AMC Eagle

[MadMan]

Vacuum gauge? That's interesting. When you said you added a tee to the vacuum port, I thought maybe it would've have a fuel economy gauge. Same thing, I guess lol.

This whole project reminds me of my Chrysler LeBaron. Which I got beat up and bone stock, I went to a lot of junk yards and scavenged a lot of LeBarons to get just about all the factory options.

[MIPS]

A vacuum gauge is pretty handy as a diagnosis tool but otherwise it will normally just wander between 20 and 5 inches of mercury most of its life as you accelerate and coast. Don't knwo why they settled on a 40 inHg scale. You'll never even touch 30.



The more head scratching thing is the package includes an analog clock, but if you already have the digital clock in the dash there's not a lot of purpose to it besides it just whirrs away constantly.
One thing that the harnes DOES help with in that matter is it adds the tachometer wiring which goes in the place of the digital clock. I have a salvaged one but they are apparently prone to failure. Mine on inspection seems that the adhesive that fastens the needle to the coil has failed and the needle is decoupled from the actual gauge. I'll need to work on that at some point but installation will require pulling most of the dash trim and the cluster out.

[beat_truck]

Originally Posted by MadMan

https://www.allpar.com/mopar/lean-burn.html

The short version is that the guys at Chrysler discovered that if they had super precise control over the ignition timing, they could run the carb super lean and still achieve the same performance as a richer mixture with a regular old fashioned vacuum advance distributor. Yes, it was motivated by meeting emissions standards, but in theory that sounds plenty better than the 'old way' and it should improve fuel economy and keep the same performance.

It was a simple system, but not as simple as you might think.

The system measured:
1. Engine speed (r.p.m.).
2. Engine load. [likely the MAP vacuum]
3. Throttle position.
4. Speed of throttle movement.
5. Air temperature entering the engine.
6. Engine coolant temperature.
7. Carburetor throttle open or closed.
8. Engine starting.

As for the old fashioned carburetor and ignition system being 'better' - that sounds entirely typical of all the grumbly old farts in the repair industry. It's not that anything is 'better' it's that they are used to something being a particular way. They all said the same things about fuel injection, front wheel drive, unibody, disc brakes, MacPherson struts, I could go on and on. I'm sure that 'many people' also thought that hand cranking your engine was 'better' than having a starter, and that acetylene lamps were better than those new-fangled electric lights. lol You could probably go even further back and some guy would've said that steam was better than internal combustion.

The v8s might have had all of those sensors, but most slant sixes did not. It seems that only the very last couple years did. My '83 didn't have most of them. As I said, it had the Lean Burn box on the air cleaner, but it had a normal 1bbl carb with no sensors attached. And no, the truck hadn't been altered. It matched up exactly with the emissions tag on the inner fender and the rebuild kit that I bought for the carb, and no wires were cut up.

Like I said, that system might have looked good on paper, but like most of those abortions that were created as a stop gap between regular carbs and fuel injection, they didn't work well in reality. Especially as they aged.

I was eventually going to ditch the Lean Burn setup for a regular vacuum advance distributor, but I sold the truck after hitting a deer with it.

[MadMan]

Originally Posted by beat_truck

The v8s might have had all of those sensors, but most slant sixes did not. It seems that only the very last couple years did.

I mean, I don't have much experience with them, but they kind of need 'all' of those sensors to work. By modern standards, it was very rudimentary, didn't control the carb in any way.

[MIPS]

Aaaand we got oil pressure again.




So it seems that for some reason an 80psi pressure sender is not a common part anymore. The Borg Warner catalog only lists a sender rated for 100PSI for the Eagle and pretty much every other car made by AMC, Jeep and International Harvester going back to the 60's. TSM doesn't specify anything either. It also doesn't list the scale resistance and at the same time I've never seen a factory oil pressure gauge on any car for that matter that was scaled for 100psi. Only the aftermarket stuff.
Anyways, lets assume that the variance in range resistance between the 80 and the 100 is about 12%, so with a reading of 63psi I should be seeing around 50psi which for a hot idle should be excellent and if I compare to other people on the internet, should be fine for quick visual indication and MILES above all these randos seeing stuff like 13psi at idle.

[MadMan]

I wonder if you could just put a resistor in series to adjust the reading. Might want to get an oil pressure gauge (like, you know, a hydraulic gauge) to get an accurate reading for a baseline. But hey, it is working now.

Also, are you sure a 100psi sender would not be used for the 80psi gauge? Could just be the maximum pressure rating, not necessarily its usual top end.

[MIPS]

I'm driving down the highway going 100 and my needle just sits at 75psi. I mean in this application that should be fine but I straight up don't believe my bearings are in that perfect of shape.
I actually can't really find a spec for the gauge or the sender. If it drives me crazy enough I'll, have to dig out the dial-an-ohm, find the upper and lower limits on the gauge and start seeing what other 80psi senders have the same range.

[Eric H]

As long as it's accurate at Zero you're fine.

[MIPS]

Oh here was an interesting failure.
I took a pothole on the highway and the engine went totally dead. Couldn't restart it. I had to call to get some tools brought in and found out I lost my TACH. After a bit of investigating I determined while still on the side of the highway that it vanished after leaving the ignition module.



If you don't know what this is, these are great. I might of mentioned it before.
So points-type ignitions suck and require a TON of maintenance and I'm sure anyone old enough to know points will tell you how much it sucked. the Duraspark system however replaces points with a hall effect pickup in the distributor and electronic amplification system that generates the TACH instead. It's all solid state and requires no maintenance.
Anyways, you can potentially forget it's in there from how little you will need to touch it and mine has been in there so long the connectors have become brittle. One such socket had split repeatedly and the electrical connections had pulled themselves out through the back of the connector.



