Your looking for valve overlap. Look for a high dur / low LSA. I would say the lope might start at 220+ degree dur and 110- LSA. But that would be a little lope. If you want to shake your teeth out keep it around 108 or less on a high lift cam. Is it going to be in a race car or a daily driver?

 

its goin in a daily driver for the moment but within a year it'll be a street maching its a 388 stroker smallblock chevy, i have a comp cams 280H in it right now but i dont like it no low end and it doesnt lope liek i want it too, main power is only after 3500 rpm.....which i might add is a ****load of power but its too high for me access where idrive i want low end but i want power all the way to 6400 rpm 6000 minimum and a lopey idle

 

You want both worlds, low end power and a rough idle. But, one excludes the other. You seem determined to have that rough idle which means, as stated, you need high duration which drives the power curve up.

 

You might be able to do a custom ground cam, keep the duration low (like 220/225), but narrow the LSA to 106 or 104 to create the overlap and then install it 4 deg. adv. to pick up a little more bottom end. If you have a PC dyno program you could try it and see.

 

lope

Isky's mega-cam 270 adv duration (221 at .050) and 108 lobe center. Just my 1 cent.

 

Crane 3/4 cams...........Energizer 3/4 Race Hydraulic Flat Tappet Camshaft & Lifter Kit
Lift: .470''/.470''
Duration: 282°/282°
RPM Range: 2400-6200
ROUGH IDLE, MODERATE PERFORMANCE USAGE, GOOD MID-RANGE TO UPPER RPM HP, 3000-3400 CRUISE RPM, 9.5 TO 11.0 COMPRESSION RATIO ADVISED.

Grind Number: 282 H06
Operating Range: 2400-6200 RPM
Duration Advertised: 282° Intake / 282° Exhaust
Duration @ .050'' Lift: 226° Intake / 226° Exhaust
Valve Lift w/1.5 Rockers: .470'' Intake / .470'' Exhaust
Lobe Separation Angle: 106°
Max Lift Angle: 101° ATDC Intake / 111° BTDC Exhaust
Open/Close @.050'' Cam Lift: Intake - 12° BTDC (opens) / 34° ABDC (closes)
Exhaust - 44° BBDC (opens) / 2° ATDC (closes)

I have this cam in a 355 and it sounds quite healthy, but has more low end power than you would think.......

 

Comp XE 262, 268 good low rpm power with nice lope and good driveability. I will never understand why people want to sacrifice low end torque on a street motor for a lopey idle. Tune your exhaust instead if you must have a lopey idle. Stand next to a new Vette and tell me you don't like the exhaust sound but it idles smooth as a baby's butt!

 

In my experience, especially with big displacement motors, a variable pump lifter, Rhoads specifically, can give you the best of both worlds, a rumpity-rump idle with major power when you make it spin.

 

Roller anyone?

 

This "lopey" business is driving me Loopey....................pick a cam for how it performs, not what it sounds like. Jeeeeeeeeeeeessssus-H-Key-rist..........

 

^^^ +1 !!

Look through Comp's custom lobe catalog. Choose a duration and LSA for you target use of the vehicle, period. If you want it to be a touch lopey sounding, use a roller with a really fast exhaust opening ramp and then use good quality headers. The fast ramps will put a more forceful exhaust pulse in the exhaust giving it a slight tick-it sound. Not the lopey idle you want, but a nice sound anyway. I learned this from a Lunati grinder who is retired. He hangs around some of the Oldsmobile forums you might be able to find him for more tech on it.

If you choose a cam for how it sounds, you are almost guaranteed to be disappointed in its performance.

 

Comp just came out with this line of cams they call the thumper.It sounds like what your looking for.
http://www.compcams.com/thumpr/
You could also ask lazer cams
http://www.Lazercams.com
I would go with a custom grind.Something similiar to a 274XE but with a 106lsa and 104intake centerline

 

True, but those thumpers START at 283 advertised, 227 degrees @50. That is strictly 2500-stall and light car territory in my book. He said he currently has a 280 advertised cam and that's too much for him.

