Captain Obvious

Oh yeah. Something else that can cause a lean condition under high fuel delivery conditions is a clogged fuel filter. Here's to hoping that it was a simple as that!

The only other small piece of info I can provide is that the wheels operate on a mechanical system where it's normal for it to require more torque to move a digit when it rolls from 9 to 0. That's because when it rolls over, it has to move the lowest digit, and every other digit above it that's changing. In other words, it's a lot easier to spin from 0003 to 0004 than it is to spin from 0009 to 0010. It's even harder to spin from 0999 to 1000. Because of that, if there's a damaged piece inside that is jusssst barely working properly, it would be expected that it would fail first when digits are rolling over. So good luck with it, and if it comes to the point where you need another set of eyes inside one, let me know. I've got a speedo here that I can open up if necessary. I might not know what I'm looking for on yours, but at least I could discuss the guts intelligently.

I was into the regular odometer section of mine, but not the trip-o. You wanted ideas though... Everything is gear driven, isn't it? If that's the case, then there's no way it should be able to get stuck without something skipping a tooth or something. Did all the gears look OK to you? Do you hear any clicking? You can spin the input shaft of the speedometer while it's on the bench to make sure everything is working OK. Won't fix it for you, but at least you won't have to go through all the agony of putting it back into the car before learning that it still has a problem. I don't remember if there was enough length sticking out the back, but maybe you could even chuck up your cordless drill on the little stub and use the drill to turn it?

Yeah, that trip odometer cable... :ogre: Barring complications due to a dash cap, pulling the speedo out would be half the job if it weren't for that trip odometer cable. The speedo is pretty much designed to be able to be removed with the dash in the car. In typical Japanese fashion, they set everything up such that it's supposed to be relatively easy to remove the speedo. The electrical cables have significant extra length such that the speedo can be pulled generously far from the dash before you run out of length, and so does the trip odometer cable. Yes, I said it, "and so does the trip odometer cable". The PROBLEM is that they wrapped the trip-o cable around the HVAC ducting so that it didn't hang down on your knee or get tangled up with anything, and because of this, it's tethered too short to get to the screw to release it. My solution was to reach up and unhook the fresh air duct hose above the drivers knees and untangle the trip-o cable from the duct. Once that is done, there is enough length to get the speedo far enough away from the dash to get to the release screw. I think I also pulled to steering wheel just to get more room in there to work. I was pretty frustrated by the time I got the end of that job, so I may be missing some of the details, so YMMV. :bulb:

Ah HA! That's what I thought!! I was starting to think I was losing it! Let me tell you the full story of what I did earlier today... I went to the home page and hit the Search button. Didn't put anything in the drop down boxes. I was presented with 382 results that seemed to be sorted by posting date. I was thinking "Woo Hoo! They did it!! Posted by date is the default". Then I hit the "category" sort button and the were sorted by category (no surprise there), but then I wanted to go back to sort by date, and..... There's no way to do that? Haha! It's a one way street. Not only that, but it stuck. I'm assuming it's in my cookie somewhere because even if I close the browser and start again, it doesn't revert back to the default sort by date. The only time it was sorted by date was the very first time. Isn't software wonderful? As for the featured results being on top, I don't care for it. I'm not sure what the criteria is for "featured", but there's featured stuff in the list from 2006. I find it disconcerting to be scrolling down through a list of items only to have the dates reset halfway down the list. My thoughts on this are unless someone is paying for special attention (featured), then I would skip it alltogether. And if it is a pay service, I would have it time out... You get 30 days of featured top of list for $$. After that, you're in with the rest of the unclean. There's got to be other people besides me who have input into the new site... Here's your chance!! Speak up!! And Mike... THANKS!!!

I poked around the new classifieds today, and I wanted to say thanks for the work being done. I saw the "Recently Added", and that's OK. I'd still rather have a "sort by posting date" button on all the search results. I can't figure out what is the default sort order? If I hit "Search" from the home page without entering anything into any of the filter drop downs... What's the sort order on the results? I get 382 results and I can't figure out how they're sorted... Also, I couldn't find the map. I'm OK with that, but some of the bells and whistles craving members of the forum might be disappointed? :paranoid:

Usually vacuum leaks have much more impact at idle. Your typical vacuum leak is a fixed size hole (or accumulation of multiple holes) which doesn't change with respect to throttle position. That means the amount of air pulled through the leak is a greater percentage of the total air when you are at idle. When you're at WOT, the leak is still contributing air, but it's a smaller percentage of total and hence a smaller impact. However, the L-Jet system, with it's AFM upstream of the throttle body, is a little wrinkle. If the problem is a vacuum leak causing problems at WOT, it's probably something upstream of the throttle body. As Wade mentioned you should inspect the snorkle between the throttle body and the AFM. There might be leaks in other downstream places as well, but they would have more impact at idle than WOT.

Yeah, methinks you're running lean at WOT for some reason. There are lots of things that can cause that, from the TPS adjustment to a bad FPR or fuel pump, etc... Have you downloaded the FSM and the EFI troubleshooting guide yet?

Let me make sure I understand what you're saying... Are you saying that you put your foot to the floor when you are driving around, and it's fine. But you put your foot to the floor when it's sitting in neutral with no load and it backfires and surges? I was thinking the same as Zed... Have you checked that your throttle position switch is doing what it's supposed to? Wade, FYI... no cat in 77 (except CA?), and no O2 sensor in any 280Z. That didn't start until a few years into the ZX.

geezer, I see what you mean about the thread mount. I wasn't aware that the aluminum knob had plastic inserts to adapt to different cars. Here's an idea... Can you move the base portion from your new OEM replacement knob over to your original knob? Does the new OEM have the same center hole as the old OEM? Sounds like a lot of people have plastic bases that have seen better days... Haha! Maybe I should get into the threaded base business? That and AAR's :pirate:

Something else to watch for is that you've got an automatic... That means that you've got the dual pickup distributor and it's accompanying two input switchable curve ignition module. The system switches timing curves depending on engine temperature. Cold engine = advanced, warmed up = retarded. Controlled by the temperature switch located in the thermostat housing (the two wire device next to the single wire device which drives the temp gauge on the dash). You need to understand that system. Might not have to use it, but you need to know what it does so you can decide for yourself what to do with it.

Would it be a good idea to start a fresh thread that starts out on the right foot?

Thanks E. I was just checking since I didn't hear a peep. I think the map is cool, but I got tired of seeing it on every page. At the top of every page. I would make it an easily activated feature for those who want to see it, instead of so prominent every time. I'm a simple guy who wants a simple list of what's available. I may be in the minority, but bells and whistles are mostly lost on me. A couple sort options are nice though: Sort by posting date (so I can quickly find the fresh new stuff). Sort by distance from me (nice to have when looking for big heavy stuff). Maybe, just maybe, a sort by year for when I'm looking for something that is specific to a certain year. However, I would consider this sort option unreliable due to GIGO. As for sort by price? I don't see the situation where I would ever use it. You only need that if you are comparing lots of very similar items where price becomes the most important criteria. I just don't see that as the situation when buying old Datsun stuff. Hey, I've found eight people selling Z speedometers... I think I'll buy from the cheapest guy?

geezer, Thanks for the follow up with the info on that aluminum knob. If you need to increase the diameter of the flat on the top of that aluminum knob, you might be able to skim a little off the top. Of course, the depth of the shift map numbers will decrease if you do that, but it looks like they're deep enough that you could afford to make them a little shallower and still have enough relief. All they have to do is hold red paint, right? Don't know if that will make the flat area large enough in diameter to fit comfortably in the old hole, but might be worth a try. As for the threaded portion, the hole in the original knobs is already pretty large... Why do you think you would need to make it bigger? Sorry, but I'm not understanding the issue. If you've got the means to cut the map out of the top, then you should have the means to cut the threaded portion down to any diameter you need? Nine bucks, huh?

So is anyone in a position to make changes to that forum reading this one?

