Small "update"
Been a minute since my last update. I haven't forgotten about the Coronet or the website. Life happens.
I recently completed "functional" portion the ignition conversion. The ancient MSD 6 removed and a 4 pin HEI module now doing duty. It works beautifully and the car now starts instantly. Previously it would often crank slightly longer than I thought it should and even die after a second. I suspected the MSD was the culprit but could never convince my friend to do the conversion or replace the 30+ y/o MSD box. All that remains on that front is wiring cleanup but that's on hold as there are several other underhood wiring issues to attend. I dislike doing and redoing things. Do it once, do it right, move on.
Unfortunately a few weeks previous to the ignition conversion the car developed a slight and barely perceptible stumble while cruising. It got progressively worse over time, to the point the car is undrivable. Symptoms: Car starts great, idles smooth, revs clean and strong, no hint of a miss or stumble. Once it warms up things go to crap. Idle is smooth and still revs clean and strong with instant throttle response, but it's all over the place during steady throttle. I suspect an exhaust leak at the right side collector gasket.
Quick EFI lesson. An EFI engine starts in "open loop" ignoring the O2 sensor/s. It begins using input within a second or so after starting in the case of an OEM system, usually a longer delay for an an aftermarket conversion. My theory is it idles clean because its a very small leak and not changing the AF/r enough to matter. It revs clean because acceleration enrichment is programming dependant in this system, effectively "open loop". At steady RPM above around 1500, the exhaust flow is creating a syphon effect, pulling air into the exhaust and throwing the AF/R way out. My O2 sensor is a few inches behind the right side collector...
Yes I'm guilty of very in depth diagnostics before turning a wrench or buying parts. ;)
And finally. I've located a 3.23 sure grip diff for swap for my 3.91. One of my closest friends and a Mopar fanatic in the best AND worst sense has the 3.23 unit as a spare for his 71 Cuda. Can't get luckier than that.
Happy and safe motoring!
Been a minute since my last update. I haven't forgotten about the Coronet or the website. Life happens.
I recently completed "functional" portion the ignition conversion. The ancient MSD 6 removed and a 4 pin HEI module now doing duty. It works beautifully and the car now starts instantly. Previously it would often crank slightly longer than I thought it should and even die after a second. I suspected the MSD was the culprit but could never convince my friend to do the conversion or replace the 30+ y/o MSD box. All that remains on that front is wiring cleanup but that's on hold as there are several other underhood wiring issues to attend. I dislike doing and redoing things. Do it once, do it right, move on.
Unfortunately a few weeks previous to the ignition conversion the car developed a slight and barely perceptible stumble while cruising. It got progressively worse over time, to the point the car is undrivable. Symptoms: Car starts great, idles smooth, revs clean and strong, no hint of a miss or stumble. Once it warms up things go to crap. Idle is smooth and still revs clean and strong with instant throttle response, but it's all over the place during steady throttle. I suspect an exhaust leak at the right side collector gasket.
Quick EFI lesson. An EFI engine starts in "open loop" ignoring the O2 sensor/s. It begins using input within a second or so after starting in the case of an OEM system, usually a longer delay for an an aftermarket conversion. My theory is it idles clean because its a very small leak and not changing the AF/r enough to matter. It revs clean because acceleration enrichment is programming dependant in this system, effectively "open loop". At steady RPM above around 1500, the exhaust flow is creating a syphon effect, pulling air into the exhaust and throwing the AF/R way out. My O2 sensor is a few inches behind the right side collector...
Yes I'm guilty of very in depth diagnostics before turning a wrench or buying parts. ;)
And finally. I've located a 3.23 sure grip diff for swap for my 3.91. One of my closest friends and a Mopar fanatic in the best AND worst sense has the 3.23 unit as a spare for his 71 Cuda. Can't get luckier than that.
Happy and safe motoring!