If you could maybe get them to do a 212/222 on that same 107 LSA you might retain some lope but bring your torque peak out of the rafters.

 

I haven't ran it yet, but I'm using a Lunati VooDoo 262 cam with 1.6 rockers and a 105 LSA in my 388 in hopes of exatly what you are searching for. I'm running it in a 87 TA with stock tire height so low end isn't a huge ordeal, but I want a streetable cam with a nice sound. I've ran bigger rand smaller camms and they all have their place, but I think this time around this cam will be perfect. Also according to DesktopDyno (which is really just a good SWAG) my peak torque should be around 3500 with peak hp at about 5500. 475/450. With a good dual plane, headders, a good carb, good heads, roller rockers and gapless rings I say that should be pretty possible.

 

what numbers in the specs of a cam will tell you if it has a lopey idle or not and if so how much?

Talk to the guys at lazercams.com they will help you out.
DoC

 

Correct me if I'm wrong but I believe engine size will have an effect on how a cam sounds would it not? I don't know where I got this or even if it's right but somewhere along the line I've come across this. Would a Comp 280H sound rougher in a 283 than in a 400? Also, I know big cams tend to have more of an effect on vacuum on smaller engines than on the bigger ones.

 

Poncho, you must be old school like me. Nothing makes my hair stand on end than somebody saying they are shopping a cam by how it sounds rather than how it performs.

 

Poncho, you must be old school like me. Nothing makes my hair stand on end than somebody saying they are shopping a cam by how it sounds rather than how it performs.

No, I'm just old.........Cars dont go to school.

 

Much over 65 degrees overlap (at base) will give a rough idle. For every degree of lca you subtract you add 2 degrees of overlap.

 

I use a engle EP-22, ruff idle good bottom end, i ran a edelbrock rv cam for a while smooth idle good bottom end. The engle has as much torque as the edelbrock but you will need a stall of at least 2500, but it will turn up to 6000 no problem, and sound like a 1972 drive-in cam, we used to call them PATIO cams for the patio burger joint in my town. P.S. mine is in a short stroke 327. Wormy.

 

thanks guys i really apriciate your help, and to the ones that told me i was shopping for a cam by the way it idled thats not the truth i am designing a custom grind lunati cam and i wanted to know what numbers to mess with to get a lopey idle......thnx again

 

shopping for a cam makes as much sense as buying paint for the color instead of its ability to prevent rust. If its what some one ois after then there's nothing wrong with that. For me- I like a rough driving car rather than a smooth boring power band- too boring- I also like flat primer. But many people like a near stock idle with a 15,000 dollar paint job.

 

heck yeah!!! as far as im concerned primer is one of the best colors!!!

 

388

I've used that cam in several SB Chevy's and they made good low-end torque. I'd suggest you look at the advance curve in your distributor and modify it as follows:

What kind of distributor are you using? If it's an MSD you need to remove the heavy springs that came installed by MSD. Replace them with one silver and one blue spring. Leave the blue advance shim in it.

With the vacuum advanve disconnected you want the initial timing to be about 15 degrees before TDC at idle and total timing about 37 degrees BTDC and have it reach full advance about 2800-3000 RPM.

The vacuum advance should be limited to about 10-12 degrees advance so you have a total timing of about 45-50 degrees during cruise (high manifold vacuum) conditions.

Ignition timing can make or break the way an engine runs. I recurve lots of distributors and ALWAYS see an improvement...sometimes a very drastic improvement.

If you have questions you can call me at 816-436-6108 evenings.

Ron

 

put a big cam with low gears
i got a (single pattern) Summit 292 cam (234 at .050 .488 inch lift) and I run a stock converter and it does fine even with a posi 3.08 high way gears in the rear and a relative stock TH-350c (shift kit). It peels out but doesnt roast tires but lower gears would help with lower end