Comp Cams High Energy 268 - any comments welcomed
 

I ordered the Comp High Energy 268 yesterday along with the other two kits that includes the rest of the valvegear matched to the cam (magnum roller rockers). Has anyone had any experience with this cam? It's going in my 81 350 with Carter 625 carb, Edelbrock Performer EPS intake, Davis HEI, Dynomax headers and stock TH350 with stock 2.82 rear end. I'm running stock compression of 8.2 :sleep: and was looking more for a torque boost than HP. Any ideas how much rear wheel hp/torque the cam and valvetrain alone is worth? Comp tech rep said the cam would make plenty of vacuum so I took his word on that.

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

The real question is how does the profile work with your low compression engine? I haven't looked at the specs in a while, but is it the best cam for a low compression engine? Many cams are designed to work with higher compression engines, in the very simplist of terms, the design of the cam lift and overlap bleeds off some of the compression. A cam of this type could actually produce lower performance in a car with low compression.
As I said, I'm not an expert by any means and am only reporting what I have read here and other places.

Re: Comp Cams High Energy 268 - any comments welcomed (Smokehouse69)
 

I'm with smoke house, I think that cam is going to kill you lower end with the 218/218 (at .050) duration. I had a 204/216 in my vette for a while and it had killer lower end but not much above 4000 rpm's. High duration means high power but also hurts low end.

Re: Comp Cams High Energy 268 - any comments welcomed (Fevre)
 

The High Energy cams are made to work with low compression engines like mine. They won't work with anything higher than 9.2. The engine won't ever get spun above 5500. I am looking for torque, not high rpm HP.

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

I used the XE262 in my build up. It has a lots of low end torque.

Dyno Results
Camshaft Part # 12-238-2 Designation XE262H-10
Duration @ 0.006" 262 / 270 Duration @ 0.050" 218 / 224
Max Lift w/ 1.5RR 462 / .469 Lobe Separation 110
Lobe ID#'s 5442 / 5201 Intake Centerline 106
Engine Type Chevrolet 350 Small Block
Bore 4.040" Stroke 3.480"
Displacement 356 Compression 9.25:1
Heads Dart S/R Intake Edelbrock Performer
Carburetor Holley #3310 Vac. Sec. Exhaust 1 5/8" Headers
Max Torque 415 ft*lbs @ 3700 RPM Max Power 348 HP @ 5300 RPM
Manifold Vacuum 17.5" Hg @ 800 RPM & 18.5" Hg @ 1000 RPM w/ no load.


I got this information right from Comps webpage. I couldn`t find any info like this for the High Energy cams though.

Re: Comp Cams High Energy 268 - any comments welcomed (Fevre)
 

I have this cam in my '74. The engine is a .020" over 350 with 882 heads (stock castings with a little work on the combustion chambers). The compression is about 9.4:1, and it makes plenty of low-end power, and plenty of top-end power as well. I think 8.2:1 is on the low end of the spectrum for CR with the 268H, but should be OK. I think Comp told me that more than about 9.5:1 compression would have been a bit much, or maybe they said 10:1, it's been a couple years. You could consider using a thinner head gasket to bump the CR a little bit, or milling the heads, or swapping in heads with a smaller combustion chamber volume.
I am about to add the Pro Magnum 1.6 rockers, and hopefully my AFR 190 heads will come pretty soon. The rest of my combo is Edelbrock Performer intake (soon to be RPM Air Gap), Hooker Super Comp headers, Speed Demon 650 mechanical secondary, MSD6AL with billet distributor. Also, I am running a 4-speed so low-end loss isn't such a big deal, just rev it up a little more before dumping the clutch.
My Gtech Competition just came in last night, I'll post some numbers when it quits raining around here.

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

I stand corrected!

Just seems like a lot of duration but I guess you have to factor in all the timing events. You might try a variable lifter to squeeze a little more out of the lower since you are down in the comp.

Let us know how it works out. If you are like me, once you get a high reving cam you forget all about low end. :cheers:

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

I have that exact cam in my, pretty much stock, '80 L48. I love it. I gives a slightly lumpy idle and kicks in really well at about 2500-3000 rpms. I do have a manual transmission, so I could afford to lose a little off the bottom. You might gave to go with a different torque converter to get it to idle in drive. Vacuum is not a problem. :cheers:


[Modified by The_Dude, 1:30 PM 2/20/2003]

Re: Comp Cams High Energy 268 - any comments welcomed (The_Dude)
 

I had it in my '68 when the 327 was in the car. Nice idle and rumble, plenty of vacuum, and all around great cam for a driver. :cheers:

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

Sounds like the HE260 might have been a better choice for you.

If you are set into using the 268, you might want to install it a couple of degrees (more) advanced to help a little on the bottom end. If possible, degree the cam in to make sure you're not installing it retarded. Also, you could run a little higher initial advance in your timing to boost the bottom.

A looser torque converter would also be something to consider. Hope it all works out for you. Good luck!

Re: Comp Cams High Energy 268 - any comments welcomed (nunus79)
 

It should be OK in your motor, but to bump up the bottom end, I'd have the heads milled to create smaller combustion chambers, or switch to different heads with smaller chambers. I'd personally take the heads off, bring them to a machine shop, and have them completely rework them for about 9-9.5:1 compression and better flow. If you install an aftermarket cam or heads by themselves, it will help, but if you install both at the same time, you will see a big power gain. If you keep the heads stock, they will be limiting your cam and the rest of the motor. The machine work for the heads should only run you about $600-$700, well worth it for the improvement it will make :yesnod: . Good Luck with whatever you choose :cheers:

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

I ran this cam in several cars. In my '76 C3, it replaced the larger duration 327/350hp and would run circles around it. Comp Cams used to recommend a 4 degree advance on it. Be sure to do at least that much. Much more will kill high rpm power but give a ton of torque.
http://www.sysmatrix.net/~jtreber/cc76.jpg

Re: Comp Cams High Energy 268 - any comments welcomed (nunus79)
 

Yes, HE260H would have been better for what you want, more TQ & less about 20HP.

4 degree adv. is ground in.

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

I ran the 268H in my 355 for almost eight years.Not a hint of what I'd call choppy idle,pulled to 5500 with the 3.70 rear,but I suspect you'll have trouble getting up to 5000 in drive with your gears.If you plan on gears later go ahead and install it,otherwise go with a smaller cam like the Edelbrock Performer. I ran one of those too,and it would smoke the 268H for low end torque running a near stock engine with 3.08 gears.
Remember it all in the combination! :yesnod:

Re: Comp Cams High Energy 268 - any comments welcomed (The Money Pit)
 

I'm going to do a 700R4 conversion later in the year :D so that will help with the LARGE - 2.82 - stock gearing. Both 1st and 2nd in the 700R4 are lower than what's in the stock TH350. Before I started this set of mods it was impossible to even turn the tires over with the stock power output. :cry

Re: Comp Cams High Energy 268 - any comments welcomed (914eener)
 

You should have mentioned the 700R4 to start w/ !
Sounds good. Lower rear gears still rec.! Cam will be fine.

:cool: