Opinion on 272-272 Crane Energizer cam

[tony-muscle]

My 1971 Mach 1 351C-4V had the engine restored 12 years ago. I found the cam specs in the glove box. It is a 272-272 but I am confused about the lift. Is this a good cam for street use? what is your opinion about it? any issues?

 

[sicndhed]

Sharing opinions on cam choice is a great way to make enemies but I’ll take a shot.

This looks like a typical mild street performance cam. Though I’ve never built a Cleveland I believe that like a lot of engines of its vintage it responds well to having the exhaust duration 4 to 8 degrees greater than the intake duration (“dual pattern”). Older street cams tended to be “single pattern” like yours.

My tired eyes are telling me it has 112.5 degrees lobe separation angle and 7.5 degrees advance. Typical for a street cam. I’d expect it to work well with an automatic.

Is your lift question related to the dual numbers? The smaller number represents the lift produced at the camshaft lobe (this is the distance the lifter will raise). The larger number is the camshaft lift multiplied by the rocker arm ratio which is the distance the valve will open (if your rocker arms are the same ratio as listed on the card).

 

[Luke]

Wuss a mate of mine had a Xy falcon with that cam a 750 Holley on a old torker and a top loader it wasnt hard to live with quite fun really for what it was. I think a lot of it had to do with adding tongues/port plates

Sicndhed is right about clevos liking duel pattern cams and everything else he said is correct including the bit about a fast way to make enemies. It can be like telling someone thier kid is ugly Or kicking their dog

 

[tony-muscle]

Is the advertised lift then .302 or .524. One seems too low and the other too high.

 

[sicndhed]

I’ve never heard the term “advertised lift”. “Advertised duration” is the largest duration number on the card. It is typically the duration description that the cam makers use to describe their cams. Because there was no standard for coming up with that number it was difficult to compare cams from different sources. The duration as measured at .050” lift (measured at the cam lobe) is a meaningful way to compare cams from different sources. Even that is not a fool proof way to compare cams though. Over the last ten years or so cam profiles with faster valve motions have been coming out (Lunati’s VooDoo cams for example). The problem with moving the valve faster is there are limits to how fast the valve train can accelerate/decelerate before the motion become unstable. At some RPM limit the valve will no longer close as the cam lobe is dictating. This is valve float. Valve float will damage components in the valve train if allowed to go on for very long. In a severe case the valves can contact the pistons. Stiffer valve springs combat this problem but they can cause their own set of problems (bent push rods, rapid cam, lifter and valve guide wear). This is why most performance cams will have a recommended spring package to be used in conjunction with the cam.

Back to your question. In typical discussions about cams, the lift at the valve is usually discussed. With your cam it’s .524”. I suspect that it became the convention to discuss valve lift because till about twenty years ago most street cars used rocker arms with a ratio as designed by the factory. A typical street SBCs used their original 1.5 ratio. Then aftermarket 1.6 and 1.65 ratios became common for the sbc making talk about lift a little more complicated.

Pretty simple?

I glad you didn’t ask about modern oils and distributor gears……

 

[Mister 4x4]

This is basically the same cam I have in my 351C-2V. I have a CompCams Hi-Energy roller cam 274/274 (.566" lift) which works out to 214/214 @ .500". I'm also running the CompCams Hi-Energy 1.73 roller rockers. With a symmetrical cam (like both of ours), you should just have a nice solid, meaty idle - not choppy or anything like a race cam.

The advertised lift [on yours] is .524" with advertised duration of 272/272.

As I understand it, the ratio on the rockers is the multiple of how much travel they make (e.g.: if the cam bumps the pushrod up 1", the roller rocker itself opens the valve 1.73" - just a nice round number for explanation purposes).

Should be a pretty peppy set-up - mine has more throttle response than anything I've ever played with, and my gearhead/mechanic buddy is VERY impressed with how it behaves. I haven't actually driven the car yet (still putting it back together), but I believe everything so far bodes well for this thing being a beast.

Doc (73vertproject) has a very similar cam as mine (he was my inspiration, as a matter of fact), and his car is an absolute rocket now.

Hope this helps!

 

[Jeff73Mach1]

It is a very mild performance cam.

Duration is typically compared at .050 lift to get all of the lash out of the equation and allow comparisons to be more accurate.

Lift at the cam is multiplied by the rocker arm ratio to give actual lift 1.73 * .3027= .5236

Keep in mind that the Boss 351 had about .490 effective lift and was a solid cam profile, but being a solid cam, there's about .020 lift lost to valve lash

So that "mild" cam can help an engine make pretty good horsepower if the compression ratio is high enough.

I'd expect that cam in a 10 to 1 compression engine would be good for anywhere from 350-400 horsepower depending on intake, carb headers and ignition set ups. It should generate good vacuum for your timing advance, brakes and any accessories.

 

[Mister 4x4]

The CamQuest utility on the CompCams website helped me pick my cam and gave me a decent idea of what to expect with the other choices I've made. According to it, mine should produce somewhere around 406hp, with the things I've done (not taking into account the .060"-over bores) - and that's with 9.5:1 flat-tops.

 

[tony-muscle]

Thanks for the info guys. I am downloading the CompCams software so I can play with it.

 

[Mister 4x4]

It should give you a ball-park on what to expect, depending on the various things like: closed vs. open chamber heads, port & polish, headers, intakes, carbs & FI, etc. So you can kind of almost put together a shopping list of things to do, based on how you play with the filters to get the "virtual dyno" results you're after.

 

[jims72]

This site helps me with the numbers game. http://www.wallaceracing.com/camcalc.php