Richie G

Thank you both for the help. I'm in a bit of a panic mode because after giving up on replacing this valve due to its welded on locked tight strength, I put everything back together. I started it up and now I have this major knocking which I'm hoping is just the valve itself. I can't imagine it being an engine knock from what I've done, it was running very well with zero sound at all prior to me attempting to do this. The pitch of this seems too high to me to be the engine itself, anyone have an opinion? Could I have done something by wrenching on the valve that somehow damaged the air galley in a way that this happened? The valve may have been punctured when I was trying to see if it was operable.

As I march towards first road test I've come across a few unexpected things I'm dealing with, one I think is a too rich mixture. I say that because I changed the plugs and man they were sooted black as coal. This engine was rebuilt by the PO about 3 years / 2500 miles ago so I'm going to give some leeway here as I am trusting it was done right. I know what they say about assuming lol, but its a starting point. I've read a bunch of material on how to balance / tune the carbs and most people say start with the emissions before attempting to balance the mixture. So I changed the pcv valve (the old was barely working i see after it was off) and was attempting to change the air pump valve but man its on tighter than Ive ever experienced. Ive tried pb blaster and still nothing seems to want to unfreeze this thing. I'm scared to wrench on it too hard for fear of cracking or bending the air galley. So i figured well lets test the 50 year old valve and see what we got. I connected a hose and can't blow into it at all which is where my questions lies. With it attached should I be able to blow into it or is there some back pressure in the air galley that would force it closed when the car is off? i can easily blow through a new valve but its in hand not attached to the car. My other question is if it is seized shut and the valve doesnt work at all, what does that do to the performance if the pump is basically useless and cant get any aux air into the galley? Could it be a source of the mixture issue? Sorry if these questions are newbie but its a specific topic I can't seem to find an answer to here.

I'm working on the glove box lid, had to repair the hinge, repaint the hardware, etc. So like a dope I left some cleaner on the lid too long and it discolored it 😞 I knew better but got distracted with something, lost track of time, and came back to a faded grey for the color of the outside lid. At this point I was open to trying to paint it and since I have a bunch of the SEM stuff for the panels I'll be doing next month I figured I'd give it a try. Then I had another idea. I recently restored the radiator and used this to paint it when done. It came out beautiful BTW I had also used it for the inner door sil kickplates and those came out great too So I figured lets give it a try on the lid. Well, it came out nearly perfect match to the dash lol. This rad paint sprays on so thin since its made for radiator fins and dries so fast it was really easy and i didn't need to go through all the SEM prep and sandless and all that. Pictures don't do it justice but here goes When I'm ready to do all the panels I'll give this a try to see how it holds up and report back. Maybe an easier alternative for some.

I jinxed myself! i spent the night struggling with getting the heater panel in, cables run, had to weld the map light leads, and then the radio faceplate to secure it all down. it was a B!@#$ to get the 4 screws aligned, of course like so many I cracked one of the mount holes of the faceplate, and then after all that the seek scan is no longer working 😞 i still get that sweet sweet sound of am talk radio though lol. with the amount of work it took to get it all mounted i think i can live with using the tuner knob by hand 🙂 if i get this BT gizmo i'll report back if its any good.

I've had a seek scan AM and nos pointy tip on the shelf for two years and finally got around to installing them as i get closer to road ready. I tested it yesterday and it all works perfectly to my pleasant surprise. Antenna up down no issues, seek scan even locks in on the 4 crap AM stations in my area, the lights and led on the tuner works. i'll be honest i was expecting much less but man I'm stoked its all working. Of course the sound is crap with a single speaker back there but the speaker is new and doing as best it can. now I'm getting greedy and want to expand my music selections lol. Anyone try anything like this before? https://www.ebay.com/itm/134813988497

Mystery solved. So for me I guess the previous owner just happened to have a series one hose use that and when I inherited the car I copied his selection. Sounds like no harm no foul correct? You would think if they preferred moving it to the vertical position why wouldn't they have just made a tube with only one location? Why manufacture a tube with two additional holes that you have to stick bolts in?

Weird right, couldn't find a single pic anywhere on any site of that setup. I must have the unicorn lol. That hose does go to the booster, I just replaced it when i refreshed all the old crap hoses. i specifically bought the early series 1 since i had the horizontal fitting. the setup has the typical valve mid hose in the support bracket. that fitting on the tube is just a plane fitting no valve like the type coming off the coolant lines to the carb coollant tube.

After successfully installing that AB Valve from @zKars I just noticed I have 2 bolts plugging openings on my balance tube. Seemed strange to me and was thinking the PO removed some emissions equipment but all the pics I'm seeing and FSM show the tube without these openings. Did the PO grab a later year one? Or maybe this car had some accessory like AC? I did see in the original console the typical holes where ac controls would go but thought maybe he just parted out a console. Any thoughts? Any reason to bother replacing that tube?

You're right, no seat belt light and i notice choke light which isnt in the 71 either. thanks for the quick response and great work as always.

