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what makes a mild cam not a mild??

20K views 25 replies 16 participants last post by  atle 
#1 ·
:D so just reading and thinking... alot of guys mention they have a mild cam and such. i was wondering is there a range that makes a cam a mild cam vs. a radical cam?

so my cam is, is it a mild or something else?


  • Advertised Duration (Int/Exh): 267/273
  • Duration @ .050 (Int/Exh): 237/243
  • Gross Valve Lift (Int/Exh): .639/.655
  • LSA/ICL: 110/106
  • Valve Lash (Int/Exh): .018/.018
  • RPM Range: 2500-6600
 
#3 ·
IMO,by looking @ your cam specs I'd say your on the mild/wild border line.
Alot has to do with the rest of the engine combo....what is WILD in a 'race only' 396 will be a kitten in a 572.

& as Vince said....personal perception.
 
#4 ·
Thats a good street cam. To me mild is when it can support power brakes and can still idle below 1000. I bought a 231/239 @.050 .535/.550 hydro roller for my 350, because it has power brakes. I expect this cam to work just fine. Now my Chevelle has a 275/287 @.050, .788/.765 and idles at 1600.
 
#5 ·
For a solid (roller?) cam in a big block, I'd call that moderate on it's way toward radical...depending on how it sounds at idle.

Like Vince said, it's perception... and I'll add "opinion."

To me, a "mild" cam is bigger than stock but still works with a stock torque converter and a "radical" cam has a really wicked idle at 1000 rpms.
 
#9 ·
====================

You can have 2 cams with same approx dur @ .05 ,lift etc but the cam with a 112 LSA will sound milder at idle and lower engine speeds then the other cam with a 108 LSA.

So mix that with maybe a smaller cid motor too and thats why you heard wicked sounding cams that were smaller spec'd then your's.

Scott
 
#11 ·
Give Mike Lewis @ Wolfplace a call:

A nice cam is race-only.
A mild cam is primarily strip but might see some street action.
A "weenie" cam is suitable for the street but some would consider it on the edge.
I don't think it goes any lower than "weenie" for Mike. :D
 
#15 ·
The other thing to consider in how people categorize mild to radical: comparison.
If my cam is bigger than your cam, yours is mild.
If my cam is smaller than your cam, yours is radical.
 
#18 ·
A 10 second car has a big cam,
11 second car has a good cam
, 12 second car,your mom can drive it.
What about a car that is running 10's with a turbo? :confused:

From what I understand their cams aren't much bigger than the one that went in the 402.
 
#23 · (Edited)
A lot of it has much to do with the displacement size of the engine that the camshaft in question is going to be installed in. The camshaft you've mentioned, is an average hi-performance cam for a car that's equipped with a 454 CID engine which is street driven often (every week) in the warm weather. But a cam with a dur@.050 of 220 degrees is very mild and "wimpy" :yes: in a 454 or larger engine by street high performance standards. Meaning it isn't a cam designed with high performance and quick acceleration as priority one, whether it's designed by a cam expert like Harold Brookshire or by anyone else. Harold designs mild "wimpy" cams in addition to his best performing racing cams. A cam designer designs all types of cams, and not just the ultimate power producing ones. Some cams are designed for the ultimate valvetrain reliability, longevity, and gas economy too, even by the same guys who design the ultimate racing cams.

Back to my main point (engine displacement).... put that same camshaft you've mentioned in a 632 CID engine, and it's a wimp, (or even in 540 engine it would be wimpy for that matter) because the larger engine displacement requires a camshaft with more lift and duration than a typical 454 CID engine will. Just in the very same way a 632 CID engine requires cylinder heads with larger diameter valves, and especially larger intake and exhaust runner volumes than a typical 350 cid or even 454 cid engine does, given the same RPM goals.

The main thing to remember is that the more power you want from a camshaft, the greater lift and dur@.050 you will have to use (generally speaking) but with more power from a camshaft, you have to also live with, and accept the fact that it will also move that available power further up in the RPM scale. Now on the topic of RPM, a cam of a given size in a 350 CID engine which would bring the horsepower peak to 6,000 RPM for instance, would produce more power in a 400 cid engine, but would produce it's peak power at a lower RPM than it would in a 350 CID engine. So you see, the engine size (displacement) means a lot when choosing camshaft size (specs). Just as your choice of header primary tube diameter is dictated, or should be dictated by primarily engine displacement, and secondarily by desired engine RPM.

