Posted By: Verga
Idle is better with exhaust corked - 06/06/08 02:57 AM
If you get a better idle quality with the exhaust corked, vs. open, does that mean that open exhaust richens the mixture?
Just wondering.
Just wondering.
Idle is better with exhaust corked
Posted By: BobR
Re: Idle is better with exhaust corked - 06/06/08 03:05 AM
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
Posted By: Verga
Re: Idle is better with exhaust corked - 06/06/08 12:53 PM
Quote:Quote:
If you get a better idle quality
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
I have always heard that open exhaust leans your mixure also. The cars idles much smoother with the exhaust corked, especially in gear.
Posted By: Anonymous
Re: Idle is better with exhaust corked - 06/06/08 01:00 PM
i think the answer is obvious.. don't you? in case you don't..
open exhaust requires a different tune then a closed exhaust.
open exhaust requires a different tune then a closed exhaust.
Posted By: dmerc
Re: Idle is better with exhaust corked - 06/06/08 01:02 PM
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.
Posted By: AdamR
Re: Idle is better with exhaust corked - 06/06/08 01:37 PM
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.
Posted By: Verga
Re: Idle is better with exhaust corked - 06/07/08 02:51 PM
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!!!
Posted By: Verga
Re: Idle is better with exhaust corked - 06/07/08 02:53 PM
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.
Posted By: BobR
Re: Idle is better with exhaust corked - 06/07/08 04:01 PM
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
Posted By: Verga
Re: Idle is better with exhaust corked - 06/07/08 04:05 PM
[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.
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.
Posted By: mark7171
Re: Idle is better with exhaust corked - 06/07/08 06:03 PM
yes the books will say drilling is an option.
you really shouldnt half to unless this is some monster of a brute.
you really shouldnt half to unless this is some monster of a brute.
Posted By: 340727dart
Re: Idle is better with exhaust corked - 06/07/08 06:17 PM
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 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.
Posted By: VanishPt
Re: Idle is better with exhaust corked - 06/07/08 06:52 PM
open the idle screws an 1/8 turn.
Posted By: BobR
Re: Idle is better with exhaust corked - 06/07/08 07:32 PM
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
Posted By: Anonymous
Re: Idle is better with exhaust corked - 06/07/08 07:44 PM
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!!!
