Be back in an hour....
New to me 78 NYB on its way but please Don't tell my wife
- Thread starter 73 T&C
- Start date
Swapped the gasket. Still missing but much improved. Putting the engine on the analyzer tomorrow.
Off like a tupee in a windstorm to a cocktail with the family..... pre-graduation event for parents during prom. Yuck!!! Rather be working on the car.
Off like a tupee in a windstorm to a cocktail with the family..... pre-graduation event for parents during prom. Yuck!!! Rather be working on the car.
Here’s the old gasket.
Good night..... more tomorrow.
Good night..... more tomorrow.
Wow! I drove the kids out to their @after party at 1:30 AM and proceeded to stay up until they got home safe. This parenting **** sucks.
On the way to auto parts store for some minor supplies on my way to the shop....
Y A W N!!!!!!
Smack, smack , smack.
On the way to auto parts store for some minor supplies on my way to the shop....
Y A W N!!!!!!
Smack, smack , smack.
Carmine
Old Man with a Hat
Are you confident you're hitting the base of the carb and not the carb body (and it's gasket)? Let's see a photo of that gasket when you remove it. I'd like to see the defect that would allow that leak.
Carmine
Old Man with a Hat
What the hell? Your later posts didn't load when I wrote that, only after I posted! Well great minds and all that.
All hooked up....
kv test:
Wave pattern:
kv test:
Wave pattern:
Here you go Carmine:
Old gasket from both sides.
bottom shows a decent bite into the gasket.
Top only shows bite on back
Old gasket from both sides.
Top only shows bite on back
Lots done today....
Checked the cap and rotor... cleaned them up inside although not really all that dirty.
Checked the pickup coil and it is within specs and almost 300 ohms (between 150 and 900 ok)
Finally dialed in the carb per FSM. Only things off were choke pull off being too far back. Little bit of very careful crowbar pushes brought it back and I also adjusted the link. Secondary air valve needed a touch more closing spring. It also needed to be set to max open to 1/2”..... it was opening a bit too far. Choke link was a little tight and binding. Little to do there but it’s working smoothly now. Set the mixture to 4-1/2 and 4-3/4 as smoothest idle (drivers right and left respectively).
Secondaries now opening correctly, transitioning smoothly with no bog at all.
And....I’m finally getting “that sound” as it downshifts and gets into whatever sweet spot of the horsepower that was left by 1978.... WahWahhhhhhh...as it’s supposed to do.
I didn’t brake it to load up the torque converter to build up revs to check for Stan’s Bog.... because... why? I did floor it from low rpm rolling start with no bog but not much power either. You need RPM to get power with the secondaries.... but no bog is very good.
Tranny up shifts fast. Much faster than my wagon and I don’t see any adjustment. Will need to look into that. A touch easier downshift and gearholding to highr RPM would make it a bit more responsive to drive in the city. But this is really a torque engine meant to pull at low RPMs...... but not that low.
Electronic Lean Burn
Checked the timing again through acceleration. Timing drops about 8 degrees immediately upon moving the throttle back off it’s rest and breaking the throttle circuit. It jumped almost right back as soon as throttle movement actuated the transducer. Adjusted the transducer with the timing as per the 77 FSM ELB spec. End result was a 1-2 turn out which minimized the lag between breaking the switch contact and the timing returning.
Stan is correct, there is indeed a delay in an internal Processing that occurs right at the worst part of the transition from idle to acceleration which is a point of a drop in vacuum at low RPM.... on a mechanical system, the drop in timing is not as instantaneous. Likewise, at low rpm, opening the throttle from almost closed at idle really plays havoc with air flow until the air (which has mass) is accelerated in to fill the vacuum. Springs and diaphragms take time to move....
I’m working through that particular puzzle in my head now. My feeling is that the delay, because of the volumes we’re talking about is actually too short. Probably not a problem on a smaller engine with a smaller two barrel where the idle transition is less severe.... that’s my own theory...
Let’s all remember, that the point of the ELB was for engine management and emissions control. Also...this was done without a catalytic originally. So the timing, once dropped, takes time to come back full on to reduce NoX and CO..... just like the old OSAC valves would hold back the vacuum advance. But unlike the old mechanical restriction, you can’t just bypass it.
