5 Star Rising

Here is a picture of one of the needles that was in my car. It has a "Z" on the side. The other needle on the left in the picture is out of a 72 240z that I got from a friend it was not in my carbs but just used as a reference. Does the one on the right look like a racing needle? I have no idea what to look for in comparison.

Thanks Inline. That is some good info. I actually replaced the distributor and have the same issue. The shaft on the old distributor had a ton of play and the vacuum advance diaphragm was shot. So I got a rebuilt unit from Autozone, the new shaft was tight and the diaphragm in the vacuum advance acually held vacuum pressure with a vacuum pump how ever the advance mechanism did not move very much even applying a bunch of pressure. I cant see the engine producing as much vacuum as I pumped in that thing, so the advance probably does not work too well with the reman unit. However with the new distributor and electronic ignition excluding the points and condenser, I still have the issue. I tried the timing in mutiple positions btdc and extremly advanced and had the same issue. I wish I had a spare set of good running carbs to bolt on and see if it ran different.

I have a old school air/fuel mix machine with a stinger that I got at a garage sale a few years ago. I hooked it up last year and it said the carbs were a bit rich at idle, I'm not sure how accurate that machine is. I watched that z therapy video 3 or 4 times already and followed it. But still getting the same result. This isn't my first Z, and I never had a issue like this before. Going to check the needles this weekend. Wondering why I can clean up the miss when I pull the choke back. Also going to watch that video again..... this is getting old.

I went through the ignition system already, timing, new distributor, new coil, got rid of the points, went electronic ignition, same issue. How can I make the carbs run rich with the choke open all the way? Seems like it is not getting enough fuel. Runs better when I choke it and cut the air consumtion in half thus balancing the air fuel mixture better. As soon as I open the choke all the way it seems like the carbs are getting way more air than fuel. Would raising the float levels so that the fuel almost pours out the top of the nozzles help richen the mixture? It backfires out of both carbs when I Rev it and the choke is fully open. Doesn't really back fire when I pull the choke back a bit. I have both carbs set to maximum rich settings and it doesnt seem like it is enough fuel.

The car never ran right, i used cans of carb cleaner to find small vacuum leaks never found any the car ran the same. Tonight I started the car after months, it idled good and reved up good and smooth with the choke pulled 3/4 of the way back, as soon as the car fully warmed up I open up the choke all the way and reved the car. I got the back fire out of the carbs and that miss. Im thinking maybe the carbs are just super lean even though I have the adjustments on the bottom of each carb set to the richest possible setting maxed out . Maybe it's still not enough fuel. Is there a way to make these carbs even more rich? Like maybe adjusting the float levels more?

Good read. Looks like he had similar issues. Yeah when you get like 30 minutes a week to work on your car you want to dive into it with a plan in hopes that you can solve the issue. Hoping to nail the issue before summer. Hardest part is trying to figure out what the PO has done to this car. I see evidence of mods. Had a wideband, oil cooler, wide open exhaust, the car has a little lope, could have a different cam in it, oversized pistons, racing needles. Trying to set everything back to factory as much as possible if possible but depending on what he did I may not be able to.

Still haven't had time to pull my carbs, but do you think that because one of the pistons has more resistance going up than the other carb that it may be the issue?

One of the Pistons moves up slower than the other like it has more resistance but when you let off the piston they both fall about the same speed. I have a constant Miss or flutter throughout the RPM range I also adjusted the carbs to Max rich settings but still get the backfire. I am using ATF fluid for the oil. Last weekend I got some needles and the complete bottom seat assemly off a 72 240 that was completely rusted in rotted out including the carbs or at least they looked pretty beat. I have yet to take my carbs out and swap the needles and seats but at least now I have something to try. And now you got me thinking about the Pistons.

Any one else experience this issue with the door gap? Are there adjustments? Thanks

The passenger door fits fine and lines up but this different driver door that someone put on is weird. Wonder if the latch can be adjusted out farther somehow so the door doesn't sit so far in the door jam.

Got this car a while ago, the drivers door fits weird and has a gap near the fender also seems like it sits farther inside the door jam. I have not tried to adjust the door or the fender to close the gap yet. Is there a adjustment to align doors or is this the wrong door for my car. My car was originally Blue but this door is Orange like someone has changed it. The inner part of the door looks like a 240z door compared to a 260 or 280 as far as the sheet metal cut out holes.

