Captain Obvious

If I found the right stuff, it has a max hardness of C35, so it shouldn't be a problem to machine. Yesterday I was thinking it could be an issue since the little poking around I did turned up that the chromoly stuff can be case hardened all the way up to like C60 or so, and that could be a problem. I'll be the first to admit that I'm pretty far out of my element with the metallurgy stuff. I know just enough to be dangerous. I'm just asking questions poking around trying to help out by looking for holes. The overall drawing makes perfect sense to me, and one suggestion would be to include some feature to be able to turn the threaded rod by itself. Maybe a set of flats out on the non-business end or a cross drilled through hole for a rod or something like that? I'm thinking to help thread the rod onto the spindle, or remove it from the spindle when you're done? Maybe in some rare situation the spindle pin could turn as you're trying to pull it? You could use two large nuts as jam nuts in most situations, but I'm thinking something more elegant. Not sure you would ever really need it, but maybe? Boy, I would have loved to try this thing on the last pin I pulled. I don't know if it would have worked, but sure better than what I ended up with.

Are you buying it annealed or already hardened? If it's annealed, then yeah, it's a breeze to machine. But of course, it won't be hardened. If it's already hardened, then machining is more difficult. I guess once you punch through the case hardening, it should be softer inside, but then again... so will the threads. I'm no expert in the field... Just thinking out loud. Was this something from McMaster? I took a quick look over there and didn't see anything that clearly stood out. Everything was too long, and the best stuff they had was grade 8 and it cost more than what you listed above.

Cool. Sounds like a plan! Your machinist buddy should ask "Well, how hard?" You should have the hardness numbers handy when you talk to him. In general, "Hardened" means "Must resort to grinding - Cannot be cut with conventional means". When you get a chance, snap a pic of the coupler and pipe options that you've got laid out. Would help with the visualization. (For me, at least. :stupid:) Another idea? You could maybe pick up a relatively long 1" diameter bolt at a big box store for a dollar or two and lop off the head for proof of concept?

Nice sketch! What are you missing? It's going to be extremely difficult to machine that rod if it's already hardened. You could grind the OD down to 0.75, but putting in those internal threads is going to be a royal b*tch. Other than that, I don't see anything obvious. Is the 1" black iron pipe intended to slip over the threaded are? I'm just wondering if the internal weld bead in the pipe is going to cause problems. Also, I doubt thrust washers are going to be rated for the load you intend. If your pins are like the ones I've messed with, you're going to be putting a lot of force on it. A whole lot. What's the dimension of your typical 1x14 hex nut? Might not be as big as 1 1/2. I think you'd have to buy a whole wrench set at Horror Fright... You can buy singles elsewhere, but you'd pay as much for one quality wrench as you would for the entire set of HF junk.

Looks great. Did you do the cad plating yourself, or did you send it out?

Huh? What? Someone want to over-engineer something? What can I do to help? Haha!

I've done this and can vouch for the claim above. I didn't actually time it with a stopwatch or anything, but it was at least thirty seconds of idling, and maybe as much as a minute before the engine started misfiring. If you haven't sucked fuel through the pump by then, you've got other issues. Oh yeah, and if your idling engine sucks the bowls dry in less than twenty seconds, then you've got other issues as well. :bulb:

If that's the case then I think you've got other leaks elsewhere. You'd be hard pressed to suck that much air past a well fitting throttle shaft.

Here's your pic that I modified. I've added hash marks for the needle stations and from that you can see that the SM ends before it reaches station #14. However, even with the piston all the way up, you should be running somewhere between stations #12 and #13, so I don't think it matters. Interesting thought that the literature leads you to believe that it would have a true functional station #14: Anyway, it's all academic at this point, right?

I'm no authority on needles, but I just asked about the plating because I've not seen OEM (Nissan stock) needles that have been plated. Everything I've seen that I was positive came from Nissan was unplated brass. Now mind you... that's maybe twenty Nissan needles, so as I said, I'm no authority. Only plated needles I've seen were supplied in aftermarket rebuild kits. I've got a pair of plated N-54's and a pair of plated M-49's (from memory) from said kits on the bench right now. So, I'm drawing a distinction between OEM (Original Equipment Manufacturer, Hitachi in this case) and "OEM" ("form fit and function same as original, but not necessarily made by the same mfgr"). All that said, I did a little photo editing on your original pic and can tell you that the length of the N-27 needle you have there is the same as the ones I have, and the SM is a little shorter than the literature would lead you (me?) to expect, but not by much. It's missing the narrowest station (station #14), but even with the piston all the way up, you would still have needle in the nozzle, so it doesn't matter in application. I don't have the pic uploaded, but I will do that when I get a chance.

There are no seals on the throttle shaft. However... That's quite the leak to cause that dramatic of a drop in manifold vacuum. Is your throttle shaft all floppy and loose in the throttle body? I would be surprised if you didn't have something else going as well.

Thanks for the pics. Not as much of a length difference as I was expecting. Looks like less than one station. I'll double check the length on some of my needles and see if I can figure out where the original confusion lies. Do you think that silver needle is OEM Nissan, or do you think it's aftermarket?