Well I think I'm done with knob number two. First coat of stain was "cherry", but I think it turned out a little too red. So for the next coat of stain I went back to the "Golden Oak" and that toned down the red. Also, I was thinking of getting a "Datsun" logo to put in the center, but I wanted to use the thing and didn't want to wait until I made up my mind on the logo thing, so I put the 5-speed map into this one as well. This is the final product: And here's my knob collection: I'll get one of those Datsun logos and see how it looks, but if it's smaller than the 5-speed map, I'll probably end up making yet another knob. I've still got a lot of bowling pin left!!

That's pretty much what I ended up with. One thing to watch for is that the metal cloisonné style maps are a little smaller in diameter than the plastic ones. That's the reason for the flat ring at the top of my knob. I modeled my wood just like the original wood knobs, but with the shift map smaller, you end up with a narrow flat. If the map were slightly larger in diameter, then the flat width would be reduced: It doesn't bother me and I didn't even realize it until I went back through this thread and looked at the other five speed knobs. The point is, that if you're trying to put the cloisonné map into an older knob, you'll have to deal with the moat around the edge where the new map rattles around in the larger opening.

Echo... :paranoid:

For me, the biggest issue is missing the ability to have things sorted by posting date. For example, off the home page - enter "Datsun" into the "Category" drop down box - and hit "Search". I'm presented with 368 autos found, and the second one in the list is a 1979 510 which was posted in 2007. It's been over five years... Is this car still even for sale? Might just be me, but I want to see the new stuff up top. I want to see what's been added since the last time I checked the classifieds. And before anyone goes off and creates some fancy new feature to do that... I'll do that part manually. I remember the last time I checked the classifieds. It was a few days ago. I'll just scan down manually until I start seeing cars that are more than a few days old and call it a day. Don't email me notifications. Don't put the new stuff into some "New Listings" category. Don't put fancy banners around stuff added in the last 24 hours. Don't check my cookies and highlight stuff that was added since the last time I visited the site. I'll do the cut-off manually. I just need the ability to have it sorted by the date the item was added to the database. Also if you go back to the home page and enter the same search as above, but this time limit the years "From" = 1970 and "To" = 1978 (like I'm trying to see all the "early Z cars" just like the old forum version), and after that year filtering, I only get five hits (instead of 368). I'm not sure if it's pilot error or not, but there are a lot more than 5 cars from 70 to 78 in that database, and I don't know why they don't come up in my search.

And forgot... Madkaw, The jury is still out for me as to whether your issue is in the lock or in the switch. I'm having a hard time picturing what could cause the momentary "START" return causing problems without having problems with the spring detents in other positions. Especially if it is catching as you suggested. If your lock has never been replaced and you're still running the same one from 71, then I bet it's worn pretty bad inside as well. You'll know for sure where the issue resides as soon as you separate the switch from the lock assy. There are only two tricky parts to the whole thing... First is getting the entire lock and switch assy off the steering column (and it sounds like you're going to have to get over that hurdle regardless of what the problem is), and second is getting the lock cylinder out of it's housing. Other than those two things, the rest is cake.

Mike, All you need to do is lessen the current load on the "START" contact by using a smaller relay to drive the bigger solenoid to drive the starter and there are lots of relays that you can use for that. The most common mod involves using a Ford starter solenoid as the booster to drive the solenoid integral to the starter, but there are other ways to skin the cat. And don't get hung up on the word "booster". I just made that up to describe it functionally. If you search for "Ford" and "solenoid" on here an the other Z sites, you'll get lots of hits. Poke around and you'll find lots of info. Here are two examples I found that included some pics. From Tony D's cardomain page: http://www.cardomain.com/ride/735451/1974-datsun-260z/page-14/ and from XenonS30: http://xenons30.com/starterrelay.html PS - Sorry for the threadjack.

X2 on Rock Auto for the switch. I've got a 77 and I paid less than ten bucks for BECK/ARNLEY # 2011174. I'm not sure if the earlier cars used the same switch as the later ones, so just make sure you poke around a little and make sure you're getting the right switch for your car. I defer to Wade's attempt to replace the switch without taking the whole lock assy off the column. I didn't try, but it looked "possible" to me. If you do have to get the whole assy off the column, you'll have to mess with the anti-theft screws. I don't have any threads to point you to directly, but I do remember that the removal of that anti-theft hardware is well documented. Speaking of that switch... I was having the traditional "turn the key all the way to start and sometimes the starter won't spin" problem. The problem is a well documented failure of the contacts inside the switch. The switch contacts burn up after years of switching the starter solenoid current and that's the reason people install an auxiliary "booster" relay to drive the solenoid. Anyway, I took my old switch apart to see what was going on and even though it's not directly related to your problem, you can see the detent notches around the outside of the switch housing. I chucked up my old switch to cut off the crimped over ring: And here's the inside where you can see the burned contacts. But to the point, you can also see the detent notches in the silver housing on the left side, and if the problem with your car is the switch, then the root is the detent and spring system: For a temporary solution to my issue, I cleaned up the contacts and bent them around a little for better contact and epoxied it back together. Works great. I also bought a new switch, but it's still sitting on the shelf. I don't want to put it in until I've made that booster relay mod because I don't want to burn up my new switch like my old one did. That was nine months ago....

There are basically two parts to the ignition switch assy... The lock section, and the electrical section. The lock section has a screwdriver style post sticking out the back of it that will turn the electrical section if the correct key is inserted and rotated. The electrical section is the ignition switch which is held to the back of the ignition lock assy by two small screws. Do I have a point with any of this? Yes... The point is that the spring that ensures that the "START" position is momentary is located in the electrical section. There are no rotational springs or detents anywhere in the lock section. All of the springing and detents of positions is done in the ignition switch, not in the lock. That said... There are two things that could cause the problem you're having: a) The spring in the ignition switch is not working properly and you need to replace the switch. It's cheap and plentiful and easy to replace. You might even be able to do it without taking the whole lock assy off the steering column. The other possibility is that the lock assy is worn out and what is supposed to be a smooth easy rotation is catchy and notchy in certain positions. This is more difficult to fix and is more expensive. How does the key feel in the rest of the positions? Does it rotate smooth? Can you pull the key out in any positions other than "LOCK"? When you say you have to force it back to the "ON" position, is it a smooth rotation back to "ON", or does if feel like it's getting caught on something? BTW - Here's some of my experiences with the ignition switch assy. http://www.classiczcars.com/forums/thread44869.html and from that thread. The switch is in the lower left: I fixed all my locks and keyed them all the same, but I never went back and updated that thread. There should still be some info in there that can help though.

The hoses on the float bowls are part of the "anti-dieseling" system. When the engine is running, there's a solenoid valve that vents the float bowl chamber to atmosphere through the air cleaner. This means that when the engine is running, everything works the way you're used to seeing with the standard round tops. The trick is, however, when you turn the key off, that solenoid valve de-energizes and the float bowl vent is no longer connected to the air cleaner anymore, but is instead connected to the decaying manifold vacuum as the engine grinds to a halt. This negative pressure above the fuel in the float bowl prevents fuel from being pulled into the engine through the venturi and renders the carbs ineffective. This prevents dieseling after the key has been shut off. I'm not surprised... They look like they've got a good mix of features from both round and flat tops. They've got the round top nozzle adjustability and the independently controllable mixture on the idle circuit of the flat tops. Best of both worlds?

In theory, any changes that you make to the idle mixture and idle speed screws should have the same impact on each carb. The air that is metered by the mixture screw is supposed to be split evenly into the two carbs, and the idle air out from each carb is supposed to be the same as well. In theory at least. That said, if you crank both of those screws fully down, then your carbs should operate just like all the standard Z round top carbs. Use the high speed idle screw (I assume there is one of those) to simulate an idle circuit and sync and tune just like you would any round top. Then once that is done, you should be able to release the high speed idle screw and open up the idle speed screw instead. You will probably have to mess with the idle mixture to get it right at that point, but if everything else is working right, it should fall into place. The theory would be that you run a little rich at idle using the nozzle drop, and then lean it out again using with the idle mixture screw. What else? The anti-dieseling solenoid should have no effect as long as the key is in the "ON" position. If everything is working as intended, then you should be able to completely ignore the anti-dieseling stuff completely. Also, I'm traveling right now, and my internet access is spotty, but hopefully I'll have some access.