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11-19-2009, 07:17 PM
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CC Member
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Join Date: Jul 2005
Location: Bartlett,
Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,448
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Not Ranked
why didn't you just open the idle eze valve for more idle???
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11-19-2009, 07:19 PM
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CC Member
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Join Date: Jul 2008
Location: Driftwood,
TX
Cobra Make, Engine: Contemporary Cobra, 427 side oiler
Posts: 1,850
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Not Ranked
Because even at full open it wasn't enough.
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11-19-2009, 07:46 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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Not Ranked
el
Mine is smooth as silk everywhere, as Tom mentioned, I cruise in the transition area before the mains kick in. It is lean in this area when everything else is OK,this is my problem. I can make it run richer @ cruise but then I sacrafice the other correct adjustments.
I drive with a LM1 so I can see exactly what it is doing. That is why I asked Tom for more info. He seems to have the answer I am looking for.
Thanks for your help
Craig
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11-19-2009, 08:00 PM
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CC Member
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Join Date: Jul 2008
Location: Driftwood,
TX
Cobra Make, Engine: Contemporary Cobra, 427 side oiler
Posts: 1,850
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Not Ranked
Quote:
Originally Posted by cdnus
It is lean in this area when everything else is OK,this is my problem.
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Which carb?
p.s. I edited down my prior post given that it wasn't relevant to your condition. |
11-19-2009, 08:25 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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Not Ranked
el
950HP
Craig
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11-19-2009, 08:26 PM
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CC Member
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Join Date: Sep 2009
Location: Sacramento,
CA
Cobra Make, Engine: ERA 707, 446ci FE
Posts: 1,115
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Not Ranked
I'd love to put an O2 port on my exhaust but I'm not sure what's required. I have coated primaries, so drilling and welding would be not-so-hot. Can I drill and tap a port right on the front of the #5 exhaust port, on the head? I have a nice clear angle there on the front corner but I'd have to look at a bare Performer RPM head to make sure there's nothing but metal in that curve. Would that be a functional place to put an O2 sensor, or do I need one on each side?
__________________
= Si Opus Quadratum vis, angulos praecidere noli. =
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11-19-2009, 08:31 PM
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CC Member
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Join Date: Jul 2005
Location: Bartlett,
Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,448
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Best place is in the collector--either or both sides--where ever tho you have to ensure there are no exhaust leaks that can let in air on reversion showing a lean condition that doesn't exsist.
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11-19-2009, 08:36 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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Gunner
Best location is the collector. I have in both sides.
About 1/3 from bottom so the sensor will clear the body. I have read of many guys installing them after coating by doing a little grinding & touch up with high temp spray.
Craig
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11-19-2009, 08:41 PM
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CC Member
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Join Date: Jul 2008
Location: Driftwood,
TX
Cobra Make, Engine: Contemporary Cobra, 427 side oiler
Posts: 1,850
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My understanding is the idle air bleeds on Holleys and Demons are what you use to correct rich/lean peaks and valleys across the entire fuel curve and assumedly at the point of transition. I am sure Jerry can comment on this.
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11-19-2009, 08:59 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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They do, but they richen or lean the whole range, then when you recalibrate the transition is lean again. I cannot seem to find a happy balance.
I can get the carb close to perfect I think, except this 1 area. It does run lean enough that it causes concern. Only in the area that Tom referred to.
Thanks again
Craig
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11-19-2009, 09:29 PM
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CC Member
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Join Date: Sep 2009
Location: Sacramento,
CA
Cobra Make, Engine: ERA 707, 446ci FE
Posts: 1,115
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Quote:
Originally Posted by cdnus
Gunner
Best location is the collector. I have in both sides.
About 1/3 from bottom so the sensor will clear the body. I have read of many guys installing them after coating by doing a little grinding & touch up with high temp spray.
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Do either you or Jerry have a photo? Is it a standard fitting or something particular to O2 sensors?
__________________
= Si Opus Quadratum vis, angulos praecidere noli. =
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11-19-2009, 09:33 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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They are called o2 "bungs"
Available almost any speed shop. Mild & stainless steel. If you intend to buy a meter they usually come in the kit.
Craig
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11-19-2009, 09:45 PM
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CC Member
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Join Date: Sep 2009
Location: Sacramento,
CA
Cobra Make, Engine: ERA 707, 446ci FE
Posts: 1,115
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Got it. Thanks. I ass/u/me I can drill and weld these to the inside lower curve so they're not generally visible? I further ass/u/me it's useful to be able to drive with the sensor installed?
With a single carb, do you ever see significantly different readings between the sides? It seems like the mix would be the same for all cylinders, sampling that far down.
