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Old 06-29-2008, 03:13 PM
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Comp Magnum 280 vs XE274?

Trying to decide between these two cams for my 355 SBC. Currently, I have an Edelbrock Performer RPM, which I've just taken out.

Is there much of a difference between them? I'd expect the XE grind to provide slightly bigger numbers on the dyno, but I'm anxious about the very fast ramps and the strain in puts on the valvetrain.

Car weighs 2,500lbs, has 3.54:1 gears and is a stick shift. Not a daily driver.

Would I benefit from going any bigger on the cam? Currently running stock heads, but will prob either install Edelbrock Performer RPM's (170cc runners), or Holley SysteMAX (184cc runners) heads. Static CR will be ~10.2:1.

Thanks,
Ian.

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Old 06-29-2008, 03:37 PM
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Well I would go with the XE 274 it would give you better numbers wise and its more of a modern cam technology according to comp cams. The lift is a little more but not too much and lobe separation angle is the same so there would not be .much difference in sound at idle wise and they both would do about the same amount of wear on your valvetrain. I use to have a comp 292 wich is one step bigger then the 280 magnum and it was not bad. With that nice set up you got it would run good I am sure. I also read with recent problems with flat tappit cams going flat that comp said that they have had less xtreme energy cams go flat then the magnum ones so you might want to use that to decide with as well. Good luck I am sure it would do good with either one.
Eric
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Old 06-29-2008, 03:48 PM
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Funny, you never hear of such problems with cam life from people running Isky stuff. My machinist swears by them.
www.iskycams.com
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Old 06-29-2008, 06:08 PM
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Quote:
Originally Posted by F-BIRD'88
Funny, you never hear of such problems with cam life from people running Isky stuff. My machinist swears by them.
www.iskycams.com
I'm sure isky are great, and I would consider using them. However, the reason you hear of less problems with isky is because far less people use isky. On the other hand you hear so much about comp cams problems is because they are extremely popular cams. The sheer numbers of them out there is way, way more than isky. I'm sure every cam manufacturer has a couple go bad. When you sell 100x more than another company, it'll come up on these forums more often. The relative failure rate is hard to judge and so far I haven't seen any real data.
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Old 06-29-2008, 06:55 PM
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Quote:
Originally Posted by dh79
I'm sure isky are great, and I would consider using them. However, the reason you hear of less problems with isky is because far less people use isky. On the other hand you hear so much about comp cams problems is because they are extremely popular cams. The sheer numbers of them out there is way, way more than isky. I'm sure every cam manufacturer has a couple go bad. When you sell 100x more than another company, it'll come up on these forums more often. The relative failure rate is hard to judge and so far I haven't seen any real data.
Many pros use Isky stuff. Comp does a better job of marketing. They are much more agressive in advertizing and they do sell a lot of cams, especially to first timers, etc etc.
Other than issues with recent motor oil formulation changes and valve lifter
manufacturer QC problems in recent years since the OEM's stopped using and buying Flat tappet lifters:
Much of the problems with premature cam lobe failure are the result of trying to out do a established cam lobe design. If you read the fine print of the "EXTREME,,, VOODOO stuff you'll see that they warn that these designs definatly stretch the practical design limits for valve train life etc to get the extra poewr and or idle quality thye claim. Requireing bothersome engine breakin routines like swapping valve spring pressure or using low ratio rocker arms for initial eninge run in. The old pros like Isky and Crane have been there done that are far as stretching the limits of racing cam and valvetrain design. They know what works, what lasts in a certain racing and or street environment and what gets torn up before the finish line. Probabily got the broken parts and scared dyno room walls to prove it.
They (and Comp Cams) know from long experience what works on a typical street motor and will continue to make power 2 weeks, 3 months 3 years of use down the road.



A lot lot of other competing cam companies and big dollar pro engine builders use Crane's Computer Cam lobe design, anaylysis and prototypeing service to come up with or fix their own designs. Then put their brand name on the end of the finished product.

Comp cams does sell more cams. You put in a Isky cam and keep on going.
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