Flathead tuning tool—— wideband 02 sensor

[35fordtn]

I have been contemplating doing this for a while. Carburetors run different from engine to engine and different on the road than on a stand. I bought a 02 sensor and gauge and mounted it with a cheap lithium 12v battery to be able to use on 6v cars. Used it today on a 34 Ford and worked flawlessly. I was able to see it was a tad lean at idle and rich under load.




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[flatford8]

Did you put a bung in the pipe…..or how did you mount the sensor?…..Mark

[Kube]

Michael, You amaze me

[Bored&Stroked]

You want the bung in the pipe and hopefully no closer to the end of the pipe than about 4". Also, don't put the bung AFTER a joint that might be sucking in fresh air.

I like to be about 24" away from the block, with our typical 'Belond Style' headers, unless you add flanges or lengths to them, you might be closer.

I've found that under load, with my dual Stromberg 48's, I tend to have an AFR in the low 12's. A bit rich - but rich is safe! LOL

[38 coupe]

I got an Innovate brand unit several years ago, used plug in wire connectors so I could switch between powering the O2 sensor with a 12V cigarette lighter port or alligator clips onto a spare 12V battery, and set it up in a two gauge pod with a vacuum gauge. I expected to use the setup frequently, but haven't had the need. In the flat lands of Texas using stock carburetor jetting and stock ignition settings work with no extra need to modify things.


For the people who frequently use their O2 meter, what types of engines and what driving conditions do you find you use the meter?

[35fordtn]

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You do have to drill a hole in the exhaust and weld a bung. The bungs are available with a plug for around $3. I welded it at a roughly 80 degree angle around 10” before the muffler.

[35fordtn]

Originally Posted by Bored&Stroked

You want the bung in the pipe and hopefully no closer to the end of the pipe than about 4". Also, don't put the bung AFTER a joint that might be sucking in fresh air.

I like to be about 24" away from the block, with our typical 'Belond Style' headers, unless you add flanges or lengths to them, you might be closer.

I've found that under load, with my dual Stromberg 48's, I tend to have an AFR in the low 12's. A bit rich - but rich is safe! LOL

I’ve been aiming for 13.5-14 at idle, 12.5ish wide open at load and 13.5 normal cruising. My limited days in racing oval track late models make my small brain think this is a good combination, only time will tell.

[Seth Swoboda]

Great idea. I'd love to try this out on some of my flatheads. I'm looking forward to my next visit to 3rd Gen Automotive.

[Bored&Stroked]

Originally Posted by 35fordtn

I’ve been aiming for 13.5-14 at idle, 12.5ish wide open at load and 13.5 normal cruising. My limited days in racing oval track late models make my small brain think this is a good combination, only time will tell.

That is about right if you can obtain it. What I usually find is that it takes some tuning of the power-valve and main gets to attempt to get both cruising and full-power AFRs to be where you want them. In the end, I usually end up erroring a bit on the rich side as I'm not trying to race anybody. LOL.

These carbs are super simple, there aren't really a lot of circuits to tune or screw with.

[Bored&Stroked]

BTW, if you're welding/working on a set of headers, also put some EGT bungs as close to the block/ports as possible. You may never need them, but they are handy to have - so might as well put them in.

I usually do one in the middle (Siamese port) and one in the rear at a minimum (about an 1" from the block). It is handy to see the EGT temps in addition to the AFRs - especially if you're building a high-end boosted engine.

[Shoebox]

Originally Posted by 35fordtn

I’ve been aiming for 13.5-14 at idle, 12.5ish wide open at load and 13.5 normal cruising. My limited days in racing oval track late models make my small brain think this is a good combination, only time will tell.

Michael, that "suitcase" setup that you made for the A/F gauge and components is pretty neat. It would be informative if folks with A/F gauges would share what was done tuning wise to get from where they started to where they wanted to be. I look forward to installing the Auto Meter gauge I have and seeing where I initially come in.

[tubman]

I have an Innovate on my test stand and have a "sniffer" (one of those things that go up the exhaust pipe and clamp on). Since I only run headers and a short extensions, this puts the sensor in about the right place. I can get the engine to run 13.5-14.0 at speed pretty easily, but they all seem to idle best at 11.5-12.00. After messing around with it for a while, I decided it's the nature of he beast and live with it. From what I can see, the plugs look the right color.

The "sniffer" looks kinda like this one.

[34fordy]

[QUOTE=Shoebox: It would be informative if folks with A/F gauges would share what was done tuning wise to get from where they started to where they wanted to be.

YES

[1948F-1Pickup]

I'm not tuning a NASCAR engine.
This antiquated item does the job just fine.............
No bungs required.

[Bored&Stroked]

Process: If you think about it, it depends on the types of carbs you have and what idle, cruise and enrichment circuits they have. On both Holley's and Strombergs the idle circuit is easy - you turn a needle valve in until the engine starts to labor or struggle a bit, then you back it back out until it doesn't.

Important: With multiple carbs the first real step is to synchronize the air flow between all of them - you need something like a Unisyn to achieve this. If the air flows are not the same, then everything else will be different. If you have a progressive linkage (like with a 3 carb setup, then you must sync the outer two).

The main cruising circuit is controlled by the two main jets - you start with stock sizes (like 45's on Stromberg 97's), then you increase/decrease by two steps in the appropriate direction to change the rich/lean under cruise and load.

The FINAL load tune is the mechanical power-valve in the bottom of the accelerator pump well. This (unlike a Holley) is strictly actuated by the bottom of the accelerator pump plunger. When the throttle is more toward wide-open, this additional enrichment circuit is opened. These power valves come in different numbered sizes just like the main jets - though the SMALLER number the richer the enrichment (backwards from the mains).

On the accelerator pumps, there is no adjustment on true Stromberg 48's (for the push-rod), and on Stromberg 97's I usually use the outer ball - always seems to run better with more of a squirt.

Okay, enough out of me . . . time for a glass if vino . . .

[tubman]

So far, I have used mine to tune only Rochester 2G's. This may explain the differences between my numbers and Michael's.

[Mart]

I used a wide band sensor when I set up the twin 94s (actually 2100s) on my "big inch" flatty. I found I was quite lean. I ended up with 54 jets. I didn't have any so drilled out some otherwise useless 46s. I bought a set of small drills from a hobby shop and used those.
The gauge takes all the guesswork out of the job.

[Ken Henry]

I was running two 94s converted to EFI throttle bodies so the mixture was easily adjustable with a laptop. Max AFR I could run at idle was 12.5. I set WOT idle in the high 12s based in something I read in JWL’s book. Ken

[Bored&Stroked]

Originally Posted by Mart

I used a wide band sensor when I set up the twin 94s (actually 2100s) on my "big inch" flatty. I found I was quite lean. I ended up with 54 jets. I didn't have any so drilled out some otherwise useless 46s. I bought a set of small drills from a hobby shop and used those.
The gauge takes all the guesswork out of the job.

How many carbs are you running and did you also screw with the vacuum operated power valves? Having them open at the right time is quite important for getting the mixture right for heavy load conditions when the vacuum drops and enrichment is needed.

Stock power valves usually open too early in multi-carb setups - but one needs a vacuum gauge to figure it out. Also, one needs the correct power-valves - from folks like Daytona Carburetors - as most of the "modern ones" leak and have issues in our older 94, 2100, 2110 carbs.