I have had the 123 for a few months now, measuring the dwell angle with my Innova 5568 shows 22 at idle with a maximum of 66 degrees.

Is this expected when the dwell on a stock distributor is between 44 and 50 degrees?

Dwell angle isn’t measured with mag pickup distributors. It’s not going to reflect Factory specs. Dwell angle is more useful for determining points and distributor lobe wear.

Thanks Mr. Lee.

I'm at my wits end trying to determine why the engine is bogging under moderate to heavy acceleration... and honestly do not know where else to check.

Which unit have you got?

We’re the symptoms there before you installed the 123 distributor?

I don't remember this particular issue being a problem.

October last year I was attempting to resolve a hunting idle problem. I'm not convinced the distributor is the problem but I guess my next step would be to check the MPS again and reinstall the original distributor. I could also install my backup TPS, but am coming around to doing the same things many times over.

I only use the 123 Bluetooth unit, which allows incremental advance curve manipulation at various loads, and RPM. It sounds like you need to try a different advance curve.

I doubt the stumble is being caused by the distributor. Since you mentioned MPS...Engine stumbling/bogging can happen if the AFR is too lean.

Or too rich.. Either one.

This weekend I tried advance curves 1 - 7 and B, with similar or more bogging, I'm currently on curve 2.

I just checked the MPS and it held steady at 10 in Hg for over 10 minutes, I will check the resistance across both coils next.

I also ran the car with the TPS disconnected and it definitely accelerated more smoothly but the bogging(hesitation) is still present at ~2800 RPM and ~3600 RPM just not nearly as noticeable.

I have a second TPS and will install/calibrate that as well.

It also sounds like I need to have the AFR checked, I'm due for a safety inspection and will bring it up to the owner of the shop.

One last observation: the idle is not hunting as it was before, it is oscillating between 920 to 980 RPM. In a previous post I replaced all vacuum lines and also repaired a crack in the plenum and replaced the intake runner hoses.

Thank you all for the responses.

Question the CHT sensor.....

I checked the CHT at 72 degrees F (at the cylinder) measured 1.57 k Ohms
@ 100 degrees F the resistance did not register.

This is a relative new sensor (<5000 miles) but it is probably 6 years old. I know the CHT has a lot to do with cold start, would this also cause bogging / hesitation under acceleration?

And one last question I"m assuming in my 75 with a 2.0 L D-Jet I should purchase the 0 280 130 003/012 sensor which 2.94 K ohms at 68 degrees F

I ordered the 0280130012 from 914 rubber...

Thank you

Learning by trial and error is not the fastest way to learn.

So I learned that you cannot check the CHT when the car is running, today I checked the CHT and it appears to be in spec:
62 F - 3.86 k Ohms
143 F - 0.307 k Ohms

In an effort to understand why the engine is not idling smoothly I started to push/pull the (NEW) plug wires while the car is running. The idle would increase when I pushed in #4 wire, turns out the that new wire was not tightened, I trimmed the wire and secured the plug to the wire.
I was still experiencing the change in idle when touching the plug/wire and decided to pull the plugs and replaced them with another. The engine ran better but was still bucking/stumbling on acceleration.

I tried different plugs and my observations:
W175T2 - engine bogged quite a bit, plugs were black after a ~200 miles
W7CC - engine accelerated better but still a slight stumble
W7DTC - triple point - engine accelerates great, I'm still working on adjusting the idle

So I learned several things, do not trust new parts the plug wires and plugs were new. The spark plugs have a larger impact on the engine performance then I originally realized and will search the forum for plug recommendations. I will spend more the next time I purchase spark plug wires or just rebuild the ones I have with better wire.

Lastly I determined that the problem is actually the spark plug wire and not the plug wire ends or the spark plugs. I replaced it with a 7 mm wire I had built earlier this year. I set the distributor to curve B, attached the vacuum port to the idle circuit on the throttle body and reset the time timing to 27 degrees at 3500 RPM.

The engine idle was never this stable and there is no longer any stumbling or bogging, engine has never run this smooth