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-   -   air/fuel mixture and air fuel gauges questions (http://www.hotrodders.com/forum/air-fuel-mixture-air-fuel-gauges-questions-163382.html)

tomcraft 08-14-2009 10:31 PM

air/fuel mixture and air fuel gauges questions
 
thanks for your anticipated help im new to hotrodding and i need some help i have a 383 with an edelbrock carb 750.the car is running it seems a little rich.i was thinking of installing an air fuel gauge.The questions i have is where should i put the oxygen sensor ?how to best install it?is this a good idea?whats the ideal ratio?it seems to me that having a gauge would be great especially if i add forced induction but i dont see many cars with them wonder why thanks again

saitek5678 08-15-2009 02:00 PM

saitek5678
 
Have you adjusted the floats?, WOW just talked about this with another subscriber. On the top there is a screw with a nut, turning the screw out will lower the fuel level in the float bowl,is it a four barrel? in that case there will be two. Try dicken with that and then the idle air adjustment screws.

saitek5678 08-15-2009 02:06 PM

saitek5678
 
Oh its a edlebrock carb , Which is probley a Carter, sorry! Anyway try turning the idle air screws in,quarter turn one side at a time, it should lean it out till the engine kills if not something else is wrong. check if there is a external float adj.

Soul_Hunter 08-15-2009 02:25 PM

as a general rule, you want it at least 18 inches from the nearest exhaust port on the heads. i believe some companies say 24 inches.
a wideband O2 sensor will have a heating element so it really doesn't need exhaust heat to work properly.
it can not be installed behind the cats if you have them.
you can't have any exhaust leaks between the motor and the wideband sensor or it will throw the readings off. also you don't want an exhaust leak right behind the sensor, i feel at least 2 feet of pipe behind the sensor is enough for most motors.
one with a gage is fine, but i would recommend getting a wideband that you can also data log to a laptop with. its not the safest thing to try to watch a gage while your driving.
you can hook up a MAP sensor and RPM input and know where the motor is at during the range of acceleration and cruise by watching the log file after a run.
you can get a bung and have it welded into the pipe.
i think most people don't have a wideband because of the price, a good WB isn't exactly cheap. but they are cheaper than a cooked motor.

each motor is a little different, so the AFR thats ideal for one motor may not be optimal for another.
at WOT, its better to be a little rich than a little lean. without forced induction, starting around 12.5:1 should be ok and then work from there.
i've never messed with forced induction, so i don't know what you would want to start at with it.

tomcraft 08-15-2009 02:52 PM

thanks so much,if anyone has more thought on this would appreciate.any brand better than others?

litdoc 08-15-2009 03:26 PM

?? air/fuel mixture
 
Hi Tom, for best economy and smog test AFR of 14.7 is best but again you have to be careful as this will be very hot burning. I usually back off to 14.5 for everyday driving. When I want max economy I will lean it out to 14.7 but keep an eye on the AFR meter or exhaust gas temp sensors if the car has them.

bentwings 08-15-2009 08:17 PM

I have an Innovate on my rod. I just installed it so I don't have a lot of info on . They have a great forum on their web site.

75gmck25 08-15-2009 09:09 PM

One reason you don't see many AFR gauges installed is that a good one with a wideband sensor will usually cost about $300 or more. This is outside the price range of most folks, unless they have deep pockets.

Edelbrock also makes a fairly cheap AFR gauge that several places sell, but it won't be as accurate as the ones that use wideband sensors. As someone else mentioned, it also probably does not use a heated sensor, so it has to mounted fairly close to the engine where the exhaust heat will keep it hot.

Bruce

ericnova72 08-15-2009 09:13 PM

Lowest emissions may be true at idle at 14.7-1 AFR, but for economy you need to be up in the 15 to 16-1 AFR at cruise. Most modern F.I. engines go this lean at highway cruise.

recklessnova 08-20-2009 08:39 AM

I have the fast wide band setup that has two sensors one for each bank and have been using it to tune with for the past two years or so I will never not have a wideband setup on a carb car agian It makes it so easy if you know what to watch for
Fast just came out with a new wideband setup that uses a gauge and i think its around the 180 range Mine was 3-400 or so when i bought it
I have a edle 750 on a little 355 in my nova and by using the wideband I have been able to get highway speed low load upo to 17 to 1 with no problems and when I go wide open It settles at 12.1 give or take a .1 depending on the weather its about perfect car runs 110 in the 1/4 and gets about 22 to 24 on the highway
Just my thoughts
Josh

bentwings 08-20-2009 11:40 AM

I'm new to the AFR but even old foggies can learn. I'm learning fast.

So far I haven't been able to get it down to the lean area and still get the performance but I'm working on it.

I had 12 inches of vacuum at idle which is what Edel. told me I should have. In tuning with the Wband I found that I was going right past the point the point where the vacuum picked up. It amounted to about 1/8 turn on the idle screws. There is no other indication from the motor , just the WB starts to go up to around 13.6-13.8. Turn the screws +/- 1/8 or more and it drops at least .5 and vacuum drops 2 inches.

The next step will be to add data logging, Map and TPS. These cost about 6 pulls at the dyno shop. However I can make as many runs as I want with the data logger. So the logger will be more valuable than the dyno for now.

I think it will be really valuable when I get to the blower. Hopefully there is someone aroun dwho has done work with the AFR and blower.

I just picked up my new blower today so it will be a reality shortly.


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