Captain Obvious

IMHO, I think the two first steps would be to a) make sure the electrical connections to the EFI system are clean, tight, and making really good connection. Paying special attention to the temp sensor and the AFM, and b) simplify as much of the tubing as you can in order to minimize vacuum leaks. After you have simplified and gotten the basic system leak free and running well, you can start adding stuff back in. For example... For now, you can just cap off all the stuff running to the carbon can. You can also take off everything having to do with the AAR. The car will idle low until it warms up, but once it's warmed up, the AAR should be doing nothing anyway. I don't remember what they use the TVV stuff for... If it's EGR and EGR only, then you can cap all that stuff off too. Just trying to minimize all the tubing because each end of any tube is a potential vacuum leak. Make it leak free, get the basic system working, and then start putting stuff back on.

Here's some pics of the throttle body. You can see there are two small vacuum tube connection nipples on the bottom. The nipple on the left in the pic (points toward the radiator) should run to a "T" and from that T, it runs to both the carbon can and the distributor vacuum. The nipple on the right points downward towards the rear of the car is used for the EGR system (and only the EGR). So if you've removed the EGR stuff, you can cap that one off completely. Here's a closer-upper of the nipples. You want to use the one on the left and cap off the one on the right.:

The PCV hoses, while kludgy, are connected fine. The valve cover is correctly connected upstream of the throttle butterfly. Two things catch my eye quickly... First, your fusible links are in the wrong locations. You've got the large BLK link in the back position, and it should be in the front position. It won't explain the performance issues you're having, but fix them now before something goes wrong. They should look like this. The largest link should be the front outboard position: Second, I'm not liking the tube connected to the vacuum port on the bottom of the throttle body... There are two vacuum connections on the throttle body, one that points toward the front of the car, and one that points towards the rear. The one pointing forward is for the distributor vacuum (and carbon can). The one pointing to the rear is for the EGR system. What I'm not liking is there is a hose connected to the vacuum nipple that is pointing rearwards, but you've removed the EGR system. That nipple should be capped off with no tube attached. The hoes you have connected to it seems to wrap around underneath the throttle body, and my suspicion is that you're using it for distributor advance. Is that the case? And lastly... The temperature sensor is often the culprit in lots of EFI issues. Have you taken meter measurements to make sure it's working properly?

Haha!! The eyes burning is from your onion running so rich. Happens to lots of them. I'll head over to the other post and see what I can do.

Hmmm... With today's prices on the early cars, I'm having a hard time recommending any significant modifications from stock. How about you sell the early one and buy two later ones with the proceeds?

Agreed. Looks fantastic!

I'm assuming you're talking about the little three inch diameter boot that attaches to the transmission? If that's the case, then no... there is no retainer specified. Here's what I was told: https://www.classiczcars.com/forums/topic/44315-innermost-shifter-boot-any-clamps-holding-in-place/ However... I kinda like the idea of the zip-tie.

My general thoughts on the big picture is that it's your typical fuel injected Z that has been sitting for 30 years. Vacuum leaks (small ones all over the place) Dry-rotted leaky intake air ducting Corroded dirty connectors Questionable previous repair workmanship Fuel pressure problems TPS adjustment issues Ignition timing issues AFM that has been adjusted by a PO Maybe even some common issues like having the temp sensor and thermotime swapped Add to that, a list of aftermarket things that have been put into the car over the course of it's history: Injectors of unknown flow rate probably replaced at some point Aftermarket coil that may or may not need a ballast resistor Aftermarket ignition box that may or may not be wired correctly You know... The typical Z. Work on one layer at a time. Like an onion.

Quick look at the internets: Moog Parts defines "steering ratio" as the ratio of how far the steering wheel turns to how much the wheels turn. For example, if a 360-degree turn of the steering wheel causes a car's wheels to turn 20 degrees, then that car's steering ratio is 18:1 (360 divided by 20). So you cannot determine steering ratio simply by measuring the distance the rack moves for one revolution of the wheel. However, If everything else in the system is the same (like the lengths of all the other steering members), then the rack that moves more per wheel rev will have a higher ratio, but I'm not sure (in the Z car realm) that we have nailed all that down for sure.

Remember that just because you saw it on youtube* does not make it true. (Even if you saw more than one person suggesting that it was.) * or facebook, or twitter, or reddit, or parler, or etc

I would have to see the holes under that shiny new block-off plate to be positive, but I believe it is unnecessary to plug those two exhaust holes.* I think the block-off plate seals off the vacuum side of the intake manifold from both those two holes. If you want confirmation, take that plate off and post up a pic of the top-side of the intake manifold where that plate is bolted on. So that would be the good news. The bad news is I don't think that has anything to do with the problem you are having with the car. *other than keeping the mud daubers out of them.

I think the plan is sound. KYB's all around. Rubber bushings pretty much everywhere you can get them. I used poly on the front side of the T/C bars even though I could get rubber. Other than that, I put rubber wherever I could. That's what I have in my 77 and I love it. It's not a track car, but it just performs like it's "supposed to".

