Heavy Z

Hello everyone, I am thinking of camming my 327/300 but would first like to find out what the stock cam specs are so I know what I'm working with. If anyone has info on the stock cam (lift, duration, lobe separation, etc.) I would really appreciate it.

Thanks, :cheers:

Heavy Z

lawcpi

Try this website for the info.
http://www.geocities.com/MotorCity/D...00/cmspec.html

Plasticman

Heavy Z,

My info says that you have a p/n 3896929 Hyd. lifter cam. This p/n has been changed to 14060651 (probably changed again from this#). The specs are as follows:

Intake: Duration 296 Deg. (195 Deg. @ .050" lift). Gross valve lift is .390". Opening @ 26 BTDC, closing @ 90 ABDC.

Exhaust: Duration 310 Deg. (202 Deg. @ .050"). Gross valve lift is .410". Opening @ 84 BBDC, closing @ 46 ATDC.

GM used very long clearance ramps for opening and closing, so the duration numbers are extremely skewed. Use the .050" numbers to compare aftermarket cams. Note that the exhaust has longer duration and higher lift, due to poor exhaust port configuration and exhaust system in general (was even worse with the "emission" heads of the 70's).

Hope this helps,

SWCDuke

The best cam upgrade is the L-79 cam and it is quite happy with the OEM valvetrain components as that's what it used.

Specs are about 222* at .050" 110 IC 118 LCA and gross lift is about .447"

If you want to go solid lifters the LT-1 cam is the winner, hands down.

If you install a more aggressive cam that drops idle vacuum below 14" be sure to install a NAPA/Echlin VC1810 vacuum can along with the more aggressive cam.

Duke

Heavy Z

Thanks to both of you, I'm all set!

Heavy Z

Heavy Z

Or the three of you, I should say. Below is the cam I was thinking. I've got Edelbrock performer rpm heads & intake, Holley 650 double pumper, rams horn exhaust manifolds, MSD. I want more power but don't want a big sacrifice in the low end, and I am not concerned with revving above 6000 rpms. Any ideas on the horsepower/torque gain from such a cam?

http://dab7.cranecams.com/SpecCard/D...1=Display+Card

If that doesn't work, just cut and paste this :
http://dab7.cranecams.com/SpecCard/D...1=Display+Card

Thanks,

Heavy Z

Maximillian

After a lot of researching, I went with 2.02/1.6 valves with a Comp Extreme Energy 268 cam. It's 224 intake and 230 exhaust on a 110 LSA and 106 intake centerline. Lift is .47 and .48.

I love this cam! IMO it's a perfect all-round cam, nice lope, reasonable low-end, tons of pull to 6000 rpm, and yes, I can still run my air conditioning :yesnod:

Oh yes, with this cam and head modification, while keeping absolutely everything else stock (even the original AFB), the engine made 383 hp@6080 at the crank! :cheers:


[Modified by Maximillian, 6:35 PM 8/30/2002]

SWCDuke

That cam looks very similar to the LT-1 cam, so I think it will work fairly well. Early exhaust phasing with a bit more exhaust than inlet duration and modest overlap are a key to obtaining a good street high performance 80 percent torque bandwidth of 2000 to 6000 with the OEM exhaust manifolds. Be sure you use their recommended spring.


Duke


[Modified by SWCDuke, 11:01 PM 8/30/2002]

Plasticman

HeavyZ,

What rear gear are you running? Or, I should ask, what RPM will the engine normally see at cruise? The Crane Cam listed has a pretty high "Cruise" RPM (3200 to 3800). Think you will see a substantial decrease in bottom end torque with this cam.

Plasticman

Heavy Z

I am running a T5 5-speed with a 3.7 rear. I generally cruise between 2,800-3,300 on the highway.

After reading your post and maximillian's recommendation, I'm sold on either the comp cams XE 268 (as max described) or the XE274. The dyno results look really good for both, but the low end in that XE274 is acceptable, and it's power curve - wow!), but that was in a 350. Since the horsepower stats on Max's cam are supposed to peak at 5,000 (in a 350) and his 327 is peaking past 6,000 rpms, maybe the 274 will be too much for my needs as I want to keep the redline around 6,000 rpms. Please check out the graphs below and let me know what you think of either cam.

XE268 http://www.compcams.com/information/...68H-10_001.asp

XE274 http://www.compcams.com/information/...74H-10_001.asp

Thanks! :cheers:

Heavy Z

Plasticman

Note that the cam results shown are with headers. You said your running Ram Horn manifolds, which are great but will still have less top end power than headers. Don't be dazzled by the high end numbers, especially when running on the street. Think the 268 cam far better for street purposes. Hate to see an engine overcammed (a balanced set of components are far more enjoyable).

Just my opinion,
Plasticman

SWCDuke

Forget about top and power and select a cam that yields 80 percent torque bandwidth from 2000 to 6000 RPM, and beware of excessive overlap with manifolds. It will just kill low end torque without making any more top end power than a cam with modest overlap.

If you want to really system engineer an engine, invest in a computer simulation program, and after you've run about two dozen cam grinds on the computer, you should get a feel for what makes a good high performance street smallblock, and the basic design bogey is the 80 percent torque bandwidth, not peak power at high revs.

Duke

Vetterodder

Don't discount the Crane 278 as it's an excellent cam. A friend of mine has it in his, otherwise stock, `67 SS350 Camaro and he loves it. Mild lope, excellent drivability, and a very noticable power improvement over stock. Don't be put off by those high cruise rpm figures. With 3.31 gears in the rear, he can mash the throttle at 2,000 rpm in 4th and it pulls smoothly. If you want more cam without too much more sacrifice in drivability, the Comp XE268 that Maximillian suggested is also an excellent cam and a notch up power wise. I love the XE274 in my 327 but those that want their Vette to idle like a Lexus wouldn't be so happy. With RPM heads, TorkerII intake, 700cfm DP, and headers, it idles well at 850 (will idle down to 600 but isn't happy) and 4th gear is usable down to 1,500 rpm. It pulls hard from 2,500 but really boogies from 3,500. Never been on a dyno but I'd estimate peak power at about 5,700 in my combination. I've never had a need to rev it past 6,200 but it was still pulling strong, though not as rapidly. Unlike the springs that come with many "bargain priced" heads, the springs on your Edelbrock's are more than adequate for any of the cams mentioned so far.

mrg

How about the Comp XE262 .. ? .. Power and torque fairly similar to the XE268 with perhaps a bit better throttle response with the higher vacuum signal in the XE262 ..
mrg

BigBlockThunder

Can anyone tell me what are the differences in the stock L79 cam, and the Comp Cam XE274H. What are the differences in specs, and more importantly, what are the differences in driveability from a gain loss perspective on HP, torque, rpm range, idle lope, etc... In a 1967 L79 engine.