Comp cams XE266HR - Ford Mustang Forums : Corral.net Mustang Forum

 
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post #1 of 16 Old 02-22-2005, 08:51 PM Thread Starter
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Comp cams XE266HR

will there be any valve to piston clearance issues with a Comp cams XE266HR and stock pistons and Edlebrock rpm (190/160) heads with 1.7 rockers.

Basic Operating RPM Range: 1,600-5,600 RPM
Intake Duration 050 inch Lift: 216
Exhaust Duration 050 inch Lift: 224
Duration at 050 inch Lift: 216 int./224 exh.
Advertised Intake Duration: 266
Advertised Exhaust Duration: 274
Advertised Duration: 266 int./274 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.544
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.555
Valve Lift with Factory Rocker Arm Ratio: 0.544 int./0.555 exh. lift
Lobe Separation (degrees): 112

i dont want to valve relief my pistons when i do my H/C/I


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post #2 of 16 Old 02-22-2005, 10:45 PM Thread Starter
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post #3 of 16 Old 02-23-2005, 06:07 PM Thread Starter
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post #4 of 16 Old 02-23-2005, 06:21 PM
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That cam is intended for 1.6's. You're going to be looking at .590 lift with 1.7's and I don't know about PtoV on it but I think you're going to be hard pressed to find valve springs that will take that kind of lift. My options were limited even with .533 of lift.
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post #5 of 16 Old 02-23-2005, 06:24 PM
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Doubt it...but it wouldn't hurt to check. I run the 266 with AFR 165's at 56cc...I have .013 removed from the block...and run the thinner head gasket of the 2 or 3 that can be bought at local parts stores. No issues here.

'93 LX with IRS
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post #6 of 16 Old 02-23-2005, 08:40 PM Thread Starter
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Quote:
Originally Posted by Ebony93LX
Doubt it...but it wouldn't hurt to check. I run the 266 with AFR 165's at 56cc...I have .013 removed from the block...and run the thinner head gasket of the 2 or 3 that can be bought at local parts stores. No issues here.

is that with a stock short block?


the performer heads ahve a 60cc chamber, and im going to run locwire gaskets. so with 1.6 rocker i should have anly problems right?

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post #7 of 16 Old 02-23-2005, 10:20 PM
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My pistons have a slight dish to them ('91 pistons) so I'm sure that helps a bit. I can't say for sure if your combo will work but if I had to make a geuss...I still think you'd be alright.

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post #8 of 16 Old 02-23-2005, 10:54 PM Thread Starter
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thanks man, im gonna call comp cams, and summit and see what they say. hopefully i will get the same answers that i did from you.

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post #9 of 16 Old 02-24-2005, 08:53 AM
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I tell ya, that crower #15512 is a tough cam to beat, I cant believe more people arent using it.. and yes, I have tried it personaly in my own car..

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post #10 of 16 Old 02-24-2005, 09:08 AM
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If you're looking for a general guideline on whether the odds are good or bad that you'd have to cut for p to v clearance, I'm with others on the site - you'll probably be ok. But with MFE - w/1.7's that's a LOT of lift. You need to check for bind, and you need to be sure you've got enough spring pressure to manage the agressive ramp rates of that cam.

If you're looking for something as a substitute for actually measuring your clearance to be sure you're ok - there is no substitute. Every combo is different dimensionally even if the parts are the same. So you MUST measure if you want to know your clearance. And if you don't check your clearance, you're going on hope. That can prove expensive.


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post #11 of 16 Old 02-24-2005, 10:05 AM
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why go for the extra lift? The ebrocks don't really gain any flow from .500 to .600 anyway.....

I would bet even if you found springs that would work...you wouldn't gain any power anyway...so why bother?

If you want more from the cam go for a little more duration or a better designed ramp.


I talked to a very reputable cam grinder once and he told me that on my engine (331/AFR185) that with 1.7's on a tfs 2 cam I wouldn't see more than 1 or 2 hp gain from 1.6's. I had that engine dynoed and you know what...he was RIGHT!

1984 GT, 363 -RHS215 heads & Super Vic intake by MCRP, FTI cam, Carbureted, Glide, 4.30's, pump gas, street legal, N/A
Bests:1.35 60' / 6.21 /9.76 and 138.8 mph.
Thanks MCRP, UCC, FTI, Sepanek, Braswell, Racecraft, and Team Z
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post #12 of 16 Old 02-24-2005, 10:52 AM
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Some of the cam grinders will tell you that there can be benefits to increased lift beyond where the head appears to show max flow. When you do that, the cam spends a bit more time in the low and mid lift parts of the lobe (on the way to and from that peak lift). Sometimes the gain that occurs there is worth going with more lift. As with all this stuff, it's pretty hard to generalize. Only a really good modeler/model with good data could say for sure - but I think it would inaccurate to generalize that because there's no flow gain at the higher lift, that it wouldn't help to go there.

Michael Yount - Charlotte, NC - 82 Volvo 242 - 6.2L; '15 Fit; '16 CrossTrek

Last edited by Michael Yount; 02-24-2005 at 02:33 PM.
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post #13 of 16 Old 02-24-2005, 11:28 AM
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Well said Michael...and I understand what you are saying too.....

I retract my above statement, but I'll leave it there for learning purposes....that is why we're here right?

I guess it was sort of brainless for me to make a generalized statement based on one instance...

1984 GT, 363 -RHS215 heads & Super Vic intake by MCRP, FTI cam, Carbureted, Glide, 4.30's, pump gas, street legal, N/A
Bests:1.35 60' / 6.21 /9.76 and 138.8 mph.
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post #14 of 16 Old 02-24-2005, 02:34 PM
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Not brainless - we all generalize from time to time - me too. I just know when it comes to cams/heads/flow/power in a system that's as dynamic as an internal combustion engine there's hardly ever a one-size-fits-all-answer.

Michael Yount - Charlotte, NC - 82 Volvo 242 - 6.2L; '15 Fit; '16 CrossTrek
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post #15 of 16 Old 02-24-2005, 08:40 PM Thread Starter
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well the reason im using 1.7 is i have them and i dont really want to buy any new ones.

since MFE mentioned the lift. i did some research and i have found a few other cam with lower lifts but when used with 1.7 they will be what i want.

i realize i should check piston to valve clearance when i install the camand i plan on it. but i dont want to buy a cam that i cant use. this is why im asking if there is an issue.

here are the two cam i have been looking at.

Duration at .050: 220
Intake Valve Lift: 0.512
Exhaust Valve Lift: 0.533
Lobe Seperation: 112°

Duration at .050: 220
Intake Valve Lift: 0.512
Exhaust Valve Lift: 0.512
Lobe Seperation: 110°


i dont want to go to high on duration that is where i will have PtoV clearance problems are at least that is what i have been told and everything i think i know tells me.

next question is lobe separation. i was told that i need a 112-114 lobe separation to get good vacume but i noticed the "e" cam has 110 lobe separtion and my friend that uses that cam have no problems. is this right or was the guy mistaken.


thanks guys you have been a big help.

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post #16 of 16 Old 02-24-2005, 10:14 PM
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Look at Comps XE270HR 218/224 with .544 with a 1.7 rocker 112 LSA
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