The system also has a kind of drive by wire feel to the throttle response. This is particularly noticeable at low speed and rpms. Slight movements of the throttle feel cold blooded. More throttle returns to the level of responsiveness and power I’m used to in my 73.
More fiddling.
Took the car out a few times after all the testing on the machine.... to get the idle to above setting and about 750 rpm with a/c on and in gear/ 850 in neutral without A/C. I found a low kV reading on #8 but it turned out to be a mis-seated boot on the plug. Scorched my upper arm a bit getting it though.
Once all set... time for a good road test.
the secondaries kicking in. (Toward the end and you’ll have to listen closely)... it is a luxury car after all!
Fixed some of the marker lights before going home.
Next weekend.. I’ll clean them out and polish the lenses.
Otherwise... Pleased with the overall result.
Checked the cap and rotor... cleaned them up inside although not really all that dirty.
Checked the pickup coil and it is within specs and almost 300 ohms (between 150 and 900 ok)
Finally dialed in the carb per FSM. Only things off were choke pull off being too far back. Little bit of very careful crowbar pushes brought it back and I also adjusted the link. Secondary air valve needed a touch more closing spring. It also needed to be set to max open to 1/2”..... it was opening a bit too far. Choke link was a little tight and binding. Little to do there but it’s working smoothly now. Set the mixture to 4-1/2 and 4-3/4 as smoothest idle (drivers right and left respectively).
Secondaries now opening correctly, transitioning smoothly with no bog at all.
And....I’m finally getting “that sound” as it downshifts and gets into whatever sweet spot of the horsepower that was left by 1978.... WahWahhhhhhh...as it’s supposed to do.
I didn’t brake it to load up the torque converter to build up revs to check for Stan’s Bog.... because... why? I did floor it from low rpm rolling start with no bog but not much power either. You need RPM to get power with the secondaries.... but no bog is very good.
Tranny up shifts fast. Much faster than my wagon and I don’t see any adjustment. Will need to look into that. A touch easier downshift and gearholding to highr RPM would make it a bit more responsive to drive in the city. But this is really a torque engine meant to pull at low RPMs...... but not that low.
Electronic Lean Burn
Checked the timing again through acceleration. Timing drops about 8 degrees immediately upon moving the throttle back off it’s rest and breaking the throttle circuit. It jumped almost right back as soon as throttle movement actuated the transducer. Adjusted the transducer with the timing as per the 77 FSM ELB spec. End result was a 1-2 turn out which minimized the lag between breaking the switch contact and the timing returning.
Stan is correct, there is indeed a delay in an internal Processing that occurs right at the worst part of the transition from idle to acceleration which is a point of a drop in vacuum at low RPM.... on a mechanical system, the drop in timing is not as instantaneous. Likewise, at low rpm, opening the throttle from almost closed at idle really plays havoc with air flow until the air (which has mass) is accelerated in to fill the vacuum. Springs and diaphragms take time to move....
I’m working through that particular puzzle in my head now. My feeling is that the delay, because of the volumes we’re talking about is actually too short. Probably not a problem on a smaller engine with a smaller two barrel where the idle transition is less severe.... that’s my own theory...
Let’s all remember, that the point of the ELB was for engine management and emissions control. Also...this was done without a catalytic originally. So the timing, once dropped, takes time to come back full on to reduce NoX and CO..... just like the old OSAC valves would hold back the vacuum advance. But unlike the old mechanical restriction, you can’t just bypass it.
The system also has a kind of drive by wire feel to the throttle response. This is particularly noticeable at low speed and rpms. Slight movements of the throttle feel cold blooded. More throttle returns to the level of responsiveness and power I’m used to in my 73.
More fiddling.
Took the car out a few times after all the testing on the machine.... to get the idle to above setting and about 750 rpm with a/c on and in gear/ 850 in neutral without A/C. I found a low kV reading on #8 but it turned out to be a mis-seated boot on the plug. Scorched my upper arm a bit getting it though.
