Can get my mixture rich enough- Weber 44 IDF |
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Can get my mixture rich enough- Weber 44 IDF |
tornik550 |
Jun 10 2012, 08:05 PM
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#1
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Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
Just installed a innovate air fuel gauge. I have always suspected that my mixture was lean. The gauge now confirms it. At idle my readings are about 10.5-11.5. At 4k rpm the readings are about 12. Of coarse, when I let of the throttle, the numbers go up to around 13. I have played around with the setting quite a bit- the changes do make changes however still not getting me close. Here is what I have- dual weber 44 idf's 60 idles (lean even with three full turns of the idle mixture screw) 150 mains 190 air f11 tubes (I don't remember what I set the float height to- 11mm? however I don't think that would mess up my idle mixture?) 2258 engine scat 45 cam (.507 lift, dur 262 at .050") 9.5:1 CR 2.0l heads 44intakes 38 exhaust my three theories- -just need to keep going up on jet size (just seemed like mine were getting a bit big) -float issue may actually effect idle mixture? (doubt) -possible that my gauge is wrong. I see no reason to believe that. I had just calibrated it and it is installed correctly according to the instructions. |
messix |
Jun 10 2012, 08:13 PM
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#2
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
isnt it the higher the number the leaner, the lower the richer?
i suspect you are very rich at idle. |
tornik550 |
Jun 10 2012, 08:18 PM
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#3
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Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
isnt it the higher the number the leaner, the lower the richer? i suspect you are very rich at idle. That was my understanding- that high is lean and low is rich. I also thought that 7.4 was perfect, higher is leaner and lower is richer. Not sure but thats what I thought. |
messix |
Jun 10 2012, 08:27 PM
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#4
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
gasoline
14/1 is ideal = idle and cruise 12/1 is under full load. e85 is down to around 10/1 ideal and 7/1 full load |
messix |
Jun 10 2012, 08:34 PM
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#5
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
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tornik550 |
Jun 10 2012, 08:39 PM
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#6
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Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
gasoline 14/1 is ideal = idle and cruise 12/1 is under full load. e85 is down to around 10/1 ideal and 7/1 full load Not sure how I screwed that one up. Damn. Thank you for pointing that out for me. I've posted here 565 times, only about 3 posts were half way intelligent. I think I need to go on a posting hiatus. |
messix |
Jun 10 2012, 09:25 PM
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#7
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
gasoline 14/1 is ideal = idle and cruise 12/1 is under full load. e85 is down to around 10/1 ideal and 7/1 full load Not sure how I screwed that one up. Damn. Thank you for pointing that out for me. I've posted here 565 times, only about 3 posts were half way intelligent. I think I need to go on a posting hiatus. post more learn more then teach more |
mrbubblehead |
Jun 10 2012, 09:30 PM
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#8
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Twodollardoug Group: Members Posts: 1,155 Joined: 17-December 10 From: calimesa ca. Member No.: 12,492 Region Association: Southern California |
actually you want to lean out your idle and cruise as lean as your engine will let you. 15:1, 16:1, 17:1. thats how you get your mpg up.
