Idle sound

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1973dusterkid

1973dusterkid

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Ok so me and a buddy where at the dragstrip just watching and hanging out, he brought up a good question. My Duster idles pretty good hits super hard and lopes good but its a slow lope and most all the fast cars on the track have a very fast idle but hit super hard so my question is what specs in a cam make the difference between a slow choppy idle and a fast choppy idle.
 
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You might want to edit your post so it makes sense, please

But if I understand it right;
idle-lope is a by-product of cam timing. The bigger the cam the worse the lope, and eventually the idle has to go up so the engine will keep on running.
Lope is not something to be desired for a streeter, cuz the side effect in a streeter is a soft bottom end, requiring big TCs and big gears to overcome.
Some cam manufacturers are building cams to fit this niche, of guys wanting big cam sound, but it has another side-effect; loss of efficiency.There are lotsa thumper-cam audio clips on the tube. The truth is these cams have some of the slowest ramps out there, and I certainly wouldn't rush out and buy one. Streeters are limited to burning pumpgas, which means they are compression limited. To make power they need the fastest ramps to be found. You have to get the valves open as fast as possible to get the heads flowing, hold 'em open as long as possible,to pull in as big a charge as possible, and then slam the door shut before the piston has a chance to push the charge back into the intake.The charge needs to be in the chamber, not messing up the idle. The better the cam is at doing this, the nicer will be the power curve. This type of cam is also known as a high-intensity cam cuz the speed of the lobes is intense.Intensely fast.They may have only small amounts of lope. A street-cam like that will often make pretty good mpgs too. And that is a triple whammy for street; hi-torque, hi-power, and reasonable fuel mileage.
 
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1973dusterkid said:
Ok so me and a buddy where at the dragstrip just watching and hanging out, he brought up a good question. My Duster idles pretty good hits super hard and lopes good but its a slow lope and most all the fast cars on the track have a very fast idle but hit super hard so my question is what specs in a cam make the difference between a slow choppy idle and a fast choppy idle.
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It may have less to do with the cam and more about the tune up settings. I have a bracket car that idles high. I have my distributor locked at 34 degrees and idle set at 1300 . if I was to back my initial timing out and lower my idle I would get a nasty lope.
 
wow, thats a fast car. You see the nuts on the street doing burn outs and the ricers spooling up after 100 feet but that takes the cake. It hooks......
Oh yeah, I heard a El Camino just the other day. His idle was like 400 RPM and the Flowmasters were pinging like bells..dink..dink.DINK..dink...dink.DINK. Like a huge Harley. People were like asking "WTH is wrong with your car?" I dont think that was what he was looking for.
 
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I think compression, duration and a tight LSA contribute to that sweet pissed off sound lol

Almost forgot the idle screw..thanks Rusty
 
You can have a lopey idle but not maximum performance. Like AJ mentioned there's lots of Thumper cam's out there. Most have a notable idle but smooth out at about 2000 rpm with not a lot extra after that. But. If this is what you want here's a good example with a Hughes Whiplash cam. Got to love the sound. Ya it's a 318!
 
toolmanmike said:
You can have a lopey idle but not maximum performance. Like AJ mentioned there's lots of Thumper cam's out there. Most have a notable idle but smooth out at about 2000 rpm with not a lot extra after that. But. If this is what you want here's a good example with a Hughes Whiplash cam. Got to love the sound. Ya it's a 318!
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RustyRatRod said:
The idle screw.
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^^^^ This. At 1:32 you can see the idle is set at about 500rpm add that to a tight centerline and you'll have that sound.

Same car with open headers. It smooth's right out as soon as the rpm come up.

 
Idle screw.

My 340 has a XE274H. At 600 RPM it has that lazy lopey "muscle car" idle. At 1000 RPM it has that fast racey idle. I keep it at 1000. Better vacuum. Better throttle response. Puts you in the seat and burns the tires every time. I couldn't care less about sound. A car that sounds cool but is slow as hell isn't cool.
 
That Duster does sound really nice though. Seems to run real good to
 
I met the guy last year at the Nats. He had put a 360 in sometime in late 2014
 
I've been disappointed by the almost no-lope idle of every cam I have installed in my 10.8 to 11.3 engine. But every cam was a fast-rate. And the 276/286/110 in it now is no exception. But it goes 93 in the 1/8th, and that is no disappointment at all.This cam doesn't lope until the idle is down to under 600, with the idle-timing backed off from 14* to 7*, which I do from the drivers seat,electronically, with a dial-back timing device.
The 292/292/108cam had the most lope.That cam had the latest closing intake, at 66*,70*,74*and 78*,(yup I tried that cam all over the place),vs 64* of the current cam.That 292 was just too big for my definition of street.
 
It's both!
If it's too lumpy to idle at 650, as in it want's to stall, then you have to crank it up. maybe it will stay running at 700, maybe not. Keep cranking it up til it stays running. Along the way the T-port sync will get screwed up so then the idle-speed will have to be re-adjusted with idle-air bypass and idle timing. Then the idle will smooth out, so maybe now you can slow it down some. But there is a point when it becomes too slow again; maybe you got no oil-pressure at 500rpm, or maybe the cam drops a lobe or two or three,idling down there with insufficient oil-splash and massive spring pressures.. Too slow is not the way to make a lumpy sound.Besides everybody will know what game you are playing. I watch out for guys who have too smooth an idle but it might be 800. See they could be hiding their cam.....and know a bit about tuning. And if they are sharp that way, maybe they are sharp in other ways too. I might not want to find out!
But if they are idling at over 1000 and lumpy, They are waaaay over my league.I am just going to tippy-toe on by.....Don't pay me no-never-mind, I'm just sliding on thru...Look the other way....Where are my cheap sunglasses?
 
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AJ/FormS said:
It's both!
If it's too lumpy to idle at 650, as in it want's to stall, then you have to crank it up. maybe it will stay running at 700, maybe not. Keep cranking it up til it stays running. Along the way the T-port sync will get screwed up so then the idle-speed will have to be re-adjusted with idle-air bypass and idle timing. Then the idle will smooth out, so maybe now you can slow it down some. But there is a point when it becomes too slow again; maybe you got no oil-pressure at 500rpm, or maybe the cam drops a lobe or two or three,idling down there with insufficient oil-splash and massive spring pressures.. Too slow is not the way to make a lumpy sound.Besides everybody will know what game you are playing. I watch out for guys who have too smooth an idle but it might be 800. See they could be hiding their cam.....and know a bit about tuning. And if they are sharp that way, maybe they are sharp in other ways too. I might not want to find out!
But if they are idling at over 1000 and lumpy, They are waaaay over my league.I am just going to tippy-toe on by.....Don't pay me no-never-mind, I'm just sliding on thru...Look the other way....Where are my cheap sunglasses?
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Very True and Funny!
 
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