Air/Fuel Reader and O2 Sensor Advice

[sfdaugherty]

I also use AEM on my Solex car.

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[Curtis]

Thank you so much for the information. I searched for reviews on handheld last night and the Innovate came up. Not cheap but good reviews.

I temporarily had a temperature gauge in that location. I could put one there until I get it sorted out. After three distributors, three sets of needles, and two sets of carbs the problem persists. Current thinking we're discussing is the carbs may not have enough for the stroker in the 3 to 4k rpm range where the problem is. The richer needles and turning up the mix helped some along with the pulling the choke trick.

Going to put the U20 SU on it and see what happens. Days that I can drive will be limited now that Fall has finally decided to arrive here.

As for the bung I have an easily removable head pipe at the header. You can't get the stock pipe out with header or manifold in. I suppose I could take in and have one done but I can do it myself in an hour or two.

[Gregs672000]

All kinds of great info already given. I agree that it will work much better with a bung vs tailpipe adaption. The gauge can be stuck anywhere temporarily with double sided tape etc, or put it in a small mount. Systems vary, but my Glowshift uses a control box and a separate gauge. Wiring is simple so you can find places to splice in to the existing wiring. They come complete using a high quality O2 sensor. I do suggest testing while driving. My EFI system has "autotune" capability, and the numbers will change significantly in the low load cells if I just rev it up in the driveway vs actual driving. As noted, there is only so much you can do regarding ratio with an SU carb. Any decent name brand wideband should work fine for what you're doing, so spending a lot more money is up to you... Higher accuracy and super quick response is far more important to computer controlled feedback systems like EFI and is not needed for a carb.

Curtis, another thing you may want to check is how much total ignition advance the distributor is giving at the rpms where you are having issues. A timing light will be needed. From what I understand, it should be "all in" at 3000-3500rpm and up... as high as 36 degrees with the vacuum advance hooked up and under light loads, less under load as the vac advance is reduced... 32 degrees or so?

I think you're going about this the right way, frustrating as it is. It's either fuel ratio, not enough air, ignition timing or a cam profile. Unfortunately it can be a little from box A, some from box B, etc... all you can do is check each one as thoroughly as you can to eliminate or be aware of each factor and then see what you can do about it.

[Curtis]

Advance and valve adjust were done. Dave F. is helping me.

[Gregs672000]

You mentioned that the engine is "going flat" at 3000 rpms. Is this under all loads, medium loads or high loads? Does it ping? Can someone drive behind you to see what comes out the tailpipe when you hit It? What do the plugs look like in general? On the dyno, you see very little HP changes with fuel ratios until they get into the 16s (lean) or below 11.5 (rich). Throttle response will change... rich usually being just plain flat, lean with a surge then hesitation. An SU carb controls sudden acceleration ratios using the damper oil so the piston doesn't slam open. A different oil may make some changes here, but we're getting way far from my experience and others will be better at the nuances of this.

I'm inclined to believe that the larger 2 liter SUs may be the answer.

[Daryl Smith]

Irrelephant

[Curtis]

FYI - I just replaced my wideband O2 setup (MTX-L). The newer Bosch sensor is a LSU 4.9 (replacing LSU 4.2) a longer 1" bung is recommended for the new sensor which takes the sensor tip just out of the exhaust stream. The 4.9 is supposed to work better and last longer than the 4.2. *I have no info on other O2 sensors, or aftermarket controllers that may use them.

A narrow band sensor will only tell you if you are lean or rich of 14.7:1 fuel ratio, but, not by how much. "Rich" at say 14.2 is still way too lean for WOT. "Lean" of 14.7 can save you some fuel and is fine for cruise, to a point (different point on different engines), but, requires a good ignition system to light the leaner mixture. Going lean at higher loads will lead to burnt rings and piston failure.

I found the following on ebay.

Bosch O2 Oxygen Sensor 0258017025 LSU 4.9 Lambda Wide Band Fits AEM 30-4110 UEGO

[Daryl Smith]

Irrelephant

[Curtis]

I'm assuming you've checked over the ignition system? Coil, plugs/gap, plug wires, etc? As they say, often, a supposed fuel issue ends up an ignition issue and vice versa....

As I recall, there are several people running the 1600 carbs on strokers without issue....What is different with your engine? Bigger cam? ....??

All been checked. New plugs, valve adjust. Fuel pump checked including putting clear fuel tube on to make sure there is fuel. Stock, matchbox and 123 distributors. Street grind cam. Thought it was mixed cam gears but it was not.

So the sensor I found on ebay? Is that the one?

[Pjackb]

Thank you so much for the information. I searched for reviews on handheld last night and the Innovate came up. Not cheap but good reviews.

Check classifieds, I got mine off FB Marketplace for 250$cdn and it was basically new

[Curtis]

Don't do any social media, especially facebook. Only facebook I care about is a photo album.

[Gregs672000]

So it sounds like it doesn't just go flat momentarily, but doesn't want to rev very much past 4000? Is that correct?

[Daryl Smith]

Irrelephant

[Curtis]

Was looking at this one. I'll put the gauge in a box.

https://www.amazon.com/AEM-30-4110-UEGO ... e904010ad0

[Daryl Smith]

Irrelephant