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Posted by: Van B Mar 8 2022, 09:48 AM

Does anyone have an exhaust gas analyzer they would be willing to rent me for a reasonable fee?
I need to do some AFM checks and tuning and don't think installing a wideband sensor is feasible given the age and rustiness of my original exhaust. I'm afraid that things will get out of hand if I start grinding and cutting on the muffler to install a sensor bung.

Bought and waiting to be used thanks to troth.

Posted by: troth Mar 8 2022, 01:00 PM

I have a CO meter that I got for free. It’s a real POS piece of plastic junk. Doesn’t seem to like to hold calibration. I tried it on my car and it helped to get the tune close, but there was always doubt if I was spot on or not. If nobody steps up with a better deal you can have it for $10 to cover the cost of shipping.

Posted by: Van B Mar 8 2022, 01:10 PM

Is it an old school style with the swing needle? I'm pretty sure those have to be calibrated before every use typically.
I was originally looking to buy a Heathkit CI-1080 but those have become expensive an rare novelty items it seems.

As long as it works and its reasonably accurate, I'll gladly accept. The manual says CO should be between 2 and 3% lol... that's a pretty wide range compared to modern vehicles.

Maybe someone else will respond with a different device and I'll have the luxury of doing a back to back comparison!

Van

Posted by: StarBear Mar 8 2022, 02:22 PM

@http://www.914world.com/bbs2/index.php?showuser=8571 B. How could one calibrate it? Wouldn’t some standard (bottle?) gas be needed? If it works I’d be interested in borrowing it. We could exchange at the July NE Gathering.

Posted by: infraredcalvin Mar 8 2022, 03:50 PM

You may want to try one of these, it allows you to use a wideband afr sensor without installing a bung.

https://www.innovatemotorsports.com/xcart/exhaust-clamp-p-n-3728.html

Posted by: BillC Mar 8 2022, 04:15 PM

If you already have a wideband O2 sensor, you can "simulate" a probe-style sensor by taking a foot or so of 1" - 1.5" steel tubing, welding a bung onto it in the middle and then clamping the pipe to your exhaust outlet (stick as much inside the exhaust as you can).

Posted by: troth Mar 8 2022, 04:45 PM

This is it here. Says accurate within 0.5% but I’m not sure I believe it. PM me your address. I can put it in the mail tomorrow.



It’s calibrated by putting it in clean, exhaust free air and setting it to 2%.

Posted by: Van B Mar 8 2022, 04:53 PM

After the elements warm up completely, you're supposed to balance the needle while both sides are exposed to air. Then the difference in cooling between the air side and exhaust side is shown as your CO level.
These devices went out of fashion because this method really needs time to get a reading and for the engine to hold a static setting.

Posted by: Van B Mar 8 2022, 04:55 PM

Ooo a Gunson! Heck yeah man! PM headed your way.

Posted by: Van B Mar 8 2022, 04:59 PM

@http://www.914world.com/bbs2/index.php?showuser=9463 @http://www.914world.com/bbs2/index.php?showuser=18667
Thank you for the idea!
I don't have an O2 sensor and the OE tail pipe is pretty small diameter. Too small for the depth of a Bosch sensor. But it's definitely an idea worth exploring in the long term. I'd rather have a new exhaust with a bunch installed though. Hopefully, I can get this car running to my satisfaction soon and then have time to spend on enhancements.

Posted by: BK911 Mar 8 2022, 05:00 PM

I have used a gunson on dozens of cars with repeatable results.

Posted by: StarBear Mar 8 2022, 07:46 PM

Neat. We gots the time.

Posted by: Van B Mar 8 2022, 08:09 PM

This one operates nearly the same way as the Heathkit swing needle style but has a basic digital display and has air flowing over the reference element to help speed the analysis… still has to be calibrated every time it’s powered on, but I think it will be so cool to go through the same tuning process as folks did when these cars were new!

Posted by: targa72e Mar 8 2022, 11:10 PM

My .02cents.
Get a good wide band 02 sensor and tune with that. Who cares what idle mixture is if wide open or part throttle is way lean or rich. Use wide band and drive around and tune for best compromise.

john

Posted by: mgp4591 Mar 9 2022, 01:13 AM

We used a propane enrichment calibration for ours. The propane has a relatively constant level of HC so we'd dial into that, then stick it up the tailpipe and find out what the variable was. Pretty sure most of the early swing needle models were about the same.

Posted by: StarBear Mar 9 2022, 08:49 AM

My other option is to take it to my local garage with state emissions testing and a screwdriver for the CO adjustment screw. Not as much fun or learning, though.