And that's why I was looking for a ballpark number. My mixture screw was about fifteen turns out, and it seemed way too far. As for the AFM adjustments while running... I was doing my check at idle with the TPS idle switch closed so there shouldn't be any conflicting signals. My engine seemed to like more fuel at idle even with the idle enrichment switch closed. Might be related to a mixture screw that is fifteen turns out.

Forgot to mention... I ran my idle mixture screw all the way in as I counted turns, then I took it completely out, cleaned it up, and then put it back to where it was originally. Anyone have a good starting point for where the mixture screw should be? I know they will all be different, but a good ballpark starting position. I think mine is way too far out. I'm barely catching any of the sealing rubber and I'm assuming my PO messed with it. Might explain why my idle likes more fuel, but not less.

Nice! Would you do mine?

Today I inspected the gaps along the sides of my AFM vane and found that the gaps were slightly wider towards the tip than near the fulcrum. In other words, it appeared to me that the vane is in fact bent by accident, and not designed that way from the factory. So, with that in mind, I performed FastWoman's double anvil straightening method, and here are the results. Not perfect, but about as good as I could get it without taking off the waffle side and pulling the vane completely out: Here's my anvils. The metal one was my backup and went in through the downstream side for support. The wood block was my bending instrument and was inserted into the upstream side and hit with a hammer. The tube taped to the back side anvil helped direct the force nearer the tip of the vane because I couldn't get on it square due to the shape of the AFM body. Results? Didn't notice any change. Still runs fine. :laugh: So after I straightened the vane, I also played around with the vane position by moving the counterweight. The RPMs dropped when I tricked it lean and the RPM's went higher when I tricked it rich. In other words, it seemed to like more fuel, but not less. More tuning will be required.

I was messing with the throttle body on a Toyota Highlander and I don't believe the IACV uses a quadrature signals. IIRC, there were only two wires to it and I think it used a DC signal in conjunction with a permanent magnet. Analog like. :bulb: Wasn't "stand alone" as it was an application specific wart on the bottom of the throttle body, but it wasn't stepper. Looking at the design, it seemed to me that it would be difficult to control. Must be a fast loop... Another tidbit... My AAR was weird, and I finally figured out that it was intermittent. Finally failed hard and then was easy to diagnose.

I didn't get the chance to pull the AFM back off the car to take a better look at that bend in the vane, but I'll reserve judgment on the intentionalness (just made that one up) of the bend until then. In the meantime, I mentioned earlier that I believe my PO messed with the AFM settings. The glue glob on the lock screw for the clock spring gear has been pulled off the head of the lock bolt and some of the plastic gear teeth have marks on them (presumably from a screwdriver blade). So, question is... Is there any way for me to tell where the AFM was originally before anyone messed with it?

Bugs me too. It's just so open ended... I'd pay the shipping for you to send them to me for yet another set of eyeballs, but I can't believe there would be anything that I could possibly notice that wouldn't have been picked up by ZT. After all those pages of investigation, I just hate not knowing. :paranoid: Hey, now that you don't need those carbs to run the car, how about that shot of the SM's and the N27's next to the ruler?

Thanks Willoughby! You may have just saved me from "fixing" something that was never a problem in the first place! So the jury is still out on whether that bend is intentional or the result of a misfire. Glad I didn't jump the gun and start straightening it yet! Blue, Yes that gap appeared to be consistent to me as well when I was looking it over. I didn't measure it, but it eyeballed pretty even up the length of the side. That, and the consistency of the bend itself is why I was originally questioning whether the bend was intentional or not. So, I'll measure the side gaps, and if they're even along the whole side(s), I'll assume the bend is fluid dynamics black art. More news as that develops. Fastwoman, Yes, your dueling anvils make sense. I was just thinking that if nothing went sproing, it would be easier to adjust on the bench. Although, it seems I may not have to be doing anything with it. That would clearly be the best answer!

I'm sure your really really not supposed to do this, but... Can I take off the other side of the AFM to get better access to the vane? Might I even be able to take the vane completely out to work on it?

Mine runs fine at all throttle openings, but I believe I'm running a little rich. However, I'm still very new with the car and haven't even had the opportunity for a decent shakedown yet. I've been finding and fixing the problems as I discover them and haven't gotten to the point where I'm ready to really start "tuning". I believe my AFM has been tweaked by the PO, and that may be why I'm rich. In other words... If I put the AFM back to stock I may end up lean. Yup. I'm sure it's cast. At this point, I'm glad it's as flexible as it is. :surprised

Junk. I'll go $55 plus shipping. :pirate:

That's exactly why I wasn't sure if it was supposed to be that way or not. Fluid flow is weird stuff and since I'm sure these AFM's were highly characterized at the factory, I wouldn't be surprised if that feature was intentional. But unfortunately, it sounds like it's not. Crap. And that answers my next question of "OK, so it's bent. Does it really matter?" I was hoping that even if it was bent, it didn't have a great implication on how the car ran. Now I gotta do something about it... Only if you come over and help me tune the system afterwards.

Yeah, no kidding. The implications, as I'm finding out, are deep running. So not only am I finding blasting grit in places it shouldn't be, I've also realized that all of the original chromate plating has been blasted off the steel bits and has been replaced with paint. Looks great until the first time you wipe something with carb cleaner and take the paint off exposing the untreated steel beneath. I would much rather deal with a little dirt, grease, oxidized aluminum, and old chromate. Even if it's starting to fail in spots.