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cam that will idle like no other but is no slouch on the low end, any suggestions?

18K views 17 replies 14 participants last post by  fiscus  
#1 ·
I want a cam that idles like crazy, but still has low end torque and has a 5500 or so RPM limit. My engines a chevy 350 and I plan to use a 2400-2600 stall converter with 3.73 cogs. Should I look for a cam with a shorter intake duration with a long exhuast? any suggestions? Thanks
 
#2 ·
I'd suggest you re-think your cam requirements. A cam that 'idles like crazy' isn't going to be responsive on the low end and isn't going to be very friendly with your converter. Something in the 220° @ .050" lift range will be pretty much all in by 5500, will work well with a 2400 stall converter and will have good off-idle response.
 
#3 ·
You are talking opposites. Overlap will give you the crazy idle, but short duration (and the limited overlap associated with it) will give you low end torque.

If you're hell-bent on it, you'll have to do a completely custom cam. Here's what you need: You need mild duration. I agree with onovakind67; no more than 220 @ 50 duration on the intake. To get a slightly lumpy idle you could have a custom cam ground on a 107 LSA for use with roller lifters and a fast exhaust ramp, but you'll be giving up idle vacuum, power brakes, need to completely recurve the idle and primary fuel curves and the entire ignition curve.

Basically what you're asking is for the least possible street drivability, weak power, and losing the ability to run any vacuum-driven accessories like emissions equipment, EFI, power brakes, or A/C and climate control.

You'll end up with all the bad parts of a hot engine, but none of the heat... just to attain a lumpy idle.
 
#6 · (Edited)
Get a cam with about 70-75 deg's of overlap, That's a lot for a driver, but you can make it torqey. Get one on a 106-108 LSA,with as much lift as possible, then get heads from a 305 or fuelie heads with the small valves, and chambers, get bigger exh valves if possible. A little bowl blend and short side radius work for velocity. keep compression up around 10.5, get a dual plane intake, with either a q-jet or an anular holley, and a free flowing exhaust. Any catylitic's or exh. manifolds will kill you.

She won't be a monster up top, but she'll have a lopey idle, and pull from 15-1800
An overdrive and steeper gears would help. should be able to get a 850rpm idle.

Also, If you don't mind adjusting the valves twice a year, get a solid cam. Hydraulics tend to bleed down at idle reducing the actual duration, and taking away that nice brap-bu-bu-brap-bu-bu

Later
Steve
 
#8 ·
The best off the shelf cam for what you want is a Crane Energizer 274H06.

Pn. 10017

274 degrees total
218@0.050
0.450" lift
106 LSA

Make sure your compression is at least 9.5-1, and I don't mean the number on the piston box either, measure everything to be absolutely sure. If you don't, those 10-1flat-tops will probably have you at 8-1 and the engine will be an absolute dog.

Larry
 
#9 ·
Warrant said:
I want a cam that idles like crazy, but still has low end torque and has a 5500 or so RPM limit. My engines a chevy 350 and I plan to use a 2400-2600 stall converter with 3.73 cogs.
Everyone has their opinions, but I am going to make this statement based on personal experience, not a technical explanation.

If you have some decent heads, I think the Performer RPM cam will deliver what you want. It has a fairly lumpy idle, and in my engine had great throttle response and good mid-range. It pulls just as advertised (up to 6500). My setup was a 355, 9.5-1, Edelbrock RPM heads, 650 DP carb, HEI, 1 5/8 headers, 2 1/2" duals, 2800 stall, 4.10 gear with 28" tall tires. I did not need a vacuum cannister for the brakes to work, but I did add a cheap Summit can for safety.

What heads are you running?

Ed www.edgesz28.com
 
#10 ·
coldknock said:
The best off the shelf cam for what you want is a Crane Energizer 274H06.

Pn. 10017

274 degrees total
218@0.050
0.450" lift
106 LSA

Make sure your compression is at least 9.5-1, and I don't mean the number on the piston box either, measure everything to be absolutely sure. If you don't, those 10-1flat-tops will probably have you at 8-1 and the engine will be an absolute dog.

Larry
I concur here. This is the Crane's "3/4 Cam" and is designed specifically to give that rumpety sound and still maintain a level of driveability.
 
#17 · (Edited)
Sound

I am not a engine guru. But here is what I am running and how it sounds. Not the biggest lope, but it will give you an idea of a streetable 350 that runs 11's

Comp Roller Cam 245 duration @50 .600 lift intake and exhaust.
3200 Stall bolted to a custom built 700R
4.56 rear gears
Old School Camel Humpers 2.02's with a little magic dust.
Torker II Intake
Mighty Demon 750
Intial timing at 20 degrees, with total of 36

Chevy Small Block 355 . Best run of 11.488 1/4 @ 120.08 mph .

And I run power brakes with no vacuum issues.

Sounds like this CLICK HERE My x pipe in the exhaust really smooths out the exhaust at idle and is much more lopey with x pipe removed.

I have engine components people on this forum said will never produce power, and would be a dog on the bottom end. My 1/4 mile time say other wise for a 4100 lb car and a small block.

Happy Holidays....... :thumbup: