what makes a mild cam not a mild?? [Archive] - Chevelle Tech

: what makes a mild cam not a mild??


atle
Jan 27th, 11, 2:26 PM
: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

69-CHVL
Jan 27th, 11, 2:42 PM
Perception :D

dreis454
Jan 27th, 11, 3:06 PM
: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


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.

bracketchev1221
Jan 27th, 11, 3:11 PM
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.

Yellomalibu
Jan 27th, 11, 3:19 PM
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.

atle
Jan 27th, 11, 3:35 PM
thanks guys, it sounds pretty aggressive at idle and idles at 900 very nicely. i've heard some very wicked cars with smaller cam specs than mine, so just curious.

Two Lane
Jan 27th, 11, 3:58 PM
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


Once upon a time, cams came as stock, street, 3/4 race,and full race, meaning:

---no improvement over stock,

---better but not killer,

---hot street stick,

---and overkill.


HTH :)

Yellomalibu
Jan 27th, 11, 5:58 PM
Once upon a time, cams came as stock, street, 3/4 race,and full race, meaning:

---no improvement over stock,

---better but not killer,

---hot street stick,

---and overkill.


HTH :)

Nice.

I'm guessing the "RV cam" is in the same category as the "street" cams, right? :yes:

SWHEATON
Jan 27th, 11, 10:26 PM
thanks guys, it sounds pretty aggressive at idle and idles at 900 very nicely. i've heard some very wicked cars with smaller cam specs than mine, so just curious.
====================

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

atle
Jan 27th, 11, 10:50 PM
thanks guys, much clearer to me now.

Xtreme70SS396
Jan 28th, 11, 8:56 AM
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

70-SS454
Jan 28th, 11, 4:22 PM
more lift & duration....

Two Lane
Jan 28th, 11, 5:17 PM
Nice.

I'm guessing the "RV cam" is in the same category as the "street" cams, right?





Yup! :)

mr 4 speed
Jan 28th, 11, 5:50 PM
I had a "fellow" member here call a mild 223/231 @.050 cam by Harold "wimpy" :D
Wimpy in my mind is the 396 L35 or L48 350 cam (about 198-204@.050)

Yellomalibu
Jan 28th, 11, 9:51 PM
I had a "fellow" member here call a mild 223/231 @.050 cam by Harold "wimpy" :D
Wimpy in my mind is the 396 L35 or L48 350 cam (about 198-204@.050)

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.

SMALLBLOC
Jan 28th, 11, 10:04 PM
A 10 second car has a big cam,
11 second car has a good cam
, 12 second car,your mom can drive it.

MEJ1990TM
Jan 28th, 11, 11:14 PM
I had a "fellow" member here call a mild 223/231 @.050 cam by Harold "wimpy" :D
Wimpy in my mind is the 396 L35 or L48 350 cam (about 198-204@.050)

Yeah, that is pretty small.

I think the cam that went in the 402 is pretty mild. It's got a nice lope at an idle, but it still works with the power brakes. It's 244 @ .050.

MEJ1990TM
Jan 28th, 11, 11:18 PM
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.

Stokerboats
Jan 28th, 11, 11:40 PM
Gas Prices make a Big Cam a Big Cam as well as the frown on the guys face in your rear view mirror.

MrToadsWildRide
Jan 28th, 11, 11:41 PM
====================

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

This is the truth, and simply put. Sound wise that is.

MrBill66Malibu
Jan 29th, 11, 9:00 AM
It just sounds like cam envy to me!!! LOL :)

SWHEATON
Jan 29th, 11, 11:51 AM
I had a "fellow" member here call a mild 223/231 @.050 cam by Harold "wimpy" :D
Wimpy in my mind is the 396 L35 or L48 350 cam (about 198-204@.050)

=====================

2X THAT !!

WITH ONLY .398 GROSS LIFT FOR THE L35 396/325HP,YIKES/LOL!!!!!!

When i went from that 198/198,.398/.398 cam in my 396 to the old crane single patt 228/228,.544/.544,112 lsa along with extrude honed ex manifolds/2.5" ex pipes front to back with flowmasters,tweaked q-jet,and beefed up stock ign a bit along with recurving the dist to run approx 18-20 deg base and 18 deg mech all in by 2500-2600rpm for 36-38 total & it ran a heck of a lot stronger compaired to with the stock cam.

The car then had respectable performance with 3.31's & 4spd still being very streetable with pelnty of vacvuum for pwr brks either.

I rblt the motor a few yrs back and it now has slightly less cam (mistake) at 222/226,.525/.525,112 deg lsa with everything else being the same prior to rbld but now the lrg port 063 heads have mild pocket porting along with manley undercut swirl polished race flow valves & .030 speedpro forged slugs for approx 9.8 comp + - due to slight decking of block/heads.

But it runs run's slightly stronger with the smaller cam then it did with the older slightly hotter crane cam poss due to headwork/fresh rbld/ etc.

But the crane cam had a nicer/hotter sounding slightly choppy idle when the motor was warmed up that i do miss.

I est its got approx 370-380hp/430-440lbs trq which is more then enough @ 55yrs YOUNG (LOL!!) to have some fun with once in a while with the 3.31 gear & pulling gears it's m20 .

SCOTT

BillyGman
Jan 30th, 11, 6:07 AM
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:

atle
Jan 30th, 11, 8:25 AM
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.

mr 4 speed
Jan 30th, 11, 9:16 AM
Anhtuan...nice 70 :thumbsup: I think I remember this car..does it have Merlin heads on it?

atle
Jan 30th, 11, 9:23 AM
Thanks! It actually has GM iron 291 rectangular heads. heavy son of a guns. :D