Lift: 238
Duration at 050 inch Lift: 234 int./238 exh.
Advertised Intake Duration: 270
Advertised Exhaust Duration: 274
Advertised Duration: 270 int./274 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.550
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.550
Valve Lift with Factory Rocker Arm Ratio: 0.550 int./0.550 exh. lift
Lobe Separation (degrees): 113
Intake Valve Lash (in): 0.000
Exhaust Valve Lash (in): 0.000
Computer Controlled: No
Grind Number: XE270AH-13
Quantity: Sold as a pair.
Notes: For 1999 and later performance improvements heads. Can also be used in 1998 and earlier heads with retainer to guide clearance modifications and Comp Cams valve springs.


would i need to swap out my springs in my 2001 pi heads to use these?
thanks
mike
 

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Discussion Starter · #3 ·
Notes: For 1999 and later performance improvements heads. Can also be used in 1998 and earlier heads with retainer to guide clearance modifications and Comp Cams valve springs
SO EVEN THO COMPCAMS SAYS THAT ,I STILL NEED SPRINGS
 

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yes
 

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it would be stupid to run ANY aftermarket cam without a higher tension spring. Infact. there is virtually no difference between the PI head and NPI head cams. If you think about it, those who have done a PI cam swap on thier 96/97 cars do so without spring lift issues.
 

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Discussion Starter · #8 ·
So Would Said Cam Require Piston Clearence Attention?
 

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joker77_2005 said:
So Would Said Cam Require Piston Clearence Attention?
You need to at least check for PTV clearance.The OEM valve "margin"(the lip around the edge of the valve) is really thick on the PI heads,so you're losing PTV clearance with that-some clear OK with that cam,some don't.
JL
 

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Discussion Starter · #10 ·
sounds like id be better off with a 262ah cam?
 

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joker77_2005 said:
sounds like id be better off with a 262ah cam?
yes. Its a good grind and a tune will take care of it. For personal reasons, Im not a comp cams fan - just a bad experience with them. Crower's Stage2 hi lift cam for the PI heads is a comperable grind.
 

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The Great Obucina said:
yes. Its a good grind and a tune will take care of it. For personal reasons, Im not a comp cams fan - just a bad experience with them. Crower's Stage2 hi lift cam for the PI heads is a comperable grind.
Agreeed.Either of those cams would work well,with minimal hassle.At the very least,PTV clearance MUST be checked to be sure it's in the safe range.
JL
 

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Refrigerator Raider Hater
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I agree with 262AHs with his current mods, but feel once he gets a high stall convertor, he would prefer the 270AHs. Most everyone has echoed what I said in response to your PM.


Johnny Langton said:
The OEM valve "margin"(the lip around the edge of the valve) is really thick on the PI heads,so you're losing PTV clearance with that-some clear OK with that cam,some don't.
JL
True, but it isn't any worse than PI heads on a PI block.
 

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GreenBird said:
True, but it isn't any worse than PI heads on a PI block.
Yep-and from what I've seen and discussed with others,this is a widely variable tolerance,and causes some issues.
JL
 

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Discussion Starter · #16 ·
Iassume that would mean to bolt everything down ,tension everything up and then spin the motor over by hand to check for ptv clearance?
or would i be missing a step in there?
btw i appreciate everyones help and assistants thus far
The Great Obucina said:
improper preparation leads to piss poor performance ;)

there isnt a reason not to spin the motor over to check for PTV.
 

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Johnny Langton said:
Yep-and from what I've seen and discussed with others,this is a widely variable tolerance,and causes some issues.
JL
JL, couldn't that margin on a PI valve be machined a bit thinner? I too was looking at that as I'm contemplating putting PI valves in an NPI head. Plus, it would be less weight to move up and down. Maybe even balance them all to the same valve weight. The PI seems to have a huge margin when compared to the NPI valve.
 

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joker77_2005 said:
Iassume that would mean to bolt everything down ,tension everything up and then spin the motor over by hand to check for ptv clearance?
or would i be missing a step in there?
btw i appreciate everyones help and assistants thus far

well, what you typed are the Cliff's Notes for what I mean.
 

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96SOHC said:
JL, couldn't that margin on a PI valve be machined a bit thinner? I too was looking at that as I'm contemplating putting PI valves in an NPI head. Plus, it would be less weight to move up and down. Maybe even balance them all to the same valve weight. The PI seems to have a huge margin when compared to the NPI valve.
You may be able to do that,but that could structurally weaken the valve.It'd probably be nearly the same cost to buy a set of SS replacement valves instead of modding the ones you already have. None of the aftermarket SS valves have that nasty margin on them.
JL
 

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96SOHC said:
JL, couldn't that margin on a PI valve be machined a bit thinner? I too was looking at that as I'm contemplating putting PI valves in an NPI head. Plus, it would be less weight to move up and down. Maybe even balance them all to the same valve weight. The PI seems to have a huge margin when compared to the NPI valve.

You can't swap the intake valve as the PI stem is longer since that portion of the chamber is less shallow. I can get SS Eaton valves for the PI or NPI heads if you wanted a set (PM me). Eaton is the same company that makes the blower for the Cobra.
 
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