Re: affordable air/fuel ratio monitors?
[Re: Adam71Charger]
#1805665
04/17/15 02:22 PM
04/17/15 02:22 PM
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Joined: Jan 2003
Posts: 13,031 Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 13,031
Benton, IL.
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If narrow band will do, that is a good suggestion. Pull any 4 wire sensor (or better yet get a couple) from a late model wreck for $10 or so, and get a guage for $30 or $40. You will only need 2 wires from the guage to the sensor so you'll have to wait for the sensor to warm up since it won't have heater voltage, but that's no big deal.
In the right hands, the cruise can be tuned as well with the narrow band as with the wide bands.
Master, again and still
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Re: affordable air/fuel ratio monitors?
[Re: DaveRS23]
#1805682
04/17/15 02:47 PM
04/17/15 02:47 PM
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Joined: Jun 2008
Posts: 10,958 Oakdale CT
gdonovan
I Live Here
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I Live Here
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Oakdale CT
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In the right hands, the cruise can be tuned as well with the narrow band as with the wide bands.
Cruise is extremely accurate with narrow band, it is the sweet spot (14.7-1 ratio) for sensor accuracy. 11-1 or 12-1 ratios are on the outer edge of the sensors resolution and care has to be taken when running up to the ragged edge. I have done it with great success but did make an ashtray with one engine running 20 psi till I found out how far you could push it. Also excellent for watching circuit transitions, tuning with an O2 gauge is such a pleasure. No guessing as long as you are aware what circuits are currently in play (vacuum gauge valuable tool here) and when the next comes into the picture. Typical Carter for example on primary side would be Idle Circuit -> main jet metering rod down -> main jet metering rod up. With the vacuum in the intake determining when you go from cruise to WOT on the metering rod. Watch when pressing on throttle to see if there is lean spot or excessive fat bump (accelerator pump shot) Once primary is right hook up the secondary linkage and hit WOT to check mixture. Adjust secondary mixture as needed.
"I think its got a hemi"
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Re: affordable air/fuel ratio monitors?
[Re: Adam71Charger]
#1805698
04/17/15 03:32 PM
04/17/15 03:32 PM
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Joined: Jun 2008
Posts: 10,958 Oakdale CT
gdonovan
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I Live Here
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Im a little confused, will a 4wire sensor be compatible with a 2 wire gauge? Narrow band come in three flavors- Single wire = output with ground through shell 3 wire = output with 12V and ground for heating element, sensor still grounds through shell. 4 wire = output with 12V and ground for heating element, sensor grounds through 4th wire. Most gauges have sensor input, ground and lead for dash lights. All the carb cars I have done use a 3 wire sensor installed down in the header collector. Being heated they warm up in 10 seconds flat and you don't have to worry about them getting sleepy if idling for extended period of time. 3 wire were used by mamopar from late 87 to early 89.
"I think its got a hemi"
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Re: affordable air/fuel ratio monitors?
[Re: BigBlockMopar]
#1805771
04/17/15 05:26 PM
04/17/15 05:26 PM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Because intakes can be designed badly that one side of the engine or a few cylinders need to or less fuel than the rest.
I've got 2 sensors and gauges mounted in my dual carbed longram intake engine. While this ofcourse can almost be seen as two seperate engines, still the amount of variations between the carbs and engine sides is interesting to say the least.
Point taken. However Most guys are running good, aftermarket intakes. A long ram intake is an extreme example. I have heard of some 6-pack guys running staggered jetting as well but again not common. With a single 4bbl with central located jets to feed 8 cylinders there's only so much playing you can do.
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Re: affordable air/fuel ratio monitors?
[Re: Adam71Charger]
#1805818
04/17/15 07:11 PM
04/17/15 07:11 PM
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Joined: Jun 2008
Posts: 10,958 Oakdale CT
gdonovan
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I Live Here
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If doing a single sensor consider an H-pipe and mount in the center.
"I think its got a hemi"
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Re: affordable air/fuel ratio monitors?
[Re: gdonovan]
#1805831
04/17/15 07:33 PM
04/17/15 07:33 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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Posts: 16,376
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This is, certainly, much ado about nothing. Narrow-band sensors are only accurate about 0.5 on each side of stoichiometric. If you're already there, then they can be helpful.
Also, with a 4-wire sensor it's so easy to run power to the sensors and get them to operating temperature. Just one wire to switched 12VDC and one wire to ground. As the sensor heats up the resistance goes up and current flow decreases to almost nothing, so there is no need for a control circuit on the O2 sensor heaters.
As far as wide-band vs. narrow band, when the cheapest wide band sensor was $200, maybe it made sense to just have one. But nearly every new car has them, they many times have a U-shaped connector plug and 5 wires, like my wife's Hyundai. The new sensor is around $100 from Rock Auto. For the JY scroungers, many of the 4-cylinder FWD cars have the O2 sensor stuck right in the middle of the exhaust manifold, right on front center of the engine. Pull it out by opening the hood, no crawling around on the ground.
This is an area where a newbie will be better off spending a little more time to get a product that is more user-friendly. Two sensors, data recording and playback can make life much easier for the novice.
One more thing: How many of you think that the right side of the carb feeds one side, and the left feeds the other side? In the case of long rams, yes, in the case of divided single planes, yes, in the case of my Weiand 7503 for the 318 Poly motor, yes, and for virtually everything else, NO. So the right bank exhaust is a combination of the right and left sides of the carb, as is the left bank exhaust. As was alluded to above, fuel distribution can cause many discrepancies from cylinder to cylinder and side to side.
Back in the day, the Direct Connect engine books were full of instructions on epoxying popsicle stick dams in the intake plenum to even out fuel distribution. Older data that I saw showed that most aftermarket intake manifolds had worse fuel distribution than the stock intakes, and as emissions laws got stiffer, the manufacturers stayed out in front. Port fuel injection cures a lot of those ills.
R.
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Re: affordable air/fuel ratio monitors?
[Re: dogdays]
#1805946
04/17/15 10:18 PM
04/17/15 10:18 PM
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Joined: Jun 2008
Posts: 10,958 Oakdale CT
gdonovan
I Live Here
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I Live Here
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Oakdale CT
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Also, with a 4-wire sensor it's so easy to run power to the sensors and get them to operating temperature. Just one wire to switched 12VDC and one wire to ground. As the sensor heats up the resistance goes up and current flow decreases to almost nothing, so there is no need for a control circuit on the O2 sensor heaters.
I have been doing this for decades. Chrysler never had a control circuit for O2 sensor heaters (can't say on newer vehicles though) key on and blam the sensors were always powered. For someone not pushing the ragged edge and on a budget narrow band is fine and for $30 and some junkyard parts you are in business. I did push the ragged edge for years at 20+ psi with nothing but narrow band and was very successful at it and it is a far less forgiving environment then n/a applications.
"I think its got a hemi"
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