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Captain Obvious

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Everything posted by Captain Obvious

  1. Well I guess I'm going to test that statement about the new aftermarket valves being the same front and rear. I just put in an order on rockauto for rebuild kits for the 72. They call out two different part numbers for the kits and make it clear there is a different one for front and rear. So I'm going to soon see why they spec different kits for 72 F and R. If it's not the needle valve length, then I don't know what it's gonna be. I guess I'll let you know in a little while when the kits get here!
  2. Oh, and it's clear to me that Datsun really messed around with stuff in 72. The float valves are unique, the lids are unique, everything is different than the previous years. It looks to me like they were chasing minutia. Some engineer realized the slight geometry differences between front and back carb bowls when they mounted on the car and convinced management he could make it better. I'm thinking they should have just left well enough alone. Also makes it clear why I was having a hard time getting these carbs right... They're all kinds of wrong inside from previous owners.
  3. Yeah, I'm measuring including the rounded top portion. Essentially I'm interested in "how far does the valve stick out of the bowl lid", and that includes more than just the hex portion. So I'm measuring everything from the sealing washer surface to the top of the valve (not including the movable internal bits). Like this: So this is my (cracked body) 72F valve. I get .806 (20.5mm), That makes sense since the TSB mentioned earlier says they lowered the bowl level for the 72 front carb by 2mm. Both the valve and the bowl lid ears got 2mm longer for the 72F, so all the number
  4. You don't need a welding rep. You need a metallurgist and an automotive transmission engineer.
  5. You want the gears to be hard enough to be "tough" and "wear resistant" but not so hard that they're "brittle". And you want the heat treat to be predictable through the part. Welding heat would definitely take the metal above the temperature where the original heat treat would be changed. And without knowing how it changed, it's risky. After welding, it might be harder, softer, or exactly the same. It's all a crap shoot and the only safe thing would be to start over. And even that comes with issues because you don't know what the original spec was. I just see the whole thing as risk
  6. Thanks guys for the float valve measurements. I did measure from the base all the way to the top of the valve. I figured overall length was the important parameter. I would assume that the dimension from the end of the hex to the top of the valve would be pretty consistent within the same manufacturer, so I ought to be able to convert your measurements to overall. I wouldn't complain, however, if one of you guys would measure the length from the bottom of the hex to the rounded top of the body. Just don't catch the little retainer spring under the caliper jaw. Easy peasy. Also, I fou
  7. Without a complete professional heat treat afterwards, there's no way I would put welding heat to an internal transmission gear like that. It's just a reverse idler, right? Only engaged when you shift into reverse? I'm no transmission guy, but unless it looks like one of the teeth is going to come off and get wedged between other teeth (and avalanche), I would just run it the way it is. Make sure your clutch is adjusted properly, come to a complete stop before shifting into reverse, and put the trans into any forward gear first right before you grab reverse. Do those and it won't get
  8. The 1972 round tops (3-screw) used different float needle valves in the front an rear carbs. Does anyone have the length measurements for the original long and short 72 needle valves? Here's a pic for (what I believe are) the earlier 70-71 round tops. The length of the valve (just the valve without the sealing washer) is 18.5mm (0.729 in😞 After all that I've read, it is my belief that the two 72 valves should be on either side of the valve measured above. In other words, I'm thinking the front valve should be longer than 18.5mm and the rear should be shorter than 18.5mm. But witho
  9. Under certain circumstances, exhaust gas is intended to be ported into the intake stream to reduce some exhaust emissions (compounds of nitrogen). Now about those "certain circumstances"... Those certain circumstances never include "at idle". At idle, the EGR system is disabled because it tends to make the idle unstable. And when you're not at idle, amount of vacuum applied to the EGR valve is modulated by the BPT valve so that the higher the engine load, the more exhaust will be recirculated. I'm thinking that what you have done is applied 100% full open exhaust recirc under conditi
  10. Hmmm... I had a bunch of comments, and then I tried a different (not obsolete) browser and most of my comments became moot. But just for posterity, here's what I found using my ancient version of IE: 1) Pictures no longer show up in-line (at least not when you are not logged in). Now if you want to see the pics, you need to click on each one individually. 2) No delineation around quoted material. Makes it hard to figure out what was quoted and when the quoting ends. 3) No delineation between different posts on a thread. Makes it a little difficult to figure out where one post en
  11. I don't remember the progression of events from the whole rebuild thread, but these flat tops are not assembled correctly. The front and rear bodies are swapped and will not work as assembled. I'm guessing this was just a proof of concept pic to show off the shiny new plating.
  12. Love the pic with you next to the new Z. I think you look better than the new one. But that's just me.
  13. Just to make sure you're numbering the pins on the 35 pin connector, here's a pic looking into the harness. You can use this to double check your results:
  14. Datsun changed the power valve a number of times trying to get it right. I think the "green dot" version is one of the later versions. Here's a pic of one of my power valve springs. It looks like the one from your green paint mark version:
  15. I wouldn't have expected that. That would have been quite the surprise!
  16. Yes, mine has been filled in a lot on the left, and around the spark plug as well. That's not just a shave that made the spark plug area look like that. I was also thinking that the wall down towards the valves was too abrupt. But that could easily be sloped off a little more gradual by removing some of the infill. By it's next owner.
  17. Maybe she's just happy seeing light at the end of the tunnel when you come back inside the house and aren't living out in the garage? Haha!
  18. Here's a pic of one of the cylinders. Not as much material added as the one in your pic, but definitely a bunch added. Does this look reasonable? My days of building up a 300 bhp motor are behind me.
  19. That's awesome!! So just how big was the smile??
  20. Some notes about the temperature sensor and the thermotime switch. There are two trouble spots with the connectors. First trouble spot that the electrical connectors up at the thermostat housing are the same style and it is possible to get them mixed up. Other than the color, I'm not sure if there's a quick visual way to tell if they're correct. (If original stock) One of them is brown, and the other is gray. You can see the colors in the pic you posted, but I don't remember which is which. The second trouble spot is caused by the fact that they used two short pigtail harnesses to th
  21. Jon, What's something like that worth? I've got a P90 here collecting dust that someone has done that kind of work to. Not quite as extensive, but similar.
  22. Have you done any of the testing from the EFI handbook (commonly called the EFI bible)? https://atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf Most of the testing there is done at the big ECU connector. I would be interested in hearing what your coolant temp sensor resistances are both cold and hot. And about pulling off a plug wire to check for a misfire... Not good for the ignition system. A better way is to pull off the injector connectors one at a time and see if the idle changes. Lastly, your compression numbers are definitely low. Did you block the th
  23. Pooky, I'm not sure I understand the problem(s) you're having... How bad is the problem? Is the car drivable? What's the worst of the problems? Maybe we can start there and knock them out one at a time? Also, @mgood is and active member and he's in the Pittsburgh area. Maybe he has some input for local help?
  24. Well regardless if they flow the same, that's pretty annoying. The color may not matter, but on my engine, I would want everything to at least match. So I have no idea if the size of the opening on the bottom is the only thing that would affect the flow rate. I kinda doubt it. I suspect there are other internal geometry areas which could affect the flow rate too. In other words... Just because the hole in the bottom is the same, I wouldn't assume they flow the same. You could test them to compare the rates:
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