# Looking for a rough idle choppy cam



## Seol21 (Mar 14, 2011)

I just took apart a 400 i have for my 64 Lemans. I am currently getting it magged and bored out .060 over. It has existing #11 heads i am gonna use for a while until i can save enough to get some decent heads that are already built. I am looking for a cam with the choppiest idle possible but not sure how high the durations should be. 

Crower 60212 
NT/EXH - Dur @ .050” Lift: 239°/247° RR: 1.5/1.5 Gross Lift: .497”/.522” LSA: 108° RPM: 3250 to 6500 Redline: 6500

Is this way to much or can i go bigger? Point me in the right direction pls.

To be honest i have no idea what tha consequences are for having such high lift.


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## Eric Animal (Oct 28, 2007)

Broken valve springs or bent push rods are 2 possibilities.....


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## geeteeohguy (Feb 2, 2008)

......and poor fuel economy, short engine life, loss of low end power and poor drivability are others........


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## 05GTO (Oct 6, 2004)

Eric Animal said:


> Broken valve springs or bent push rods are 2 possibilities.....





geeteeohguy said:


> ......and poor fuel economy, short engine life, loss of low end power and poor drivability are others........


:agree


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## Seol21 (Mar 14, 2011)

So what you guys think. What's the biggest i should go so i can drive it on weekends ? Just want to be able to hear the cam.


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## jetstang (Nov 5, 2008)

Stock motors should be kept to about 5,000 RPMs unless you like spun bearings.


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## geeteeohguy (Feb 2, 2008)

Need to know: transmission type, rear gear ratio, power brakes or not, air conditioning.....and what type of driving. There are cams that sound pretty good but still yield good driving manners. Many "overcammed" "race" engines have been shut down by much "milder" builds in the real world. It's a question of the whole package, not just one part. Hopefully, Mr P Body will chime in with some real world advice.


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## BearGFR (Aug 25, 2008)

geeteeohguy said:


> Need to know: transmission type, rear gear ratio, power brakes or not, air conditioning.....and what type of driving. There are cams that sound pretty good but still yield good driving manners. Many "overcammed" "race" engines have been shut down by much "milder" builds in the real world. It's a question of the whole package, not just one part. Hopefully, Mr P Body will chime in with some real world advice.


:agree If all you want it to do is sound nasty while it's sitting parked, then go as big and ugly as you like. However, if you want to be able to actually -drive- the car and have it perform decently, then that's a whole 'nuther deal. As others have said, you have to consider the whole package: how do you intend to use the car? Is it going to be mostly highway, mostly street, mostly race? What type transmission (and if an automatic, what's the converter stall speed?) What sort of fuel are you going to run and what's available where you live? (and how much are you willing to pay for it?) ... and what's your budget for parts?

Just remember this: what a camshaft does is basicially determine where the motor's "sweet spot" is --- at what rpm does peak volumetric efficiency occur, where the motor's making the most torque. Thats all it does. Moving the torque peak higher in the rpm range takes advantage of the fact that there's a mathematical relationship between torque, rpm, and horsepower. HP = (torque times rpm) / 5252. So, move the torque peak to a higher rpm and you just increased horsepower, even though the amount of twisting force (torque) being produced is the same.

That nasty idle you like so much is a consequence of an engine that's running so inefficiently at idle that it's struggling just to stay running. That's the trade-off for using a cam that has shifted the torque peak higher in the rpm range. The further you are from that rpm, the worse it's going to run.

Those are the generalities. So, if you want to give us some specifics about your car, how you're going to use it, and your budget we'll be happy to take a shot at it. 

Bear


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## Seol21 (Mar 14, 2011)

Cool. Thanks fellas. I have a TH 400, power brakes, power steering. I just want to be able to drive the car around town. No plans on racing or nothing like that but i would like to have the power. So i guess im just looking for a cam with a choppy sound that will still perform decently. This is what i have now that i took out unfortunately i never got a chance to hear the engine running.
Edelbrok 7157
Operating Range	1500-6500 RPM
Duration Advertised	308° Intake/320° Exhaust
Duration @ .050''	231° Intake/240° Exhaust
Lift @ Valve	.470'' Intake/.470'' Exhaust
Lift @ Cam	.313'' Intake/.313'' Exhaust
Lobe Separation Angle	113.5°
Intake Centerline	112°

Maybe i should just keep this?