Note the green wire in that harness. That's TACH. The bump must of slipped it out and that was my issue, so a ziptie and pushing the pins back into the plug and I was off and running again.

Okay, so if the module has bunk connectors, why not just replace the module?
So, Duraspark and Duraspark II came in a number of variants for different types of vehicles. They were normally identified by the number of connectors they had, plus the color of the grommet. An AMC Eagle uses a module with three connectors (distributor pickup, harness wiring and computer electronic retard) and a yellow grommet. Most people sell a version with only two connectors and a blue grommet. Even other eagles I've salvaged from did not have their original module because if you do the Nutter Bypass you don't need the OEM unit, therefore a blue grommet version was cheap and easy to get.
While you can get replacement plugs on the harness side, the sockets on the module side seemingly are not sold separately, so I'm waiting for a chance to get a beat module with good sockets I can steal and splice those on. No point replacing a module that isn't defective.

[MadMan]

lol most old mechanics piss and moan about electronic ignition in much the same way as they do about LeanBurn and anything else computery. I guess they'd rather clean their points every 100 miles. MUCH easier.

https://www.rockauto.com/en/catalog/...ule+(icm),7172
Here you go, yellow grommet on the 6H1016. Likely both are the same. Interestingly it's only for 1982. I wonder if they only did the electronic carb in 82 or something. Or rockauto's listings could be wrong, wouldn't be the first time.

Also I love the AMC sticker on the Motorcraft-branded box lol. Nothing to see here, folks!

[Eric H]

Old Mechanic here, Points usually didn't abruptly leave you stranded miles from anywhere, Electronic Ignition did that twice to me. One was a GM HEI that I had retrofitted into my 68 Nova 6 cyl, the other was an 87 Toyota Pickup, died on the 10 Freeway in heavy traffic while passing.
I used to see a lot of those Ford modules fail back in the 80's, the 90's distributor mounted modules also had a horribly high failure rate. I wouldn't go anywhere with an early Electronic system unless I had a spare module and the tools to change it.

Newer systems are much more robust and redundant, one driver per coil on the newest systems with individual coils, of course the Crank Sensor could fail, but that seems to be a very rare event.

[mr_rye89]

I didn't know AMC used Duraspark. Just Everyone Else's Parts lol.

I killed the ignition module on my '79 Toyota, Good luck finding another one for sane money. It got replaced with an MSD Streetfire box, which works great for about 5000 miles before it won't let you rev past 1500. Replaced that with the Autozone $20 HEI module mounted on a heatsink AWAY from the engine. Still worked when I sold it.

I also had the Briggs Twin I/C in my lawn tractor running an HEI module. Using an ABS sensor off a Ford pumpkin, HEI module, GM dual tower coil pulled from a W body. Works good but disables all the safety switches.

[MadMan]

Originally Posted by Eric H

Old Mechanic here, Points usually didn't abruptly leave you stranded miles from anywhere, Electronic Ignition did that twice to me. One was a GM HEI that I had retrofitted into my 68 Nova 6 cyl, the other was an 87 Toyota Pickup, died on the 10 Freeway in heavy traffic while passing.
I used to see a lot of those Ford modules fail back in the 80's, the 90's distributor mounted modules also had a horribly high failure rate. I wouldn't go anywhere with an early Electronic system unless I had a spare module and the tools to change it.

Newer systems are much more robust and redundant, one driver per coil on the newest systems with individual coils, of course the Crank Sensor could fail, but that seems to be a very rare event.

I love how you swooped in an proved my point. Another reason newer systems are more robust is simply down to delicate electronics being very old technology now. It's very well-understood and failure points have been learned by now. Manufacturing defects have been ironed out. High quality parts are widely available and cheap now. Etc, etc.

[MIPS]

It's still neat to hear from the other side. I already knew that equivalent systems are still not permitted in most aircraft due to the fact that points will gradually fail while an electronic ignition will instantly fail. Personally myself I've yet to seen one fail (mind you, I'm currently using my only one) so sometimes experience counts.

[beat_truck]

Originally Posted by Eric H

Old Mechanic here, Points usually didn't abruptly leave you stranded miles from anywhere, Electronic Ignition did that twice to me. One was a GM HEI that I had retrofitted into my 68 Nova 6 cyl, the other was an 87 Toyota Pickup, died on the 10 Freeway in heavy traffic while passing.
I used to see a lot of those Ford modules fail back in the 80's, the 90's distributor mounted modules also had a horribly high failure rate. I wouldn't go anywhere with an early Electronic system unless I had a spare module and the tools to change it.

Newer systems are much more robust and redundant, one driver per coil on the newest systems with individual coils, of course the Crank Sensor could fail, but that seems to be a very rare event.

My last Ford, an '88 4 banger Mustang, left me stranded when the TFI module on the distributor took a dump. Between that, rust, and several other problems it had, I sent it to the boneyard.

I think the ignition module was on it's last legs in my '91 Ranger when it went to the boneyard due to rust. It was one that was a 4 banger but had 8 spark plugs. Sometimes the tach would start reading half the RPMs it was actually turning. I never checked, but I suspect half of the plugs quit firing at the same time. Shutting the ignition off and turning it back on always caused it to go back to normal.

The only other ignition failure I've had was a coil pack on a POS VW Jetta. That whole car was one giant failure, though.

I would never even consider trading modern electronic ignition for points, though.