Captain Obvious

I did not pour over the 75 wiring diagram, but for other years, a temperature switch controlled things like ignition timing and EGR engagement. I understand that you're not running the original ignition module, but maybe somehow you're getting EGR pumped into the intake manifold when you shouldn't be? Just tossing out ideas.

Daluvian, I will look to see if I've got one of those.

I have seen that the early ignition switches were different. Mechanically at least. The early switches used just one mounting screw to hold the switch to the back of the lock assembly, while the later switches used two mounting screws. And because of the mounting screw position(s), those two switches were not interchangeable. In other words, if you have an early ignition lock assy, you would not be able to go to Rock-Auto and simply buy an ignition switch for the back of it. R-A sells the new style switch and it won't fit the back of the old lock bodies. All that aside... The POINT is, I do know that the early switches are MECHANICALLY different than the later style, but I do not know if they are ELECTRICALLY different as well. And when I say "early", I'm not putting a hard date on that. I don't know when they changed over to the two mounting ear switch. I know I'm muddying the waters with a small point here (about whether the B/W wire has power on it when in START), but it might depend on the year and whether the switch has been replaced in the past. I suspect many of the ignition lock assys have worn out over the past and have been replaced with newer versions.

I've got some gland nuts here in a box. Can you post a pic of the style you're looking for? I'll check the box.

There was some discussion about such things a while ago, but I can't find the discussion. I remember that it happened because I created and posted this pic culled from the various wiring diagrams over the years: The wiring diagrams seem to indicate that starting in 73, that B/W wire is hot in both ON and START, but in 72 it is not? And I don't have reliable wiring diagrams for 70 or 71, so I can't tell if 72 is just an anomaly. It always seemed like a documentation error to me. Have you confirmed how it really works?

A local buddy of mine had a similar situation and his theory is crud in the gas tank. The crud gets sucked all to one spot as the car runs and eventually plugs the tube feeding the fuel pump. Shut the car off, vacuum stops, and crud settles back out. Car starts and runs again for a while. Another (simpler) suggestion is the valve on the gas cap isn't working correctly and you're drawing a vacuum on the tank. Maybe pop the cap next time the problem happens and see if there is a big woosh of air into the tank? That feeling of not being able to trust the car really sucks. All you want to do is enjoy it, and you can't stop worrying. Hope you get to the bottom of it!

I'm thinking that if you had more carbs, your engine might run longer? I mean, if you started out with ten or something.....

I run 10W-40 in my car. Why? Because back when these cars were new, 10W-40 reigned supreme. You could find 10W-30, but it wasn't nearly as prevalent as 10W-40. And you could find 20W-50 as well, but only at specialty "high performance" shops that used to have brick-n-mortar locations, but pretty much don't anymore.

Well I know very little about turbos and what's considered "normal", but I really don't like the stiffness of that turbo. Maybe it'll loosen up after the seals run-in, but I have no idea. Maybe some of the turbo guys can chime in and provide some guidance.

Well I'm no ME, but I have concerns about using two dissimilar parts for that assembly. It's really not a big deal and I'm not going to throw my body in front of anyone who wants to try it, but I've just got concerns. Things like this: If you make the tip out of some slippy plastic and press it into a tube... How deep of an engagement do you get? The whole thing is 5mm long. With the spring seat being maybe 3mm deep? So you get .078 inches of some slippy plastic into the end of a brass tube? You make the press fit mild and there's less force to hold it together. You make the press fit aggressive and that slippy plastic squeezes itself out of the hole just sitting static on the desk like toothpaste extruding out of the tube. Change the temperature and who knows what's gonna happen. And then you put that assy into an un-damped spring snapping application? When that thing changes position, what's the frequency of the bounce? That brass isn't going to change direction instantaneously. Newton's laws and all that say there will be forces trying to pull that thing apart. Like I said, not a big deal... A lot of discussion and analysis of such a small simple part.

Glad to (try to) help. I'm actually planning to be messing with floats later today. Call me.

The struggle is real: https://www.classiczcars.com/forums/topic/55190-float-level-advice-please/?&page=5#comments

So those carbs are the 72 three screw versions. They are supposed to have different needle valves in front and rear. Do you know what Ztherapy put in them?

Yeah, the original part was injection molded. That's what you do when your making hundreds of thousands of them. Or you're @SteveJ And I'm not sure what you meant about a brass tube with a plastic knob inserted... Are you suggesting the possibility of making the finished item out of two parts pressed together? If that's the case, I'd be wary of that. Remember, the bottom of the hole is the spring seat. And it's pressing in a direction to separate the two parts. Yes, in theory, all the force would be on the spring seat (and not on the thin wall tube around it), but there's the transition positions when the spring extends and all that inertia. I don't know how many G's that part sees when it snaps from one position to another, but I bet it's not trivial. Remember the same lubricity the plastic provides to the tip (to let it slide smooth across the switch contacts) will be allowing the two parts to come apart.

I'm no brake expert, but I would want a "stock-like" booster, not the tandem.

Could you put the stock intake snout back on and run the engine like that? In other words... Run the intake tract in NA mode and pull the turbo intake stuff off, but leave the turbo installed. I'm thinking that with the turbo in place you could look inside it while the engine is running to see if the impeller is spinning at all? I'm no turbo expert, but your description of how much force is required to spin it has me concerned.

And remember to take pics in 93 and 94 miles!

I would not consider either ABS or acrylic to be a good choice in the long term. Certainly usable for proof of concept and testing a procedure. Careful with the acrylic as it can be brittle and shatter if you push it too hard. Don't hurt yourself and wear eye protection! This could be done in a drill press, but it's really not the tool for the job. For the spring hole, you want the hole in the center and it probably has a flat bottom. The rounded tip is actually the easy part here... Just use a file while the part is spinning. Heck, since I don't consider it to be a high precision job, that's what I would do on the lathe. Use a file and eyeball the radius.

Got your message and sent one back.

Horn broke. Watch for finger.

I don't have any input into your fan issue, but just wanted to ask... Are you driving on the road when you took that pic, or sitting at idle somewhere? Reason I ask is, the oil pressure is low if you're out driving around. It would be OK for idle, but not for higher RPMs. Based on your posture on the road it looks like your RPMs should be higher than idle.

gotham22, If you want to send me a good part to use as a guide, I'll see if I can make a replacement? And no... I'm not going into the replacement headlight nubbin business unless someone presents me with a credible business case.

I'm not totally thrilled without the smoking gun, but let's hope the problem has been resolved and doesn't come back.

LOL!!

Sorry. My bad. Who am I to say something like that! Objection withdrawn!