Zed Head

More silver. Another 78. One just sold for $29,000, above. Might be too late, the market is saturated. This one has had a recent oil change though. And it has the mini towel bar, for the one next to the sink. And a rear luggage rack. https://bringatrailer.com/listing/1978-datsun-280z-86/

How about a picture of your pile of parts? Before and after is always good to look at.

Silver 78 is up today. Already at $21,000. Sold for $29,000. Not bad for a big bumper car. https://bringatrailer.com/listing/1978-datsun-280z-85/

This is probably a better forum for reassembly, I'd think. No offense to HybridZ.

You misspelled forum.

The UV problem happened again in the late 80's. All of those old Ford and Chevy trucks you see with gray primer showing after large pieces of paint peeled off were because of a change in the E-coat chemistry. It was actually UV light passing through the coating and degrading the bond between the coats. Everything you wrote sounds familiar, just about ten years too early. It would be good to see some history showing what, exactly, Datsun was doing on the 240Z's at the factory. A second clear coat on top of wet base coat would be different than a clear coat on an already baked base coat. I think that 73 has a more modern clear coat applied than any 240Z ever had. It's not a "period correct" paint process. Today's clear coats would be thicker than the wet on wet clear. I still think that 73 looks too shiny. Too "wet".

I used to work for a company that made paint materials. One reason clear coats became really popular in the 90's was that they could hide a lot of base coat defects. Water-based coatings had orange peel and without the clear coat it was very evident. If you look closely at most new cars' paint you can see the orange peel under the clear coat. Look at your reflection in a door panel and it will be wavy and distorted. But the surface looks shiny and smooth.

I can't find anything definitive about what Datsun/Nissan was doing but my understanding was that clear coats weren't used in high volume until the 80's and mostly on high end cars. I remember guys getting clear coats on their hot rods in the late 70's but that was a custom paint job. This article suggests that the late 70's/80's was when they really came in to high usage. https://www.paint.org/coatingstech-magazine/articles/brief-history-automotive-coatings-technology/ "As previously discussed, thermoplastic acrylic lacquer automotive coatings, given their excellent appearance, were the major automotive topcoat used in the 1950-70s. However, these lacquer topcoats did have one significant drawback: they had weak exterior durability. After about one to two years’ exposure, the coatings would begin to degrade, and aggressive waxing was needed to “bring back the shine” of these systems. By the 1980s, the automotive manufacturers were requesting better durability for automotive topcoats, as consumers were now expecting their cars to last at least five years, and they wanted the car to continue to look like it did when they first saw it in the showroom. " This Toyota page shows a clear on a solid as a one step/one bake process in 1973 but no clear top coat again until 1990. https://www.toyota-global.com/company/history_of_toyota/75years/data/automotive_business/products_technology/technology_development/materials/painting/index.html

The BAT crowd seems oddly excited about it, but most of them are just talkers/value pumpers/fans. I think the shine on the paint is from a clear coat. That's what clear coats are for, but Z's did not have them back then. Here's the silver 71 for comparison. The shiny 73 is already $1000 more. You never know until the last two minutes though. https://bringatrailer.com/listing/1971-datsun-240z-164/

The yellow arrows confuse me! I'm just a primitive cave man...

Too shiny! That's the third silver Z up for sale. I'm betting on originality for big money.

$17,000 for the 83 ZX Turbo hooner, whoosh, whoosh. https://bringatrailer.com/listing/1983-datsun-280zx-turbo-12/

Intermittent problems are the hardest to solve. I'd set some things up so that I can get information when the problem happens. A fuel pressure gauge would tell you about fuel supply. Watch your tachometer needle closely when the hesitation happens. Could be a spark problem. The fuel filter thing might be a red herring. And, it's always good to start with a fresh tune-up when a new problem shows up.

I Has it ever worked right? Never really said. The "standard" coil might not be the right coil for the ZX distributor. Or it might just be 50 years old. Are you using the return line on your carb setup, and does it have the restrictor in it? The restrictor actually keeps the fuel pump from over-drawing from the feed side. I just realized this when you said your filter gets drawn down. With the pusher pump at the tank you wouldn't have this problem. But the mechanical pump is pulling and pushing. If there's no restrictor it will be easier to push than to pull. You might be starving your pump. It's still kind of early here so my thinking could be off.

Maybe this one.

I'm the Wiz...I'm the Wiz.. Reserve not met, at $28,250.

Just a comment. This post might be readable on a phone but it's just a huge block of letters on a computer. In case you're wondering about responses. Kind of looks like Ginsberg wrote it. Stream of consciousness stuff...

The temperature controlled timing advance is done by another set of points in the distributor. If you have that system it might be that one set of points needs adjustment. Have you been under the distributor cap recently?

What do you mean by "digital" signal? You'll need some sort of converter to use a thermistor or thermocouple reading. That might determine the type of sensor you need which could determine where you put it.

What changed? You said it ran right for 20 minutes. Your fuel pressure reading is too high. What happens to it if you remove the vacuum hose to the FPR?

Silver 240Z's are popping up everywhere. Weird. Looks good. One thing that might fit some of your symptoms is a sticking vacuum advance breaker plate, if you have vacuum advance connected. You'd have high advance at idle and low throttle, then it should retard as you open throttle. The detonation might be from high advance because the plate is sticking. Pull the cap and see if the breaker plate moves freely. Mark Maras's suggestion will tell you if it's a fuel/air ratio problem. You should try what he suggested. Pull the choke.

This one? Or lonetreesteve's, #534 above. It's a Z-Orama. https://bringatrailer.com/listing/1971-datsun-240z-164/

Originality and that citrus color. It even had a bad dash and a header.

The Lemon Green 73 is up today. Sold for $40,140. https://bringatrailer.com/listing/1973-datsun-240z-139/