Once all set... time for a good road test.
the secondaries kicking in. (Toward the end and you’ll have to listen closely)... it is a luxury car after all!
Fixed some of the marker lights before going home.
Next weekend.. I’ll clean them out and polish the lenses.
Otherwise... Pleased with the overall result.
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78Brougham
"Chump"
Just out of curiosity, did the TP transducer check out, as far as no flat spots when you tested it?
Maybe if it had a flat spot it could give you that delay?
Maybe if it had a flat spot it could give you that delay?
Yes.... TP has a natural flat spot at its zero position. The FSM calls for setting it and then turning it 1/2 turn in before locking it down. The TP is a magnetized coil with a movable iron core that is wired to the throttle. By moving the core you actually affect the voltage that is creating the magnet and thus an electrical signal. Setting it at its zero point (mass of core toward the center of the coil) puts it at its maximum potential for change and thus creating the clearest and largest signal as to both speed and position of the throttle. Google Transducer.
I believe this is to allow the computer to drop the timing when opening the throttle (and thus opening the idle switch ) to avoid ping/backfire/stall of the engine due to the momentary super lean slug of air created at initial throttle movement.
The TP then takes over as to position of that open throttle and also begins to raise the advance a little at a time while the carb is in the off idle position (idle switch is open)
From observation, the rate of opening either holds the increase in advance off or slows the increase rate after the initial drop and return.
In 78, they removed the mechanical advance which is normally good for about 10 degrees of advance. So setting the base timing is critical. As it sets the minimum advance as an absolute. To that minimum advance (in this case 14 degrees BTDC) the computer adds varying amounts of advance depending on sensor input. If the engine is cold for example, it will add 10 or so degrees while at the same time disabling the vacuum sensor. And, for the first 90 seconds, on a cold engine, it will add another 10 or so degrees. Carb is also enriched for that initial time frame via a vacuum signal to the carb that is controlled by temperature.
It’s the transition in temperature that freaks the system out and is the most annoying as to drivability.
It’s an interesting system and idea.
I believe this is to allow the computer to drop the timing when opening the throttle (and thus opening the idle switch ) to avoid ping/backfire/stall of the engine due to the momentary super lean slug of air created at initial throttle movement.
The TP then takes over as to position of that open throttle and also begins to raise the advance a little at a time while the carb is in the off idle position (idle switch is open)
From observation, the rate of opening either holds the increase in advance off or slows the increase rate after the initial drop and return.
In 78, they removed the mechanical advance which is normally good for about 10 degrees of advance. So setting the base timing is critical. As it sets the minimum advance as an absolute. To that minimum advance (in this case 14 degrees BTDC) the computer adds varying amounts of advance depending on sensor input. If the engine is cold for example, it will add 10 or so degrees while at the same time disabling the vacuum sensor. And, for the first 90 seconds, on a cold engine, it will add another 10 or so degrees. Carb is also enriched for that initial time frame via a vacuum signal to the carb that is controlled by temperature.
It’s the transition in temperature that freaks the system out and is the most annoying as to drivability.
It’s an interesting system and idea.
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MarPar
Meat Man with a Hat
So Javier, if I am reading it right, the throttle is like a potentiometer?
Yes and no Mario.
A potentiometer just measures relative absolute position via a varying voltage signal based on a resistance. The TP transducer also measures the speed of that movement change by creating a greater amplitude of the signal relative to velocity (as much as 2v).
For example, a generator creates energy through the relative velocity of movement of an iron core through a magnetic field (in the generator it is also wound but in the case of the TP transducer it isn’t). The field is created by the coil surround nding the movable iron core attached to the throttle. It will send a signal which will hold the temporary retarding of the advance based on this signal. The faster the movement the greater the signal.... turning relative velocity into a signal that can be read and responded to.
Testing involves checked for continuity through the two points of connection at the base of the transducer and then taking the TP transducer off and moving the sensor in and out quickly to observe measured change in voltage across the outer coil and the resultant change in timing to confirm operation (it should drop part of the advance out). The one in this car is working correctly as per the above test.
It’s final (or temporary) rest point off idle also creates a position signal that is read just like a potentiometer.... but not exactly.
