71 Duster 360 turbo build

turbovan said
FYI I did have several clean pulls to 6k with this setup on the last engine. I’ve also taken at least one very solid 5500+(too rich) pull on this engine before the sensor went out. So I am focusing on sensor air gap and loose grounds at this point.

Sensor mount is very solid right between two bolts on a 1/8 steel bracket. However, it it IS inches from the alternator. Not optimal but again it was working fine until suddenly, and without any changes, it started having sync issues.

View attachment 1716024949

View attachment 1716024950

The alternator mounts through that gap between the two brackets.

I run the red cherry sensor as well. I had a similar setup as you with the trigger wheel welded to the steel pulley. I originally had just a few tack welds holding it on because I didn't want to add too much unbalanced weight to the pulley. One day I developed a high RPM sync loss on my MS3. Initially, I thought I was hitting the rev limiter until it got worse and started happening more frequently and at lower RPM. I soon figured out that a tack weld on my trigger wheel had cracked. I guess the wheel would start floating at high RPM. I fixed the one cracked weld and it happened again. This time I completely welded the trigger all the way around. It never happened again. I'd check your welds and your runout on the wheel. You also mention above that you had the air gap at .059". That's a lot. Also shown above is the spec sheet that says 5mm max, which is .0196". I've since redone my setup with a serpentine pulley. I believe I ended up around .026" and it's been running great. Spins to 6800 no problem.