Feels like I get to work on my Datsun every other month. Here we go again still dealing with the same issue. Not knowing the history of this car kind of sucks but the latest thing that I found may be the cause is that the prior owner possibly installed race needles in the SUs.. I cannot get rid of the miss, or tune these carburetors properly . how can I tell if I have race needles? And if I do, where can I get a set of factory needles that don't cost an arm and a leg?

It looks like the prior owner had a wideband installed but he took it out. The probe and wire is still mounted to the header. The needles that are in the carbs are large (fat) compared to a cheap set I ordered and returned a few months back, didn't have any other needles to compare them to, but they were bigger than the needles that came in the cheap carb rebuild kit and the needle valves were bigger in my carbs than the ones that came in the cheap kit too.

So here is a super short clip of my car running. Sounds like it's running lean with those backfires. Its not smooth and responsive when driving. I get a miss in the mid rpms also. Does this sound carb related? 240z backfire_001.mp4

Apparently that video upload failed. 40 mins so far trying to upload

240z

Checking back in. For the last few months I have been building a engine on my 71 Chevelle, It is finally done and runs amazing.. I am ready to start trying to figure out this issue with the 240z again running like crap and sometimes backfiring. Technically I never rebuilt the Su's because the kit they sent me was wrong and it was of cheap quality. I cleaned the carbs, put back all the same parts and set the float levels. I'm wondering if the guy before me put race needles in these carbs or something to make them not tune correctly. Been wanting to slap another set of Su's on the car and see if the carb's are my main issue but cant seem to find a good set local and they are a grip $$$ online just for testing purposes. I will see about getting a video up.

Yes 1,5,3,6,2,4.. I checked the firing order a few times. Yeah series 1 pointer is different than other Zs I have had in the past. I have a full on fuel pressure kit. I would have to mention when I got the car it had an electric FP and I had the same issues, I switched over to a manual pump and have the same issues as well. If you take one of the fuel lines off the carb and put it in a bucket and turn the motor it gets a solid stream of fuel coming out. I had purchased a 240z Su rebuild kit off the Internet that said 70-73. But when I opened it up it had smaller jet needles and needle valves than what was on my series 1. I ended up returning the kit and the guy said maybe it was for late 71 to 73. He did not have another kit to fit my 4 bolts. Not to mention the parts in that kit were super cheap and I felt like they would fail anyway even if he had the correct kit so I stuck with what I had. I remember having a problem setting my float levels though. In the video it shows turning the float assemblies upside down and setting the float levels that way, but I noticed when doing that the weight of the dry float would depress the needle valve slightly thus causing a inaccurate setting.

I finally had some spare time today. I started from the beginning tuning the carbs, I found that I had them set very lean, one of them I had turned all the way in. I started with 2 1/2 turns down and went from the there, balanced them with a air flow meter,set the high rpm adjustment. The backfiring went away and I got the car running good in the driveway like I had did before when I had found 2 spark plug wires swapped. So for the first time I took the car out for a test drive. I noticed the car will stumble pretty bad around 3k and it will backfire out the tail pipe. It's like I can't get the rpm range to Rev up smooth under a load, it stumbles, misses, and backfires. I was able to pull over a few times and richen and lean the carbs to try to find a sweetspot. I could notice a difference each time I messed with the carbs, sometimes the backfire would be gone but the stumble would be worse, sometimes it would be more snappy and smooth but would backfire a ton. I'm wondering if these carbs are causing the issues. Maybe I need to really go through them again and buy a good rebuild kit. I'm using the same parts that came with my carbs because the crap that came in the rebuild kit didn't fit my 4 bolt SUs, so I just ended up basically cleaning the carbs inside and setting the float levels. Also for piece of mind I tried a new Ignition switch, Cap and rotor, and it didn't make a difference. Really wish i had a spare set of good SUs to slap on and see if the car ran good, then I would know if there was something screwed up with these 4 bolt carbs.

Here's a few pics Seattle.

Oh, I forgot to add there is no air cleaners on the carbs at the moment, not sure if that makes a difference. I watched the JUST SUs video and I don't think he had air cleaners on the carbs while adjusting them.

