Captain Obvious

Congrats! That can't be the original interior, can it? [ATTACH=CONFIG]59457[/ATTACH] Please tell me all the upholstery has been redone!

Yeah, pulling the heater core is no treat. I took my whole heater box out when I had the dashboard out of the car for other reasons, and getting to the heater core then is obviously cake. I took some pics of my box when I had mine completely apart, and I would be hard pressed to believe that the air blasting straight down on the bottom of the shell would split evenly as well. So, all that said, you've certainly got nothing to lose by flushing the heater core. I've got no other bright ideas. How hot is the hot side? The greater the contrast between the two sides, the harder it is to explain any of this. Another question... What do the defrost outlets do when you put it into defrost mode? Is one of them cold as well?

I'm no expert on the HVAC system, but I was deep into mine and I can't come up with any possible explanation for what you're seeing. As for your heater core theory... remember that the coolant runs from one side to the other, not between front and back. With that in mind, a partially clogged core does not support what you think you're seeing. If there were come clogged rods, it might be a little warmer in the front of the core when compared to the back, but not a differential between left and right. If you are truly getting cold air out of one floor vent while getting hot out of the other, then I'm stumped.

My first thought was AAR as well. I'm thinking that maybe it's gunked with sticky PCV system blowby and it still works, but it sticks in place. Theory being that the AAR is supposed to creep open as the engine cools off and by the time you start the cold engine next day, it has creeped open enough to cause a high "cold" idle. If the AAR is sticky, maybe it's not opening like it should, but the vibration and shock of starting the motor is enough to get it to move to the correct position? Then after the second start attempt, it will be OK. So the question would be... Once you have feathered the gas pedal for a few seconds, does the idle continue to struggle, or is it a nice smooth high idle like it's supposed to be? My second thought would be that you are always borderline lean and when the engine is stone cold it just can't handle it.

Thanks again guys. The car in question is a 77, and I'm pretty sure that I remember they were the self tapping variety. I've got the other two screws (the machine screw style) and I remember thinking to myself that it seemed really stupid (and expensive) for Datsun to have used three different styles of screws to hold that clamshell in place. I think I'm going to unscrew one or two of my door sill screws and see if I can't figure out if that's what happened. Thanks for the saucer pic Blue. I knew it...

And BTW, that's an awesome pic with your annotations on it. Very helpful!

Thanks much Mike. Now I've got some kind of idea what it is that I'm looking for. I was cleaning up a little in the workshop this afternoon (oh, the horror), and found a plastic baggie with seven screws. Thought I might be on to something, but there were too many of them, they were black plated, and a little too long. So they aren't the right ones, but they were important enough for me to put them in a baggie. Now if I could just remember what THEY were for. OK... Here's an idea. What do the screws that hold the aluminum dooe sill plates on look like? Maybe I got all the hardware, but in the wrong locations? Are the ones that hold the door sill plates flat heads, or pan heads? Are they supposed to be black plated? Darn aliens... Came down from Canada to escape the winter cold.

Thanks guys. I've been all over the shop looking for my clamshell screws. I think aliens took them. It bugs the crap out of me because I know how easy stuff like that is to misplace, so I'm pretty careful. I've got the other two machine screws in a little zip-top baggie just like they are supposed to be, but the other four longer ones are not with them. That's what makes this even more difficult... I know where they're SUPPOSED to be, and they're not there. Mike, If you get a chance to take a pic, I'd be much obliged. I'm not in any hurry so don't risk frostbite for the pics, but when you get a chance. Haha! I really don't want to have to hog those things out with a bench grinder! I've found people on ebay selling clamshells, but it seems really stupid to buy a whole clamshell just for the four screws. And beyond that, it's unclear if the screws are even included...

I took my steering wheel clamshell trim off a while ago, and now I can't find the four screws that hold the two halves of the clamshell together. The stupidest part is that I have the two machine screws that hold the lower clam to the underside of the ignition switch and steering column, but the four that hold the two plastic parts together are MIA. :mad: I've got a container of assorted Z hardware and might have something in there that might work, but I've tried a few and I'm worried about stripping out the weak plastic threads with too much trial and error. Anyone have a picture of the four screws in question so I at least know what I'm hunting for? Are the threads more like a machine screw, or a wood screw?

Haha!! I remember a really funny pic entitled "Beauty and It's Ugly Bitch" or something like that... I've got a copy of it here, but it's most certainly inappropriate. I'm sure there are others on this forum who remember that pic!

Don't get me wrong... My snake oil detector has a hair trigger, and I'm not calling snake oil on this one yet. I can't tell you why it wouldn't work. Haha! Of course, I can't tell you why it SHOULD work either, but that's the point. The best strike I can come up with AGAINST the concept is the lack of expert consensus and the slow adoption in the market. Theory being that when something really, truly, really proves itself to be a better mouse trap, then the hype factor kicks in and market adoption is strong and rapid. That has not happened in this case. Best strike I can come up with FOR it is that fact that the concept has been around for so long and nobody has been able to refute the claims. The "where there's smoke there's fire" defense.

I'm with you Mike. I find the claims and the theory intriguing. Enough so that I built a desulfator a few years ago to try to resurrect my "not yet internally shorted, but low capacity" cycle battery. I charged the battery to what it would accept. measured the capacity, alternated hanging my desulator on it for a few days and recharging, and then measured the capacity again. In the end, there was no capacity increase and I had to replace the battery. But... Before you go and throw in the towel on the technology, there are plenty of potential reasons why it did not work for me. Reasons ranging from the battery may have been too far gone to save, to I made some of my own theorized design improvements to the traditional desulfator design. :bulb: Haven't thought about it since, but it's still sitting in the corner of the workshop! Thanks for the reminder!

