Hey guys. I am in the proccess of replacing my Comp Cams XE274 in my 408 BB. For reasons unknown, it wiped the #7 exhaust lobe.:mad: I am going to replace it with a roller cam so hopefully it doesn't happen again. I am looking at the Comp Cams XE276 roller. Any thoughts on this cam? Should I go bigger? I would like to get as much HP out of the engine as possible. I was told that I could go a little more aggressive with a roller cam? I still want enought vac. to run a brake booster. The car (69 Camaro) will mainly be driven on the street. Car has 700r trans. with 4.10 gears. Engine is a 402 bored .030 over. 1966 396 heads (96cc closed chambered) large oval ports. Cast. # 3872702. Compression is 9 to 1. Full lenght headers. Holley 750 w/vac. secondaries, dual plane intake and HEI dist. Any suggestions would be appreciated. Thanks in advance.
Rick

You are a little low on compression at 9.0:1. If your using a .039 thick head gasket consider a .020" shim and bring the Static up to 9.5:1 and that's about as low as you want to go. Howver check your Quench try and get around .035" to .040".

I run the AR288-10 with 10.5 in a 460ci. not saying the XE276R-10 would not do the job for you but it has the "8" suffix and like mine is a CAST Crank and you can not run much more then 190lbs on the seat and no more then 500lbs open. Which in my opinion is suitable for me; however, if you are into Drag Race I would recommend a Billet Roller designated with the "9" suffix in the CC part number. Billet Cams allow you the run much higher Spring Rates but consider more seat wear. I like the looks of the 280A-R10 Billet Cam. You could run lots of spring pressure and get the revs but then you must have a Forged Rotating Assembly, Roller Rockers and Stud girdle. Also you require a Bronze Gear on the distributer which you must pay particular attention too.

You can have Comp Cams cut you a special profile and have a Cast Distributer Gear pressed on the Cam for a very reasonable price.

If you're using the car on the street you require a Roller Lifter with HIPPO (Hi-Pressure Pin Oiling) either from Crower or Isky Redzone - They are NOT Cheap.

Then again you could look at the Hydraulic Roller or choose an alternate Flat Tappet Design.

Any way another XE274 has failed - There has been a lot of these cams reported failed. How long before failure? We know the Ramp of these cams probably defy camshaft design but some are having good luck with them. Did you use oil with sufficient ZDDP? Castrol, Valvoline ... etc 4 Stroke MotorCycle Oils have more then enough ZDDP and better Shear Factor then Automotive Oils. One Cam I really like is the XM278H-12. Fantastic Torque right through the rpm range.

You have to consider that your Static compression really does not allow you to run much more then a 274 advertised duration and Retrofit mechanical rollers start at 280.

Suggest you play with a Software DCR Calculater and Comp Cams new SoftWare for Camshaft Selection.

Thanks for the reply. Sounds like you really know your stuff. My XE274 was broke in with the supplied cam lube. Ran it for about twenty minutes @ 2500rpm to break it in. I used Valvoline 30w heavy duty oil. Drove the car for approximately 10 miles when it started ticking. All the cam lobes and lifters look great except for the #7 exhaust. Both the lobe and lifter were toast.

comp cams tsk tsk
I stay away from them

Thanks for the reply. Sounds like you really know your stuff. My XE274 was broke in with the supplied cam lube. Ran it for about twenty minutes @ 2500rpm to break it in. I used Valvoline 30w heavy duty oil. Drove the car for approximately 10 miles when it started ticking. All the cam lobes and lifters look great except for the #7 exhaust. Both the lobe and lifter were toast.

When you say you used the supplied cam lube, was it liquid or the moly paste that you wipe on the lobes? I've owned a couple of comp cams and never had any problem with them (none of the XE series, though). However, I've always used the moly lube paste and EOS or the liquid equivalent suppiled with the cam for the break in.

If I remember correctly, is was a red sticky liquid. I didn't use EOS though. Next time I will.