Is anyone using this cam?
CAM: COMP CAMS XE 268H
DURATION: 268/280-224/230@.050
VALVE LIFT: .477/.480@1.5
I am looking for a little lope on idle this is what the builder recommended will be running headers with 2-1/2 inch out the back.
Base L82

 

I'm running this cam, in fact a lot of people are running this cam on the forum...personally, I'm happy with the cam. Some people have had problems with break in on the Comp Xtreme Energy (XE) series cams, so make sure you talk to your engine builder about it. High zinc content oil appears to be necessary. Do a search on comp cams, and you'll find lots of threads.

Yeah, opening up of the exhaust really lets the cam do its work. I ran all last summer with 2" exhaust (budgeted enough for motor, not exhaust) and it was fun but not fantastic. Bolted on headers and ran them open a couple of times, and it made a world of difference. Can't wait to get my new exhaust welded up and really take the car out for a ride.

trw

 

How does it idle a little lope or not?

 

it has a slight lope to it at idle the car is not violently shaking or anyting but you can feel a little shake, i like this cam.

 

Was wondering if that cam is a midrange too upper rpm cam, or does it make some torque down low, like at 1200-2200 rpm??

 

The XE268 is a tame cam with some lope, before I switched to the roller cam I was going to go with the XE274 which was similar to my previous cam. The 274 has quite a bit of lope but not to much. All the hot rod guys always liked how the car sounded... Oh and she ran like stink... 13.7 @ 100 with stock 1.94/1.50 cast heads with 64 cc chambers 2.5" ramshorns manifolds... The new setup should be good for low 12's Dave..

Opps forgot the specs on the 274 it's 230/236 @ .050 and 480/490 lift... So not much bigger but a little..

 

go to comp cams and look at the spec sheet.....i think its 1800 rpm up and at 2500 rpm its all GO

 

Here's the link to the sheet that Bob was talking about

http://www.compcams.com/Technical/Dy...68H-10_001.asp

It's got a very nice torque curve.

trw

 

yeah thats what i was talking about....i can verify the numbers are accurate

 

Lots of discussion about the XE line on the Camaro site (camaros.net). Some believe a dual pattern isn't needed with headers and free flowing exhaust,..some believe the XE cams are too noisy (steep ramps cause the valves to slap shut often making a simular noise to unadjusted rockers),..and a few have experienced wiped lobes on break-in. Do a search on that site,.."noisy XE cam"..."dual pattern"..."wiped lobe",..etc, before you throw your jack down,..lots of info.

Good luck!

 

Thanks for all the information and input.

 

I was looking at the graph that 72 stingray owner provided for the XE268H cam. I decided to compare it to the XE262H which is what I am running. To my surprise the XE262H developed more torque and horsepower in their test. Plus it has more manifold vacuum. So why would anybody run the XE268H cam?

 

I think the 268 would need a bit higher compression ratio to perform better. One rag I read when researching my build got around 390 hp with the 268/vortec head and over 400 when they added the 1.6 rockers. I also wanted a higher rpm range.

 

You might be right about the compression ratio, however the 262 actually reached its max horsepower at a higher RPM than the 268 . . .5300 rpm vs 5000 rpm.

 

Choosing a cam is no easy decision. It must work with all the other components in order to maximize performance. I chose the 268 because it fit what I wanted to accomplish, was popular (before some of them wiped) and I found many magazines had build ups to compare(I am not one to reinvent the wheel). One of the biggest factors was this, taken from "Ryans car page". I am not a vortec fan so I used the old camel backs instead.

Combo 99.
Combo 99 uses Vortec heads and a bigger cam than Combo 98. The heads are pocket ported, and this helps the engine to make 409 HP and 427 ft-lbs of torque. The torque peak occurs at 3500 RPM, but the power peak is at 6000 RPM. The torque peak is only at 58% of the power peak, instead of the normal 70-80%.
Displacement: 350 cu. in.
Carburetor: Holley 750 double-pumper
Heads: GM L31 Vortecs, pocket-ported, with 1.94/1.50 in. valves
Intake: Edelbrock Performer RPM Vortec
Camshaft: Comp Cams Xtreme Energy 268 hydraulic, with 0.478/0.480 in. of lift and 224/230° of duration @ 0.050 in. of lift.
Exhaust: Hedman 1 5/8 in. headers and Borla XR-1 mufflers
Distributor: HEI
Comp. Ratio: 9.4:1

MAX HP: 409 @ 6000
MAX Torque: 427 @ 3500

That is why I chose the 268.

 

sounds like something is not the same in the two test engines...



well i just reviewed the test info and i see what you are talking about. i guess there is no real difference between the two

 

anybody have any info regarding the HE268 4 the big block....thanx..