So I'm still having the backfire issues through the carbs and tail pipe upon reving the engine and there is a small miss at idle. I have been running in circles on this one and I know it's probably me leaving something out or not going in order to troubleshoot this correctly. There has been multiple time where I "thought" I fixed the problem but it seems it's always there. Tonight I used the advice of checking the choke system. I found that the front carb jet nozzle was stuck it did not want to spring back up into the carb, I thought for sure this must be the problem, I adjusted and bent the metal arm slightly and now it springs back up into place. But i still have the backfiring issue. I set the timing again,adjusted the idle on the carbs, and balanced them using the air flow meter, runs somewhat smooth at idle but when reving i get the backfire. Is there another way the choke operation can be sticking or out of adjustment? I'm starting to second guess all the work I did prior, like did I build the carbs right? I remember adjusting the floats a little more on one carb so that I could see a pool of fuel sitting slightly below the top of the jet nozzzle to match the other carb, I hope that was ok to do. I remember checking the compression in the car and it looked good but 1 of the cylinders spark plug was white when the others were a little oily. Even if the compression is good, could I have some kind of valve issue? I still did not bypass the ignition system and see if the car ran better without the signal going through all that old wiring. Could there be a defective new distributor cap?,could there still be a vacuum leak? Could there be a valve issue, could I have a faulty set of SUs that I didnt build right? Could the prior owner have added some after market mechanical parts like a cam? All these questions have been going through my mind. Sucky, just want to drive this thing for the first time.. blah

I'm liking this music,car show feel with a message. Yeah the reason I let the car sit for a few weeks maybe a month is because I was working on the interior, had to locate a set of seats so I could go test drive the car, I found a set a prestine late 260z seats locally for 50 bucks and couldnt pass up the deal so slapped some 240 brackets on them and put them in, I can get some correct series 1 seats later if I go that route. Had the Vinyls and carpet out,the console removed and newer aftermarket plug n play fuse panel unbolted and pulled to the side. After putting every thing back in place and getting excited to take my car on its first test drive I fired it up to back it out of the garage and it ran like crap again and back fired, that's why I was getting ideas of electrical issues since I had my hands in the wiring under the dash. The prior owner has wires twisted together with house wiring Wire Nuts I think mainly for the stereo but could be some other funky connections some where since he ran his own wires for the headlights haha. Here is another odd thing I recall happening last year. One time I started the car and it would only keep running if I held the key in the on position I didn't hear the starter still engaged while holding it like that, but that was the only way it would get power and stay running, also the tach was bouncing all over the place. I remember it being late at night in the garage so I fumbled with ignition switch turning it back and fourth,sprayed some wd40 cause the key was kinda getting stuck also, and that seemed to help the key but didn't doing anything to the switch I doubt and still had the starting issue. Then being late, I think went over to the Relay under the glove box (right kick panel area) and cleaned the terminals with wd40 and banged on the side of the relay a few times haha. Then I went to the Balast Resistor and cleaned the terminals and went to start the car and it started right up and stayed running like before,not sure if the relay or balast resistor was causing the issue but it has never done that again, it got me thinking if maybe there was still an issue with one of those components causing the backfiring issue, so the other day I changed out the balast resistor and added a pertronix ignitor and 3 ohm coil, and the car still runs like crap,so i know it's not the balast. I was thinking maybe the ignition is getting a weak or intermittent signal some how. Maybe the 46 year old ign relay is going out or bad ignition switch. Definitely a headache. Thanks HuD I will check the choke as well. Is there a way to bypass the black/white wire going to the + coil from the tach? Was thinking about bypassing all the electrical components if possible and have the engine run by its self as if it was on a test engine stand.

I did put new gas,full tune up,set timing,removed/cleaned/adjusted/rebuilt/set float levels on carbs, Checked firing order, Compression check,checked for vacuum leaks, I wanted to move to an igniter regardless if any of those components were bad for bigger spark and easier cold starts,replaced worn distributor, I found the prior owner had his way with the wiring and was questioning other possibilities in the electrical system that could affect this missing type symptom. Thanks for proper definition of "spudder" I can now go about my day knowing the forum police lent a helping hand haha. smh