Honestly, I'm not sure. It appears that way, but the specs in the manuals are all kinds of screwed up. I dug into it a bunch in this "steering effort" thread: https://www.classiczcars.com/forums/topic/61176-steering-effort-differences-between-years/ but never completely confirmed most of the numbers. In that thread, we nailed down the lock-to-lock is different on the 240 vs. everything that came after (but just because the L-L is different does not guarantee that the ratio is different). We also nailed down that the 240 used a different pinion and rack gear than everything that came after (but just because the gear and rack are different part numbers, does not automatically require that the ratio is different). So, I would defer to rturbo.

Agreed. I guess now that you have moved the chamber edge back on E1 and I2, if I were you, I would do something similar to the rest of the valves, but making sure I didn't push it to the hairy edge and left a little material to guarantee that the head gasket ring didn't squeeze out past the material. Other than that, the only other thing I would do is make sure I broke the sharp edge where the new head planing surface meets the chamber. And I wouldn't even use power tools... Some fineish (400?) grit sandpaper ought to knock down any burrs and put a small radius on that edge. In other words... When they plane the head, they usually use a large cutter spinning in one direction. Because of that, it usually results in a burr (most prevalent on the downstream side of the cut). I would take some fine grit paper and work it around the chamber something like this to knock off any smeared burrs and/or make sure there aren't any sharp edges:

The bushing width on the 280 rack is wider than the 240. There are also other differences beyond that but I don't think they would affect form-fit-function. Stuff like details in the design of the inner tie rod ends. Different, but would be unnoticeable in application. But the only form-fit-function hurdle I can come up with quickly is the bushing issue.

I'm sorry, but you completely lost me with your description stuff above, but I will throw out some general notes that may be applicable. First, any material you remove from the chamber area in the head will reduce your compression ratio. You could gain that back in other ways, but not sure you were planning to do any of that. If you like the compression numbers where they are, you might not want to remove any more material than you really need to. Second, Not sure it matters, but I've measured a couple head gaskets, and I've found that the hole in the gasket is not round. Not sure it was an anomaly (or just a 280 thing), but they were oval-ish. Have you checked yours to see if it's oval or round? Third, when you're removing material from the head to bring the edge out to the fire ring, keep in mind that the metal band portion of the gasket will squeeze out into the chamber area a little as the gasket is compressed. If it were me, I would want the entire fire ring area to be supported on both sides by engine metal. In other words, I wouldn't want to ever have any portion of the fire ring hanging out unsupported (on either side) into the chamber area, and because of the extrusion that occurs on compression of the gasket, I would probably leave a small amount of extra material there to be sure that would not happen. I believe the gasket you have there is the one that was already compressed once? That may minimize that effect? I'm no engine builder expert, but those are my thoughts. Hopefully someone who actually knows what they're talking about comes in and provides better guidance.

LOL. Well there's your reward for tuning your mixtures in so well. It's certainly possible that there was a slight change in engine temp that aggravated an "already close to failing" piece of injector hose, but I suspect it's more just dumb luck with maybe a little bit of Murphy's Law thrown in there just for comedic value. And if one of them is leaking, I bet the other five aren't far behind.

What is the range on the meter set on when you are taking these readings?

My thought is If the A/F numbers look that good, I wouldn't worry much about the plugs being light. I've heard (read on the internets) that the old method of reading plugs doesn't work so great on todays fuel using leaner ratios. Burns so clean that lighter colors often result. That toasty brown doesn't happen as much as it used to? How many miles you have on the plugs? I guess if you're thinking it might be a relic of a previous situation, you could buy new plugs and have a fresh read. As for the ignition box, I don't know anything about it. Hopefully someone else can chime in.

That's exactly what they did starting in 77. They went back to vents on both sides (as opposed to 75 and 76 which only had the vent on the right side) and changed the intake location from the front of the car to inside the cowl area instead. Just another reason why 77 is better.

Well (in theory) the only change you would/should see with the CARB system connected is that it should run leaner at the low end of cruise because that's where you should be pulling air through the can into the manifold. 1/4 pedal maybe? Somewhere around there. It should be a pretty tight spike as the ported vacuum that actuates the system cuts off pretty rapidly when the throttle plate isn't over the port hole.

Those numbers look great. I'm sure you're happy with that! I'd love to see how your engine dynos. Did you ever put your CARB system back together? Are those numbers with the system connected using the valve in the cap? Also, out of curiosity, can you see a distinct change at the upper end of cruise when the WOT switch closes and the enrichment kicks in?

Well I haven't gotten the insulators off the intake manifolds yet, so I don't know which side the gaskets will end up on. I do, however, have the situation with gasket material petrified onto the manifolds where the balance tube goes. I've done some work with the paint scraper razor blade, but got skittish the second time I dug in. The first time you tell yourself "OK, I slipped once... Let's not do that again." And then you do it again. I believe the aluminum is softer than the gasket material. So I haven't caused any unmanageable damage yet, but just wondering if there's a silver bullet. Granny says "no", but I'm hoping he's just not hit on it yet. Maybe I'll try the shallow pan Mr. X suggested, and maybe put the whole thing in a bag just to see what happens. Thanks guys!! So before I crawl back to my hole... There ARE concoctions sold on the open market that are named "Gasket Removers". Is this just snake oil?

@Racer X, Any clever suggestions for how to keep the gasket wet with solvent for a couple hours for it to soak? I've tried the saturated rag on top method in the past, but it dries out too fast. I don't think I want to drop the whole manifold pair into a full tub of the stuff. How have you kept stuff like that saturated?

Hahaha!!!