All three choices (camshaft specs, cylinder head intake and exhaust runner volume size, & header primary tube diameter size) need to be made with the engine displacement as the primary determining factor, and with the desired engine RPM and intended vehicle use also in mind. All three aspects of the vehicle build combination need to compliment each other and be well matched. Otherwise, you end up with a bad mismatch of parts that work against eachother instead of with eachother, resulting in poor performance, and in the case of severe mistmatches, both poor gas mileage as well as poor performance.

With high performance street driven cars, compromises must be made due to the chosen intended vehicle useage. For instance, radical camshafts will need a greater degree of static compression ratio built into the engine combination, otherwise the engine will run like an old tired dog, and have a lack of throttle response. The really big cams need high static compression ratios that create a need for the use of race gas. But unless you're literally a millionaire, chances are that you wouldn't be able to afford spending $10-$12 per gallon for race gas just to drive your hi-perf car on the street, unless perhaps you're only going to drive it about 10 miles per month or less. But that isn't my idea of a street driven car. So a compromise has to be made just for that reason alone (although there are other reasons as well such as the need for somewhat decent street manners while driving in heavy/slow-moving traffic).

But here's another hypothetical example of the engine displacement thing as to how it relates to camshaft choices: My pump gas, 632 cid engine will run for 30 minutes straight at a 850 RPM idle if I allow it to, and without me even touching the throttle once, and without stalling out nor stumbling. I can walk away from the car and allow it to sit there at an 850 RPM idle, and it will. And that's with a camshaft with .708" lift at the valves, a 110 LSA, and a 270 dur@.050 (well, 268/271 Dur@.050 int./exh. to be exact). With this cam it also has a torque peak at only 4,000 RPM, and a horsepower peak at only 5,900 RPM. But if you install that same camshaft in in a 454 CID engine, not only wil that torque peak and HP peak be about 1,000 RPM higher, but chances are, that it will not idle for long periods of time at 850 RPM without having to blip the throttle periodically to keep it running.

At the same time, take a camshaft like you've asked about with a dur@.050 in the 240 degree neighborhood. Like I said, that would be a nice high performance cam for the typical street driven car with a pump gas 454 cid engine. It would offer a nice compromise of power/acceleration (with the right rear gears and stall speed RPM choice ofcourse), as well as valvetrain longevity and reliability, and with halfway decent street manners too. But install that same camshaft with that same 240 degree dur@.050 spec into my 632 CID pump gas engine, and it will be a wimp. that huge engine displacement will suck up that duration@.050 and will be severely compromised by both the duration as well as the lift it offers. The idle would smooth out to likely having no rumble nor high perf sounding chop at all, and the power peak would occur really much lower than most any hi-perf car enthusaist would want (horsepower probably would peak at only 4,500-4,800 RPM depending on the cylinder heads used, and there would be no power production left above 5,000 RPM at all). This ofcourse is an extreme exampe I've used to clearly illustrate this engine displacement issue in an obvious manner.

The reason I bring up that last example is merely to demonstrate that such things need to be kept in mind if the vehicle in question will have an intended use of street driving where heavy traffic situations can sometimes occur. A camshaft that is too radical will not make for an enjoyable driving experience on the street for any longer than the first 10 minutes. After that, it will get old quick. So these are the types of things that determine a cam as being 'wimpy", "radical" or someplace inbetween the two. Exactly where inbetween those two catagories the cam is which you will choose, needs to be determined by the end user (you) with your intended vehicle use uppermost in your mind. ;)

Sorry for this wall of words above. I didn't intend for this post to be so long, but this is one of those topics that often seems to include many misconceptions and false claims being attached to it, and I wanted to be of help to you in avoidence of those misconceptions. :yes:
 
#24 ·
man, thanks Billy, that really brought it all together. i had this same cam grind in a 427 0.030 that spun a rod bearing. so i got it bored 0.060 and put a 454 crank in it. i drive it about 2-3 times a week. but having never been to the track, i can't say what the top end difference between the two are. i do know i'm very happy with the performance/sound/ streetability.
 
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