Zed Head

Paint 3D. Tried to get a 3 way comparison. The original CanTechZ color has more "pop".

I wonder if somebody could build a U-shaped device that you could slip over a nut on the threaded end of the shaft. Then you could turn the nut against the inside of the U-shape to push the lock bolt out. Heat on the piece at the end would also cause expansion that might be enough to loosen the fit on the shaft.

You could use a drill and a piece of hose to turn the input shaft and run it through the gears. With no load you won't need a clutch. Or you can just stop turning while you change gears. At least you'll know that things spin in each gear and don't pop out. It's possible to get everything put together with two gears engaged. So at least spin the input shaft by hand to be sure you didn't do that. Did you remove the clutch pivot pin/ball? If you did you'll want to seal the threads on it. I had a wrecking yard transmission that had a leaky pivot pin and you couldn't tell until it was installed and you drove it.

Someone asked about using the computerized paint matching. I've done it for house paint and it's amazingly accurate. If you have a part that hasn't seen sunlight, like the inside of the gas fill port cover, or a chunk of the sound deadener under the spare tire, you'd probably get a good match. They don't need a big piece.

2+2+5 =$14,280. https://bringatrailer.com/listing/1978-datsun-280z-22-9/?utm_source=dm&utm_medium=email&utm_campaign=2021-03-30

179 x .8 = 143. You are right on the edge. Most engine builders today use 10%, not 20% (actually 80% of highest by Nissan's description). Your backfiring and popping could be caused by "missing". Raw fuel in the exhaust pipe.

Did you measure cylinder pressure correctly? Do the SU's require a person to prop the pistons open? Seems like they'd block flow otherwise. That is a lot of variance, you have some weak cylinders, if you used the proper procedure. With the popping and backfiring you're seeing, I'd guess that you have some leaky valve seats. A leakdown test will tell you a lot. Some people simplify the leakdown test and just push air in to each cylinder, and listen for leaks. Crankcase, exhaust pipe, or intake manifold. I'm going to guess that your engine is damaged or just worn. Your plug gap looks right for your Pertronix. You're using the Ignitor I which is not the high energy system. You can't run a big gap with that one. The SU's are known to leak at the throttle blade shafts. @Captain Obvious and others have written about it.

Paul Revere and The Raiders, somehow, led me to here...

Are you bidding? Don't want competition? No link. That's pretty good money for a fiberglass 240Z.

I bought a 78 parts car cheap mainly for the 5 speed. I ended up using the engine in my 76, it was in much better shape. Just planting a seed. Your engine looks like somebody has spent too much time in there. I don't think that Nissan numbered the pistons so the mismatch you saw might not be important. I see some pretty deep scores in the cylinder you showed, so you might need new pistons anyway. But then you're looking at pistons, a bore job, rings, all the extras...spendy. Any L6 engine up to 1984 will drop right in. A 280ZX parts car with a 5 speed would be a nice find.

You should just do a light sanding and a clear coat on the exterior. It has character.

Pictures would be neat. Are the ends bare metal or painted? Who made them? I think that factory springs are all flattened to fit the seats. My 280Z springs were. Use the @ to notify Carl Beck. He still visits. You'll probably want to post some details, like part numbers and stuff. @Carl Beck

The super silver is selling today. Doing pretty well. $36,000 and a bidding battle in progress. Edit - didn't sell. That's what happens when you modify. The value is personal. Maybe not objective. https://bringatrailer.com/listing/1973-datsun-240z-153/

How about a shot of the bottom of the cylinder head? You can stand them on end, they'll balance. Seems like somebody over-revved, or had some stuck valves in the past, or didn't get their cam timing right during install. The dings are covered with soot so they're not fresh. Check your cylinder head number too, see if it's an N42, that would have come on a 75 engine.

Sunday might be the best day to end an auction. $42,240 for a 72 that's nice but doesn't seem that nice, plus it has a sunroof (no offense to the buyer. Or the seller). Green is a good color though. The seller apparently had a reserve set higher than the final, but took it off. Must have been close. https://bringatrailer.com/listing/1972-datsun-240z-171/

And another silver car. Crusty 71 4 speed. https://bringatrailer.com/listing/1971-datsun-240z-171/

I posted the link to Bring-a-Trailer so you could see what was happening. The well-done resto-mods and the very original cars seem to get the money. In between, not so much. And yes, it seems like a recent thing. Hence, the spotlight. https://bringatrailer.com/datsun/240z/

There's a person or two on the forum who've said that they wouldn't have done things if they knew that the cars would be worth so much in original form. That's the point. You're not restoring, you're modifying. It's your car, people, I think, just want to be sure you know that your changes might detract from future value. Beyond that you're really just asking opinions about what looks good. That's subjective. Silver, green, red, brown. Favorite colors, as many opinions as there are colors. Good luck with it.

Like madkaw says, vacuum leak probably. You're tuning at idle for the leak, then when you get on the throttle the leak has less impact and your tune is wrong. Motorsport has good advice about the Pertronix and coils. Lose the ballast. https://www.thezstore.com/page/TZS/PROD/classic11g/12-4020 Coil Notes: The only performance coils that should be used with the PerTronix Ignitor, the 40,000 volt Flame-Thrower canister coil's higher voltage allows larger spark plug gaps for added power, smoother response and better fuel economy. They are oil filled for great heat control, and internally resisted. Legal in all 50 states and Canada (C.A.R.B. E.O. #D-57-10). The 3.0 Ohm coil is not for use with the factory (or any other) ballast resistor. If your setup requires you to keep the ballast resistor, please select the 1.5 Ohm coil above (see Related Items below for more information about the 1.5 Ohm PerTronix coils).

Nissan changed the hose routing in 1977. Here's something I've found useful. The cars on BAT all have numerous pictures and usually run like tops. Here's a 78. (Funny though, I see that the guy left the brake fluid reservoir open. Still got a good price.) https://bringatrailer.com/listing/1978-datsun-280z-84/

In short - your symptoms seem to fit an engine that is not pulling through the throttle body. Could be pulling through the PCV system, or the EGR system, or the valves and/or pistons are not generating enough suction. I think that explains the AFM vane not moving. There's no air flowing through it.

Could also be that some valves got bent during head installation. A cylinder pressure measurement will show that.

Who rebuilt and installed the head? Is it the one the car came with? Your PCV hoses look right, I couldn't see that the one in front of the AFM was an elbow. I'm afraid you have the typical internet dilemma of assuring everyone out here that things like cam and ignition timing are "right" and don't need to be verified, yet you can't get the engine to run right. It's hard to get too involved when you don't have verification of those important things. No offense, but the thought that runs through your mind is "why should we believe this guy"? Anyway, two things that come to mind are: 1. a rotten EGR passage, where the blockoff plate doesn't work because the passages themselves are rotten. Somebody had that problem a few years ago and he had all kinds of odd problems with the way the engine ran. I think that he might have found it by measuring intake vacuum. It was much lower than it should have been. You might take an intake vacuum measurement since it is a measure of how the engine is pulling iar through the manifold. It's a clue. 2.

Here's your other thread, in case anyone thinks they've seen this one before. Reptoid is right, there's something off about your PCV system. Looks like the valve cover is open to the atmosphere. That's not good.

How about a description of a normal cold startup, warm up, then the driving experience? It's hard to tell what is really wrong. Make sure you distinguish between tailpipe "backfire" and carburetor popping. Does it just not "go", or does it go with a lot of bucking and back or front firing? A video would be great. You can tell a lot by how an engine sounds.