Great question and one that made me scratch my head quite a bit as I figured it out.
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MarPar
Meat Man with a Hat
Thank you for the explanation. 
Heady stuff for the 70's
Heady stuff for the 70's
Thank you for the explanation.
Heady stuff for the 70's
OMG yes!!!!
Came out of Chrysler’s Huntsville group working on the Apollo program at the time (from what I’ve been able to read)..... which was making control systems and hardware for NASA. Specifically, they worked on control systems on the command module..... bleeding edge at the time indeed.
Hence the tag line at the time and just before “ Extra care in engineering... and it shows” although they really didn’t play it up as much as they should have iMO.
The problem, just like other cutting edge stuff, is one of support and understanding through a large and diverse network.
The early open system ( no feedback from O2 sensor) only lasted about 4-1/2 years and has two versions of the same hardware which are not at all interchangeable. So it’s a bit orphaned with most service parts NLA
For quite some time.
Likewise, it is also close to impossible to tune for better and more aggressive performance. First step is getting it dialed in to operate satisfactorily and that is what I’m trying to close in on.
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Dear all....
Sorry for the nerdapalooza of late.... but this is really what makes me interested in this primitive control system.... and getting it back up and running correctly may be the first step in just ditching the whole GDF thing!!!!!
Lol!!!
Sorry for the nerdapalooza of late.... but this is really what makes me interested in this primitive control system.... and getting it back up and running correctly may be the first step in just ditching the whole GDF thing!!!!!
Lol!!!
Interesting item about the lockup torque converter.
It explains a lot of what I’m talking about.
“Long-time mechanic and tuner Hemi Andersen wrote that “The original lockup speeds were too low, which caused the engine to labor and bog down. Chrysler sent out a modification kit, with a new lockup valve and heavier spring, as a free warranty repair. To install it, one had to take the valve body from the transmission. It locked up the torque converter at around 42 mph, rather than at 27 mph. (In 1988, a Chrysler tech manualspecified lockup and disengagement speeds as being around 24-50 mph, depending on the engineand axle; so, when accelerating lightly, the transmission could shift to third, stay there for a time, then engage the lockup clutch.)”
Came off Allpar site.
Mechanical override: Lockup torque converters
It explains a lot of what I’m talking about.
“Long-time mechanic and tuner Hemi Andersen wrote that “The original lockup speeds were too low, which caused the engine to labor and bog down. Chrysler sent out a modification kit, with a new lockup valve and heavier spring, as a free warranty repair. To install it, one had to take the valve body from the transmission. It locked up the torque converter at around 42 mph, rather than at 27 mph. (In 1988, a Chrysler tech manualspecified lockup and disengagement speeds as being around 24-50 mph, depending on the engineand axle; so, when accelerating lightly, the transmission could shift to third, stay there for a time, then engage the lockup clutch.)”
Came off Allpar site.
Mechanical override: Lockup torque converters
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Went by shop on my way back from lunch to return wrench I accidentally pocketed... and to check on the NYB for cold start up.
Choke stuck open. No start until it was freed. Cheap after-market crap. Just bought the correct Carter unit. Should be in in two days.
Will bend rod a bit to see if I can get it from going over center and sticking after full warmup. Hadn’t driven it to this extent till now.
Choke stuck open. No start until it was freed. Cheap after-market crap. Just bought the correct Carter unit. Should be in in two days.
Will bend rod a bit to see if I can get it from going over center and sticking after full warmup. Hadn’t driven it to this extent till now.
78Brougham
"Chump"
What if you put a dizzy in with a mechanical advance, or fitted a mechanical advance into yours, but no vacuum advance for obvious reasons.
Would that help the stumble? Kind of a hybrid system.... combining two systems. Old and older LOL.
Would that help the stumble? Kind of a hybrid system.... combining two systems. Old and older LOL.
Interesting idea. But if I go to all that trouble I may as well pull out the whole thing and go with a pre 76 system
I’m thinking that I just need to keep the advance up for a 1/4 second as the throttles are breaking off their rest point.
Thinking about ways to do that...
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