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## likethat (Oct 5, 2007)

I bet it had a lopey idle.


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## Mr. P-Body (Jan 20, 2011)

The "Edelbrock" cam you list is a Ram Air IV cam. Edelbrock sells "generi-grinds", they don't design or grind cams. 

That cam will definitely give you a nice "lope". It will also "strain" your torque converter and EAT fuel. A 2,400 RPM converter is recommended for this cam. It's also right "on the edge" for stock springs and valves, with 1.5 rockers. 1.65s will "push it over the edge" and springs (minimum) will be required. That being said, it has been the cam we used for many years. Only in the last 10-12 years have cam grinders exceeded the capabilities for a flat-tappet hydraulic. Overall and very GOOD cam, but not well suited for your goals.

As Bear said, we don't install cams for "sound", we install them to change the power band. 

On a 400, those heads will put static compresson above the 10:1 "line". This is not good for 93 octane gas. Steps should be taken to get the ratio "down" to under 9.5:1.

FWIW

Jim


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## jetstang (Nov 5, 2008)

I put a bigger cam in my 350 just for the sound, because I know the 350 isn't going to outrun anything that is actually quick. I am actually suprised at the performance, although my BBC will smoke it.


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## BearGFR (Aug 25, 2008)

If you want to run pump gas (and I'm assuming you can get 93 octane where you live) then take heed to what Mr. PBody said about compression. That's likely to be a problem for you. 

There's a reason you couldn't get air conditioning in 69 on a Ram Air IV car: the rpm range was too high to be considerd safe for the compressor and the motor didn't make enough vacuum to operate the system and power brakes at the same time. Keep that in mind when selecting a cam shaft, the nastier it is, the less idle vacuum it's going to make. There's a point where you can kiss your vacuum operated accessories (like power brakes and a/c) good bye ---- or at least do what I've had to do on my car: convert the power brakes to a hydroboost system, and put in an aftermarket a/c unit that doesn't need vacuum to operate. As you can guess, neither one is exactly what I'd call "cheap".

Also, if my foggy memory serves correctly, checking that Ram Air IV box on the order sheet in 69 also forced you into one of two rear gear ratios, 3.90 or 4.11. That much gear was needed to allow the motor to get up into its power band quickly. Put that nasty Ram Air IV into an otherwise regular GTO with even 3.23 gears, and a "plain old" D-port GTO would eat it alive.

Starting to get the picture? It's possible to get the results you're looking for, but the key is to "engineer" the whole car from bumper to bumper so that everything works together.

Bear


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## 85_SS (Jul 26, 2010)

If you're curious what it would sound like, here's my car with a RAIV cam:






Unfortunately it has a 3.36:1 gear ratio - helps out with mileage and cruising RPM of course, but it doesn't seem to have much low end because of it. Not sure if I'll ever bother changing the gearing (especially with current gas prices).

I'll also use the car strictly for cruising and love the sound of a bigger cam. Compared to the mild 350 in the Monte, it is a bit tempermental at times (but worth it as I also love a lumpy idle).


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## likethat (Oct 5, 2007)

That is an 8 track of the car running isn't it and not there real car


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## 68greengoat (Sep 15, 2005)

Sounds awesome, 85 SS. What are you running for the exhaust?


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## 85_SS (Jul 26, 2010)

LOL, well there is a "Led Zeppelin* IV*" 8-track in the player - close enough to a RA*IV* cam right? 



68greengoat said:


> Sounds awesome, 85 SS. What are you running for the exhaust?


Thanks  ...it's a basic stockish true dual setup with RA exhaust manifolds and flowmaster mufflers:
http://carphotos.cardomain.com/ride_images/4/601/389/39000194060_large.jpg
...not sure what model - I'll have to look up the part number next time I'm under it.


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## Seol21 (Mar 14, 2011)

Cool. Thanks for all the help guys. I decided to keep the cam and just look for better heads and go from there. I am just gonna do it right.
85 SS your car sounds killer. Thats what im shooting for.


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## 85_SS (Jul 26, 2010)

Glad to help  For reference, the heads on my motor are #12 RAIII heads.


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