@SteveJ that fuse box picture describing the actual uses, when voltage applied, etc. of each fuse is awesome. i have an early 71, would wiring still be the same? I've never seen it so simply explained before thanks!

I know this is contrarian here, but maybe I'm just lucky or the previous owner already compensated with the hinge and latch, but the Precision ones work great in my 71. I just put them on as part of all the work I'm doing and dont seem to have any issues with closure, lock operation, or the gaps in the seems.

Returned from vacation to find my valve from @zKars, installed and after oil change, radiator flush and fill, and fresh tank of gas she fired up pretty easily. Works great thank you so much all especially @zKars for the part.

Thanks, Im a few weeks away from firing up, will save it and try. @zKars was kind enough to send me a known working one and I'll compare operations.

I should have been clearer the balance tube side is smaller at half inch. The input side is larger at 5/8

Well that seems like shrike three

Saga continues but maybe I have a good one, need someone to weigh in. This 3rd one i received today is "closed" when i attempt to blow air through it at rest. i think that's a good start (except it tastes terrible lol). Connecting the vacuum control port initially i have no pressure held, but, if i close off the smaller pipe like this it will hold pressure. Closing the larger pipe does not hold pressure BTW. As soon as i lift my finger from the smaller pipe it release pressure slowly. This unit looks just like yours @zKars which the seller mentioned came from a good working 260z. One thing i do notice which doesnt seem to matter is the control port seems to have been moved to the opposite side which just means i route my rubber slightly differently unless im missing something there. New one on the left BTW which "aims" the control port towards the engine block rather than on the air filter side. @zKars does this seem to operate correctly like yours? it looks super clean down the barrel just like yours does. If you feel otherwise I'd humbly accept yours and you can DM me for details.

Thanks!!! Should know by tomorrow, will let you know.

@zKars I really appreciate that but I do have one more that should be showing up today that I will check first. And the more I think about my original one being broken makes sense because under certain conditions I did find soot coming out the back of my muffler so wouldn't that also lend to the story of my original valve being broken since I couldn't get any air through it at all to lean out the mixture when required?

Thank you both looks like it's back to the junk pile for a third if I can't get this one to unstuck. Now that I think of it when I received it it still had hoses attached and when I took the old hoses off there was a piece of electrical tape covering the secondary Airport where air would enter under vacuum I thought maybe somebody did that just for shipping but it seems now that they realized it was stuck open and had taped shut the secondary port to prevent full-time air coming into or through the valve which probably was creating a full-time lean air condition hard to deal with.

@Patcon good news bad news i think. So first i tested the old one that had the pieces fall out and has some rattle. wont hold vacuum at all so i think that convinces me that one is trash. the "new" one I was able to find a fitting and pump to 25mmhg and it holds for quite a bit. that's the good news. the bad news is the valve doesnt seem to change, still easily blows through it. So either the valve is stuck open or maybe i need more pressure i can't generate? does 25mmhg match what one would expect under normal driving conditions? assuming this is enough pressure, any idea what would be a safe way to try and get the valve moving again?

I might Maybe one of the attachments from a brake bleeder kit I have might fit and I think I can hand pump some vacuum there I'll try in a little bit and report back good idea.

Wondering if someone can answer / confirm this for me. I just received a valve from a pick and pull that looked like it was in really good shape. It needs some cleaning up but no rattle inside. What's interesting is that the difference I see is that air freely flows through the valve when i blow through it where as the one i took off the car you can't at all. So it got me thinking, this valve as described in what material i could find operates by allowing secondary air in to lean the mixture out when you suddenly release the throttle "When the throttle is released intake manifold pressure falls, and through a small hose connection to the gulp valve, this vacuum causes the gulp valve to open. This allows air from the air pump to enter the intake manifold and lean out the fuel/air mixture, preventing backfiring" And in looking at this diagram i found, seems to confirm that So with that said, would it make sense that the valve should stay "open" for air to pass through when no vacuum is applied at all, meaning i have it out of the car. I would think so right? if a drop in pressure allows the secondary air in then I would think the "at rest state" of the valve is fully open if no pressure when fully disconnected is present. That would mean the one I just received probably is good right? I'm a few weeks away from even installing and firing up for the first time to really tell.

This one. Whatever was going on that night with search also kept giving me a response that my post was missing required information so I might have hit submit a few times I tried to go back and edit and delete post but I guess only administrators can do that.

anti backfire yes 71 240z stock engine

Working my way through the engine bay and starting to take apart and get ready for some work replacing the mess of hoses left by PO. I took the AB valve and corresponding hose off and a bunch of what i would say looks like petrified carbon fell out. Some of it is typical dust and small particles but a few are large and pretty "square" so I'm wondering if this is some sort of broken diaphragm, or gasket or something in there? Or is it just carbon that formed this way? Last i had the car running about 6 months ago I don't recall any backfire, how would I know if this valve is still good? Or is there a way to disassemble and clean it? BTW search seems to be down so i couldn't get anywhere.