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Idle is better with exhaust corked
#68291
06/05/08 10:57 PM
06/05/08 10:57 PM
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Joined: Oct 2006
Posts: 302
Middle of the US
Verga
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If you get a better idle quality with the exhaust corked, vs. open, does that mean that open exhaust richens the mixture?  Just wondering.
"Im supercharged, might explode in your face"
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Re: Idle is better with exhaust corked
[Re: Verga]
#68292
06/05/08 11:05 PM
06/05/08 11:05 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
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Quote:
If you get a better idle quality with the exhaust corked, vs. open, does that mean that open exhaust richens the mixture?
Just wondering.
If anything the open exhaust leans your fuel/air mixture. How do you define better? Are you sure it isn't just because you have more unwanted sound? -Bob
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Re: Idle is better with exhaust corked
[Re: Verga]
#68294
06/06/08 09:00 AM
06/06/08 09:00 AM
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Anonymous
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Anonymous
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i think the answer is obvious.. don't you? in case you don't..
open exhaust requires a different tune then a closed exhaust.
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Re: Idle is better with exhaust corked
[Re: dmerc]
#68296
06/06/08 09:37 AM
06/06/08 09:37 AM
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Joined: Jan 2003
Posts: 7,978
Bethel Ct
AdamR
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Quote:
I read somewhere that high exhaust backpressures actually lean out the mixture because at idle when there is valve overlap some of the exhaust backs up into the cylinder and dilutes the incoming mixture. So in theory open headers will make the engine run richer at idle.
You have it backwards. The exhaust back pressure would richen the mixture.
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Re: Idle is better with exhaust corked
[Re: Verga]
#68298
06/07/08 10:53 AM
06/07/08 10:53 AM
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Joined: Oct 2006
Posts: 302
Middle of the US
Verga
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It seemed odd to me that the idle was better corked than open, cuz I still dont have the carb dialed in 100 percent at idle. Ive got to start opening the holes in the blades, cuz too much of the transer slots are showing already. I figured with the exhaust open it would raise the idle RPM slightly, but it did the opposite.
"Im supercharged, might explode in your face"
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Re: Idle is better with exhaust corked
[Re: Verga]
#68299
06/07/08 12:01 PM
06/07/08 12:01 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
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Quote:
It seemed odd to me that the idle was better corked than open, cuz I still dont have the carb dialed in 100 percent at idle. Ive got to start opening the holes in the blades, cuz too much of the transer slots are showing already. I figured with the exhaust open it would raise the idle RPM slightly, but it did the opposite.
If you have to open the blades past the transfer slots then you are dead rich and the open headers are bandaiding the problem. I have always remedied that situation by drilling holes in the blades. Start small-say a 3/32 drill and open as needed. Drill all 4 blades and chamfer the holes. Other methods include leaning the idle bleeds ect but the drill method has always worked for me. BTW this is exactly what the Holley book will tell you to do. -Bob
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Re: Idle is better with exhaust corked
[Re: BobR]
#68300
06/07/08 12:05 PM
06/07/08 12:05 PM
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Joined: Oct 2006
Posts: 302
Middle of the US
Verga
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[quote
If you have to open the blades past the transfer slots then you are dead rich and the open headers are bandaiding the problem. I have always remedied that situation by drilling holes in the blades. Start small-say a 3/32 drill and open as needed. Drill all 4 blades and chamfer the holes. Other methods include leaning the idle bleeds ect but the drill method has always worked for me. BTW this is exactly what the Holley book will tell you to do. -Bob
Yes, I agree Bob, but it idles better corked, not open. Which to me is backwards. If uncorked leans it out, Id think it would idle better open.
"Im supercharged, might explode in your face"
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Re: Idle is better with exhaust corked
[Re: Verga]
#68302
06/07/08 02:17 PM
06/07/08 02:17 PM
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Joined: Jan 2003
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Arkansas
340727dart
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Uncorking headers leans out the mixture due to a non-restricted flow.
Your engine is able to move more air uncorked. You need to fatten up the mixture to compensate for the increased air flow.
Reading your spark plugs corked vs. uncorked will tell you that.
Your life is not my fault.
My life is none of your business.
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Re: Idle is better with exhaust corked
[Re: VanishPt]
#68304
06/07/08 03:32 PM
06/07/08 03:32 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
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Quote:
open the idle screws an 1/8 turn.
If he is truly into the transfer slots the idle mixture screws won't do much, in anything. I agree with pulling and reading your plugs. Idling with the transfer circuit will give you dark and maybe wet plugs. -Bob
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Re: Idle is better with exhaust corked
[Re: Verga]
#68305
06/07/08 03:44 PM
06/07/08 03:44 PM
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Anonymous
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Anonymous
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Quote:
Quote:
i think the answer is obvious.. don't you? in case you don't..
open exhaust requires a different tune then a closed exhaust.
I think its obvious you are an A!!H!le. Dont you? in case you dont, you are one!!!
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