Vacuum/HP with Comp Cams xe/nx262 & xe268

[Shawn's 78]

Here's a question(s) and suggested feedback for those that run either Comp Cam XE268, XE262 or NX262.

First here is my set up:
78 L48
Cam (current stock) - well after this weekend, none. I collapsed a lifter and flattened a lobe on the #4 exhaust.
Heads: Edelbrock RPM
Intake: Edelbrock EPS
Exhaust: Supercomp Headers into MA's chambered exhaust
Carb: Holley street avenger (670cfm).
4sp / 3.36 gears
Stock bottom with good compression
NOS Top Shot (100hp). used 5% of drive time (some fun factor!)

I ran the numbers on CamQuest6 (comp cams free software) and cam up with the following (in order) comp cam XE262H, NX262H & XE268H. In other posts I see both XE's used, yet no comments on the NX.

So I would like to know a few things from those that use those cams:
1) what kind of vacuum readings are you achieving (Hg). Is it enough to run the brakes and headlights?
2) which is better for low end torque?
3) Has anyone used the NX262H?
4) Why do you like your 262 or 268?

I have the cam out and will be cleaning up the engine bay this weekend with plans to install the cam the following weekend (nice to have it up and running for Father's day!).
Your comments will help me with achieving the most in HP, low end torque and vacuum for the accessories.

Thanks in advance for your comments! :cool

 

[Vette79]

You will be good on vacuum. You are going to lose some low end torque regardless with which ever cam you go with but with the XE262 you'll lose less. Here is my recent Top-End Rebuild with the same cam: http://www.corvetteactioncenter.com/forums/showthread.php?t=103334

 

[Curtis]

the 262 will give you more torque than the 268 with only a small loss in top end power. Plenty vacuum .. 18 at 600rpm. Abundant low end torque slams you in the seat and keeps you there.

check this out. http://www.superchevy.com/technical...etebuilds_testing/0312sc_dm15_copy/index.html

 

[JohnZ]

The metal from that flat lobe is still in the oil - you're taking quite a risk by not tearing it down, checking all the bearings, and cleaning out the oil system.

 

[Shawn's 78]

JohnZ - before disassembly, I did a complete oil change. Then ran the motor with for a few minutes with new oil/filter then drained the oil, removed the filter, pulled the pan & pump. I Thoroughly cleaned out the pan & will replace the oil pump with one from Summit.
I checked the cam bearing (front) and it showed normal signs of wear for 90k miles. I'll pull one of the mains below just as well. I think I caught it in time (there again it's subjective to how long this has been going on).

Curtis - thanks for the article. I like the XE262 as well. It seems like the NX262 is the middle child between the XE 262/268. With my set up I desire to maintain some "neck snapping" torque in exchange of a few horsepower. 18hg is good for me.

Also, I forgot to mention I am using Scorpion 1.5 roller rockers with +.100 pushrods (if that makes any difference in comments posted)
Also, Has anyone used nitrous with any of these XE262/268 set ups?
Thanks
Shawn

 

[rbryce]

Shawn

I recently went through what seems like about 100 selections of possible cams for my new engine. I contacted Comp Cams tech line (hard to get thru but worth it) and each time I thought I had the right selection, they informed me of problems I would not have known about. When I told them that the cams they were recommending were not even in the list that Camquest had selected, their comment was that they (the tech's) were using Comp Cams best software, not Camquest, and they asked me just how good I thought a free cam program was going to be !!! Can't say yet how well their selection performs (not built yet) but I put their recomended cam into my engine builders software (Dyno 2000) and the results were very impressive. They had the answers for all of the question you asked about. If you call them, I would be interested in how it works out for you.

 

[Art Jett]

I have the XE262 in mine and love it. Nice choppy idle and plenty of torque.