What is supposed to happen is that there simply isn't enough travel in the adjuster mechanism to "catch" a tooth on the adjuster star wheel. As you saw when someone else was pulling the handle, there is a small lever that catches on and turns the adjuster gear. But the arm is only able to turn the gear if it catches a tooth. When the brakes are fully adjusted, there is supposed to be such a small amount of travel in that arm that it never "retreats" far enough to get behind the next tooth. It goes like this... As the shoes wear, the shoe travel increases, and as the shoe travel increases so does the travel in the adjuster arm. The magic occurs when the arm travel is so great that it clicks behind a fresh tooth on the gear and when the lever is pulled the next time, it advances the gear by one tooth. In other words... What your are describing should not be able to happen. Not saying that it isn't... Just saying that it "should be" impossible.

That's great. Did you actually check that there is fuel getting into the bowl? You did the bench set-up, but you didn't verify that it worked. Sure you might have a faulty ballast resistor in addition to other problems, but a faulty ballast resistor isn't temporarily fixed by a blast of starter fluid. Start simple... Pull the hose off between the bowl and the nozzle and use a clear tube to measure the bowl level as described in the manual.

Just because you are getting fuel in the lines that lead to the carbs doesn't mean you are getting fuel INTO the carbs. Before it actually gets into the float bowl in order for the engine to use it, the fuel has to get through the screen filters and past the float valve. You might have something wrong with the filters, a stuck float valve, or a badly mis-adjusted float. I'm making a distinction between TO the carbs and INTO the carbs.

Mike, Your suggestion about simulating the forces of operation is what I had planned to do when I pull the throttle body. I believe you and I are thinking the same thing... That maybe the throttle shaft bushings are worn in some weird way such that the vacuum pulling the throttle plate and shaft towards the engine or the return spring is causing something to bind at times? Zed Head, About that pressure imbalance on the edges of the throttle plate... I was thinking of that too, but I don't know enough to be sure - Does that really happen? If so, it seems like it would plague just about every butterfly valve device out there. I'll double check for crud when I pull it too. I did check for cleanliness while on the car, but you can obviously do a more thorough job off the car. As for the A/C idle up stuff, I had the linkage disconnected right at the throttle body. There was no linkage connected to the throttle shaft at all, and it was still sticky. I can state with 110% certainty that it has nothing to do with any part of the linkage. Guaranteed. So anyone coming up with any theories that could account for the seeming temperature dependence? Thanks for the help guys!!

Well you know the history of this car with the blasting grit and all. My first thought was a return of something related to that. The confusing detail is that the throttle shaft always feels perfectly smooth and free moving when the engine is off. It's only sticky when the engine is running? What causes that??:paranoid: I guess I'm gonna have to pull the throttle body and look at it on the bench.

Thanks for the suggestion, and no, I have not disconnected the BCDD. I know the BCDD is often the cause of what people call a hanging throttle, but in my case, I can't see how it could be related. My problem isn't the BCDD path around the throttle plate... It's the throttle plate itself is not returning to it's stop. There's no mechanical connection between the active parts of the BCDD and the throttle butterfly.

Sometimes when I come to a stop, my idle hangs up and will not return to the correct RPM. Just started like two weeks ago. I know it's got nothing to do with the linkage or the dashpot, because I removed both of them and it was still sticky. I also know that it's not sticky goop inside the throttle body. It's clean. It's not sticky all the time, but when it gets that way, I can feel that the throttle shaft is a little more difficult to turn than "normal". Due to the fact that this is a recent development (now that it has gotten colder), my first thought was that maybe my throttle body was icing up. But heres the thing... I can shut the engine off while the throttle is stuck open a little, and as the engine cranks to a halt, the throttle plate closes just like it should, and moves freely. In other words, the instant the engine stops, it will move free and easy and "clank" hard against it's screw stop just like it should. Two seconds later I can start the motor, and it's fine for a minute or two, and then it gets sticky again. Doesn't seem like ice to me... It's not sticky goop. It's not grit in the bearings. It's not the linkage. It's not the dashpot Anyone have any ideas?

This illustrates perfectly what I meant by it being a second order phenomenon. You aren't controlling vacuum with the mixture, you are controlling idle speed. It's the idle speed that's affecting the vacuum, not the mixture. Vacuum at idle is not an indicator of fuel/air mixture. Peak idle RPM at a constant throttle position is an indicator of mixture. I'm sure we're saying the same thing.

Pics or it never happened.

Haha! Did not. Despite the distain for all things AMC, if it made it this far in that condition, then I think it deserves some applause. I'd rather have a Hornet, but that's just me.

It all seems pretty normal to me... Eight turns down for you = sooty plugs, and smells very rich, good performance? - That's because you are very rich. Three turns down for you = clean plugs, smells normal, good performance? - That's because you have leaned out the mixture to closer to the correct mixture What's the problem? As for highest vacuum at idle, the knobs adjust mixture, not vacuum. I'm no expert, but I'm having a real hard time caring about what the vacuum gauge says when you're messing with the mixture knobs. Any change in vacuum when messing with the knobs is a second order effect caused by a shift in idle RPM. There's no primary link between manifold vacuum and nozzle drop.

Now that's just wrong. Funny, but wrong. :laugh:

Thanks for the details. Wow... That's some beautiful stuff there.