commplexone

It was originally an automatic car but has a fresh motor and trans in it now to make it a manual. Car was wired for the dual point originally so i put the dual point in it rather than the beat up single point it had when i got it.

Hi guys, I seem to be running into all kinds of problems while trying to work out all the bugs in the Z i just bought. With the advice of many here i have made a ton of improvement. Car has been running good but i have noticed something yesterday and today. At idle i can feel the car "missing" or making a subtle popping noise and i notice that the Tach jumps in sync with the popping. Off of idle the car will hesitate badly unless i rev the engine enough to get her going. I also noticed that this popping will occur sometimes while driving almost like its missing a cylinder or something. I am leaning towards some type of ingition problem since i have correctly rebuilt and rejeted my weber carbs. I recently put new plugs, points and plug wires on the car as well. I dont know what it is really but any suggestions would help a ton. here is the shake down of my car by the way.... 1972 240z with an L24 and dual weber dgv carbs. I also updated to a brand new nissan dual point dizzy like three months ago. On a side note, i am wondering if a new coil and pertronix updrade would help with this problem any?

Sorry i forgot to include some details. My car is a 1972 240z and it has a semi built L24 in it. I was just wondering how they were set up originally so i can try to duplicate it as close as possible.

I am now certain that the person who owned my Z before me messed up on the fuel line installation. He ran all 1/4 inch rubber hose and the return line is plumbed up back into the filler some strange way. Anyways, i am going to drop my tank soon and do this all over. Can anybody here please diagram or explain to me how to run proper fuel lines?

Thanks again Beandip, Spoke with him and he gave me very good advice to correct this problem.

After the post here and information i have received from others i have decided to just keep my vacuum advance hooked up. I do have a question tho... The vacuum advance from my distributor is hooked up directly to the balance tube. This is the way it was hooked up when i purchased the Z. It currently has dual 32/36 Dgv carb's on it and i was wondering if this vacuum advance placement is right or not. Should i be sending the vacuum advance directly to the carbs or is the balance tube the correct set up?

Just curious, Has anybody mounted a small electric fuel pump in the engine compartment instead of under the car or along the frame somewhere?

I installed the oem mechanical replacement just to see if i was having a pump issue. I just got off the phone with top end performance and they said my lobe might be worn that drives the pump so i should definately just bite the bullet and go electric.

Only thing I did was change the oil, new thermostat, change coolant, new distributor, valve job, new battery, all new fuel lines except for return line, and add a tachometer prior to this happening. The car worked fine for a month or so while i performed all of the above and only started acting up randomly on the freeway this past friday night. When i noticed the problem i took both carb's off, completely rebuilt them (i mean completely) and put them back on with new gaskets. When i went to test drive the car after putting the carb's back on the problem was still happening. This morning i put in a brand new fuel pump and it is still happening. I am stumped because this car was driving great and then all of a sudden this happened. I have done nothing mechanical that would have caused it. I am running a fuel rail and there is a brand new clear fuel filter so i can see whats going on. Plenty of gas is being given to the car cause the filter is always full. Like i said i replaced all fuel lines but the return line. The way it is set up (dont have any pictures) is from the tank it goes to the filter. After the filter to the pump and from the pump to the fuel rail. Carb number one gets fed first and has no problem. Carb number two gets fed second and is the trouble maker. After carb number two fuel is sent to the return line. I know that that carb isnt spitting gas at high rpms because when the problem happens i get out with the car running and manually pump the carbs. Number one works fine and number two shoots nothing. If i turn the car off for a few minutes, then restart it, both carbs will work fine until i get up to around 4000 rpms and it happens again. I do have a few questions tho... 1. Can i get around the fuel rail and just go straight from pump to carb to carb? 2. What would happen if i was to pinch the return line off completely and just run straight to the carbs? I really appreciate all of your suggestions by the way. If i didnt have a place to talk about this stuff i would be in a world of hurt. Thanks so much guys.

Beandip, do you have any advice for an electric fuel pump that i can purchase from an auto parts store or a speed shop? I would like to just grab one without having to do much looking around.

I have dual weber dgv5a's set up in my 72 240 and a problem has developed. Let me first note that i have rebuilt both carb's since discovering the problem and the same thing is happening so the rebuild did nothing for it. Anyways, here goes... when my car is cold and or off the carbs work great. When my car warms up my probelm starts, particularly between 3500 and 4000 rpm's. When my car is at high rpm's whether it is cruising down the freeway or when i really jump on it (80-90mph) my secondary carb just plain stops spitting fuel. Carbs work fine when i stop, shut it off, get out and then go check but when driving i have the problem. Keep in mind the primary carb (the one that gets fed first) has no problem but the secondary gets starved completely. When i rebuilt i checked all jets and everything was gutted to be completely cleaned. This is really confusing me because i have no idea what could be causing me to loose all fuel delivery in carb number two at higher rpm's. Please help, any and all advice is greatly appreciated. P.S. I have had this car for a little over a month and this just started happening a few days ago.

I have noticed that on alot of the performance Z's i have seen recently that the vacuum advance from the distributor to the balance tube has been plugged and not used at all. What are the benefits of this and why do some people do it?

My Z is now down to bare metal inside and that really stick awful jute fiber board stuff. Does anybody have any idea on how to get that garbage out of my car so i can start on the interior?

Thank you very much for your help. I really appreciate it. After listening to what you said i put two and two together to realize exactly what you said is correct. I will get that all taken care of asap. I was having a hard time with understanding cause my car has the dual weber dgv set up and the pcv was blocked on it making it hard to see. I understand cars but i dont know much of anything about datsuns so your help is really appreciated.

Yes it is a 72 240 and it is carbureted. I have noticed a very distinct fume smell in the cockpit as well. I feel dumb for saying this but can you please explain to me what you mean by connected to the PCV port on the balance tube?

The Z i purchased has the k&n breather filters on the valve cover and on the engine block. I noticed that they both emit smoke when under a load and are very oil soaked. To me this seems like a mess and i dont really like the idea too much. My question is, can i just run some rubber hose from the two into some sort of drain bucket in a hidden location or just run hose from one to the other to block it off completely? Also, the breather tube from the engine block has another smaller spout coming of for what looks like some sort of vacuum hose or something. I dont really like the idea of having open spouts and oil dripping on my motor so can anybody please elaborate on clever ideas to clean this system up a little bit? Maybe even a photo or two of others set ups would be great help as well. Thanks again in advance, i am just a newbie trying to learn the ropes.

I just purchased a 240z that is in good shape but the previous owner had it tuned really weird. It needed a new distributor so i dropped one in and cleaned the carbs up really well. It has the regular L24 motor but has been beefed up a little with dual webber dgv carbs and it runs like garbage. The timing is definately tweaked. I dont have a light and wont be getting one for a few weeks but does anybody have a suggestion on how to time it by ear? Any tips and tricks would help greatly. Thanks in advance!

I have replaced the distributor in my older mopar's before but never in a z. I need to put a new distributor in my 1972 240z and have located a brand new oem single point distributor in my area. Can i run this distributor for a few weeks until i convert it to electric with a pertronix kit? If yes, any advice in how to change the distributor properly and gap the point would be greatly appreciated. Thanks so much for your information in advance.

I just purchased a 72 240z project car that runs well. The only real problem with the interior for me is that the tach doesnt work. It wont work unless you hold the ignition key about 1/8th of an inch to the right, then all of a sudden it pops on. Does anybody have any advice on how to fix this problem? Its so weird, i can be cruising down the street and want to know what i am taching so i just turn the key to the right a bit and boom it comes on.