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= Si Opus Quadratum vis, angulos praecidere noli. =
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11-20-2009, 01:57 PM
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CC Member / Sponsor
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Join Date: Jan 2002
Location: Provo,
UT
Cobra Make, Engine: Daytona Coupe
Posts: 1,359
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Quote:
Originally Posted by cdnus
Tom,
Perhaps when you have a little time, could you please post more info on how to alter with expected results the transition circuit.
A few photos would be greatly appreciated also, for the carb challenged. 
Craig |
Sorry to have taken so long to post the pic.
In this picture I have put some paper clips pointing to where the idle restriction is. Please note: that Holley only uses one or the other location as a restriction, not both. Typically there is a brass slug that has a calibrated hole. This restriction controls your idle/transition circuit. You will need a number drill set and a pin vise. Measure the diameter of the hole before you start so you can go back...
http://www.mcmaster.com/#metalworkin...d-rods/=4l7tlr
drilling the jet bigger makes the circuit richer. Go in small steps...
Please note: that I only put pointers on one side of the block. The right hand side has the same restrictions.
As a side note: I have never seen this circuit too lean from Holley...
Last edited by Tom Kirkham; 11-20-2009 at 02:26 PM..
Reason: clarity, grammer
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11-20-2009, 02:17 PM
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CC Member / Sponsor
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Join Date: Jan 2002
Location: Provo,
UT
Cobra Make, Engine: Daytona Coupe
Posts: 1,359
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Not Ranked
The idle circuit is what determines for the most part what your fuel economy is at cruise. This circuit can be made quite lean. For example an air fuel ratio of 15:1 is not uncommon at cruise in modern engines. Please note: your engine will not be happy at an idle with an air fuel ratio this lean.
We have one of Keith Craft's 482 getting 15 MPG on the highway, with outstanding driveabilty. It just takes time... and a wide band O2 sensor.
Last edited by Tom Kirkham; 11-20-2009 at 02:25 PM..
Reason: clarity
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11-20-2009, 03:31 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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Not Ranked
Thanks Tom,
Not long at all.
I can achieve any A/F @ idle I want with the scews, but when I have it in a reasonable range 13.5-14.7 the cruise ( below 22-2300 ) will run as high as 16+. I keep tabs on the plugs & everything looks ok, pretty white but ok. As soon as I apply a little throttle it picks right up 13.5-14.5. The richer I run the idle the better the cruise is, But as you know there are limits to that.
Your mod--will it richen up & change the idle adjustments also, or will it just help out the transition?
I have 18000mi on the engine & get 22 MPG average.
Thanks again
Craig
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11-20-2009, 03:58 PM
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CC Member / Sponsor
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Join Date: Jan 2002
Location: Provo,
UT
Cobra Make, Engine: Daytona Coupe
Posts: 1,359
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Not Ranked
Quote:
Originally Posted by cdnus
... Your mod--will it richen up & change the idle adjustments also, or will it just help out the transition?
I have 18000mi on the engine & get 22 MPG average.
Craig
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Yes it will change both the idle and transition. So you will need to readjust your idle screws. Those are very impressive MPG numbers. |
11-20-2009, 05:05 PM
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CC Member
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Join Date: Nov 2003
Location: Carpentersville,
Il
Cobra Make, Engine: shell valley cobra-350 chevy
Posts: 62
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Not Ranked
My car is in storage now but I have been fighting an off idle hesitation all summer. Trying to gather info for spring. My question is, What is "idle eze"? I've been playing with 4150"s for a long time and never heard that term until lately when reading several different forums. Is it something on a 4 corner idle screw carb or what is it?
Thanks, Russ
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11-20-2009, 05:08 PM
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Senior Club Cobra Member
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Join Date: Jul 1999
Location: SF Bay Area,
CA
Cobra Make, Engine: SPF #1019
Posts: 1,657
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Not Ranked
As I understand it, as you lean out the A/F for cruising, you should/can increase ignition timing, and this can be done with a vacuum advance distributor <- this will increase fuel mileage w/o sacrifcing power.
Idle-eze is a feature of Demon carbs...
Last edited by Randy Rosenberg; 11-20-2009 at 05:11 PM..
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11-20-2009, 05:10 PM
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CC Member
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Join Date: Dec 2004
Location: toronto,
ont
Cobra Make, Engine: 408w 500 h.p. 550 ft.lbs
Posts: 562
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Not Ranked
Tom,
So the result would be simular to changing the air bleeds?
RE: MPG---22MP/imp.gal---in US gal.---17.5MPG not so impressive now EH! LOL
Thanks
Craig
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