View Full Version : Down to 2 cams... Which one?


71cmro
02-16-2011, 10:41:31 AM
Probably not much difference in them but I figured I would ask those that know. Thanks.

Comp Cam 268h vs Comp Cam 270h

Engine specs
350 4 bolt main
Eddy Vortec Intake
Full length headers
4bbl Quadrajet

Heads
Vortec cast iron 170cc Intake ports
64cc combustion chambers
1.940" Intake/1.5" Exhaust
.475" max lift

5spd540
02-16-2011, 11:30:23 AM
the270 sounds better but the 268 is mire street friendly

5spd540
02-16-2011, 11:31:01 AM
What do you have for a converter

Cardinal
02-16-2011, 11:31:12 AM
4bbl Quadrajet I am a die hard fan of the Qjet BUT it HATES big cams as it requires good vacuum at idle. So, I would choose the 268H because it is going to produce slightly more vacuum at idle.

We've run that cam on a bunch of stock engines and quite honestly, I think it's about the best street cam you can use.

Remember: less is more ESPECIALLY with cams. The BIGGEST mistakes are putting too big a cam and TOO big a carburetor. It's know as the BIBS: bigger is better syndrome. EX: if a 600 carburetor is good, then a 1150 HAS to be better. NOT!

onovakind67
02-16-2011, 11:54:06 AM
I am a die hard fan of the Qjet BUT it HATES big cams as it requires good vacuum at idle. So, I would choose the 268H because it is going to produce slightly more vacuum at idle.


What characteristics of a Q-jet require high vacuum at idle?

Todd80Z28
02-16-2011, 12:12:50 PM
Both are single pattern, and IMO, both are wrong for the Vortec heads.

mrvedit
02-16-2011, 12:43:05 PM
You might consider the XE268H which is dual pattern. However it has .520" of valve lift. I don't have experience with Vortec, but I understand it is easy to modify Vortec heads to support that much lift.

Just checked - the 270H has .51" of lift, while the 268H has only .454 of lift.

onovakind67
02-16-2011, 01:01:31 PM
You might consider the XE268H which is dual pattern. However it has .520" of valve lift. I don't have experience with Vortec, but I understand it is easy to modify Vortec heads to support that much lift.

Just checked - the 270H has .51" of lift, while the 268H has only .454 of lift.

The 270H has only .470" of valve lift with 1.5:1 rocker arms.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=78&sb=2

71cmro
02-16-2011, 01:27:25 PM
Both are single pattern, and IMO, both are wrong for the Vortec heads.
Please explain. Many folks on here recommended these cams for vortecs last year when I bought them.

71cmro
02-16-2011, 01:32:37 PM
What do you have for a converter

Stock converter. From my research both will work with the stock converter but the 270 requires a 4bbl carb and headers which I have.

onovakind67
02-16-2011, 02:16:14 PM
Please explain. Many folks on here recommended these cams for vortecs last year when I bought them.

Here's how Isky explains it:

http://www.iskycams.com/techtips.php#2003

450bench
02-16-2011, 02:48:54 PM
270h

BondoSpecial
02-16-2011, 02:57:45 PM
with a stock converter, the smaller.

bigbad79
02-16-2011, 09:51:10 PM
Both are single pattern, and IMO, both are wrong for the Vortec heads.


Xe268 is dual pattern.....but I would chose the xtreme energy over magnum any day because it is newer technology and more street friendly. The idle will be less aggressive than the 270, but will produce more low end torque and horsepower.

Todd80Z28
02-16-2011, 10:06:47 PM
Please explain. Many folks on here recommended these cams for vortecs last year when I bought them.IIRC, the Vortecs flow somewhere around 240cfm intake, 150cfm exhaust. That's under 70% E/I ratio, so they could probably use some help on the exhaust side. Isky would probably agree, based on the numbers.:)

For clarification, you said 268H and 270H, so I think of the

Comp Magnum 268H- 218*/.454, single pattern.
Comp Magnum 270H- 220*/.470, single pattern.

If you were talking about the XE series, which is dual pattern, then never mind.:)

XE262 at 218/224, .462/.469 would be a good start, IMO.

CamaroMan79
02-17-2011, 12:28:51 AM
You might consider the XE268H which is dual pattern. However it has .520" of valve lift. I don't have experience with Vortec, but I understand it is easy to modify Vortec heads to support that much lift.

Just checked - the 270H has .51" of lift, while the 268H has only .454 of lift.

The XE268H has .477" / .480" lift. not .520"

Cardinal
02-17-2011, 12:46:06 AM
You know, the more I think about it and the more people that have left their opinion on what you should or shouldn’t be putting in for a cam leads me to tell you to call Comp Cams and ask them. How better to get the best cam than to call the people who design and manufacture the cam!

IF it were me, I’d also call Crower and Isky to ask them what they would recommend.

71cmro
02-18-2011, 06:40:07 AM
Will I have a problem with the XE268H intake lift of .477 and exhaust lift of .480 since my lift is a max of .475?

5spd540
02-18-2011, 06:48:29 AM
No you will be fine

hhott71
02-18-2011, 09:26:32 AM
2 identical cars eacxh with one of those camshafts.
The performance fuel ec onomy differences would be so subtle that it would almost not be worth mentioning.

The 270 should be quicker by a little bit
'The 268 should get a smidgen better economy.

It all depends on the rest of the combo like gearing and stuff,, 4.10's,,, 3.42's or 2.41's?