WOT you want in the 12:7 - 13:5 stoich (14:7) is the death zone. that is where cylinder pressure and egt is at its highest. |
messix |
Jun 10 2012, 09:50 PM
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#9
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
actually you want to lean out your idle and cruise as lean as your engine will let you. 15:1, 16:1, 17:1. thats how you get your mpg up. WOT you want in the 12:7 - 13:5 stoich (14:7) is the death zone. that is where cylinder pressure and egt is at its highest. please explain and support. |
Andyrew |
Jun 11 2012, 12:40 AM
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#10
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Spooling.... Please wait Group: Members Posts: 13,376 Joined: 20-January 03 From: Riverbank, Ca Member No.: 172 Region Association: Northern California |
actually you want to lean out your idle and cruise as lean as your engine will let you. 15:1, 16:1, 17:1. thats how you get your mpg up. WOT you want in the 12:7 - 13:5 stoich (14:7) is the death zone. that is where cylinder pressure and egt is at its highest. please explain and support. He's claimed this before... But I dont agree. Theres a damn good reason why new car manufacturers tune to stoich... |
ArtechnikA |
Jun 11 2012, 04:09 AM
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#11
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
QUOTE Theres a damn good reason why new car manufacturers tune to stoich... Yes - they have water-cooled engines and EPA mandated mpg requirements... But seriously, there are at least three driving regime numbers you need, not just two, and that makes tuning carburetors a challenge. Lean at idle is good, since there is no load. Keeps plugs clean and mpg good, since if you're sitting still, miles is 0 and fuel flow is something. WOT - every engine will be a little different (there's that tuning thing again) but something in the 12-13 range is typical. Unless you are driving at Daytona or Talledega, you don't spend much time there. The other number, the one you feel every day, is cruise. Some steady load part-throttle value probably between 3000 and 4000 rpm. Here is where you really have to pay attention. You get best efficiency at or lean of stoich - but heat is a factor. This is really a factor on Webers, and -really- on something as big as a 44, because at part-throttle cruise, you're probably not on the main jets yet. So you need idle jets that can keep the engine happy at cruise and not bo so stinky-rich at idle your eyes burn from the fumes... Go too lean at idle and it'll be hard to get off the line without bogging, especially with 44's. Accel pumps will be your big friends here. |
FourBlades |
Jun 11 2012, 07:36 AM
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#12
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From Wreck to Rockin Group: Members Posts: 2,054 Joined: 3-December 07 From: Brevard, FL Member No.: 8,414 Region Association: South East States |
14.7 is stoichiometric for 100% gasoline. 14.13 is stoichiometric for 90% gasoline 10% ethanol that is prevalent everywhere in the US now. John |
GeorgeRud |
Jun 11 2012, 07:48 AM
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#13
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Advanced Member Group: Members Posts: 3,725 Joined: 27-July 05 From: Chicagoland Member No.: 4,482 Region Association: Upper MidWest |
I think that the problem with the 44 mm size carbs is that they don't really provide enough of a draw through the venturis with a stock engine, especially at idle, so they never really run correctly. The Weber book seems to indicate that a 40mm carb throat is a more appropriate size for a street engine.
The effect of the ethanol in gas and the change in the correct air:fuel ratio is something I hadn't really considered, but it certainly would make sense. And I only thought that ethanol destroyed old cars by dissolving o rings, gaskets, and plugging up fuel filters! |
brant |
Jun 11 2012, 07:57 AM
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#14
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914 Wizard Group: Members Posts: 11,624 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Definitely 12.3 - 13.1 at WOT, especially at redline
watch what the last 1500rpm do as you approach redline usually a motor is leaning out more and more don't let it hit lean at redline as that is where most of the damage is going to happen... better to run a little rick in the 4k range if it means avoiding lean at the redline |
edwin |
Jun 11 2012, 08:02 AM
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#15
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Member Group: Members Posts: 321 Joined: 20-May 09 From: Australia Member No.: 10,384 Region Association: Australia and New Zealand |
As i understand 14.7 is full burn of all entering fuel.
No point in adding more fuel than is needed for cruise and idle which is why it was recomended for lean. Richer than stoich will give more power just leaves some fuel unburned which helps cool everything while working hard. Allows more choice of timing. How many cars now tune for stoich? sure some of the time but not for all running conditions. Cheers Edwin |
rhodyguy |
Jun 11 2012, 08:15 AM
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#16
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
whether they are 40s or 44s the venturi or choke size is important depending on the application. the size is usually on the top of the venturi and can be seen with a flashlight without breaking down the carbs. 34, 32, 28 etc and can be changed out to suit your needs. for a stockish 2.0 engine the 28s give good throttle response and little to no bogging.
k |
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