datx

Hello, I have a 79 310 that I have been working on-and-off for over a year. Thought I had everything running good but now it cuts out when I go above 45 mph. It is not consistent. Sometimes it will run good a little longer than others. Drop the speed back and it runs fine after a little recovery time at the lower speed. I replaced the fuel filter and even thought it may be a vacuum issue in the gas tank but I tried running with no gas cap (thinking that may help) but it does not. Any recommendations would be appreciated. I am no mechanic this car is my first automotive project. Is there an adjustment I should try on the carb? thanks

Well looks like it was the carb. I inspected all the vacuum lines and found nothing so pulled the carb again, cleaning it again. I did notice that even though I did have the carb tightened down that I may have been getting some leakage between the valve body assy and the plate. Once recleaned a reinstalled the carb using gasket sealer on the gaskets and that did the trick. Car is idling good now. Also car has not smoked since I drained some oil down from the full mark, thanks for all the suggestions it helped me learn a little more about my datsun.

Yes it looks like the yellow one. I did drain some of the oil this weekend (about 3/4 a quart) and it did stop smoking. The dipstick is reaching about 25% up from low mark referencing the gap from L to H. For my other vehicles I would call this low but if it works for this one so be it. I checked cylinder compression tonight and below are the results; cylinder 1 = 175 psi cylinder 2 = 175 psi cylinder 3 = 180 psi cylinder 4 = 180 psi Do these numbers seem correct? I have never checked compression before so let me make sure I did it right 1. warmed up engine 2. disconnected center distributor wire 3. removed all spark plugs 4. I did not tie open throttle plates because I did not want to remove the air box so I just put the accelerator to the floor 4. turned it over about 4 times 5. repeated for each cylinder. Was holding the accelerator to the floor sufficient? My wife helped me and messed up a could times and forgot to hold the accelerator down on a couple of the cylinders and they each read 150 psi when this happened. Lastly I did replace the spark plugs tonight and it does start better but not without gas so am I back to a carb issue? I removed and fully cleaned the carb when I first got the 310 and it was idling great now it will not stay running without some pedal to keep the rpm's up and idles rough before quiting when the pedal is released. One last observation I will note maybe this will give a clue to my current issue. Before this issue began when it was idling well (not smoking etc) I did notice that it would up and quit after running a while. I discovered that there was vacuum building in the gas tank as it ran and once it set for a while or I opened the gas tank to equilize the tank it would fire right and and start running again idling great. How that it idles rough I no longer have vacuum after running it for a while in the gas tank actually I have a little positive pressure in the tank?? Thanks in advance for any additional suggestions.

Thanks for some of the helpful suggestions. The datsun is yellow, it is a sedan with the A14 motor paired up to the 4 speed manual tranny. I have all the original owner documentation along with owners manual which specifies fluid capacities. When changing the oil I put in the 3-3/8 qt that the manual calls for with oil filter changeout. I checked the dipstick tonight and it is a LITTLE over the full mark but not by much - maybe its possible that I did not get all the old oil out since as listed earlier it started acting up for the first time when I was trying to warm up the oil for the changeout. I will try draining some oil out this weekend to see if this helps any. I checked the spark plugs and all looks well. Today I purchased a compression tester so I will check the compression this weekend and post the results to see it this is normal. I really would like getting this car back on the rode soon my son has just joined a travelling baseball team and we plan to have a lot of fun in this car traveling to games. thanks

Hey guys I'm new to the site and hoping someone can give me some advise on a B-310 issue I am having. First off a little description of my datsun. I finally was able to buy the first car I ever drove a 1979 datsun B-310. This was my Grandpa's car and I only drove it for a short time when I was 12 or so years old when we went to go feed cattle. He had bought the car from the orignal owner years before this and had repaired it following a wreck it had been involved in. He parked the car years ago (I estimate it set in a field for 15+ years) before my uncle who had inherited it final sold it to me after trying for years to purchase it from him. It had been parked due to a faulty slave cylinder (that's all). Once obtained I started tearing into it thinking it would not be to big a project to get running again - this is were I was wrong. You see this car only has 27,700 original miles on it and the car was under coated etc and amazing really has no rust issues (just a couple small holes in the passenger floor that will need small patches). So far here is what I have done to the car; drain old gas and flush gas tank with fresh gas, remove and clean carb, purchase new mech fuel pump, replace fuel hoses, replace slave cylinder, replace all original fluids - diff, trans, oil. Following this I have driven it some and it has 2 modes - 1. runs perfect idling etc 2. Barely runs at all, blue smoke comes out the exaust,etc. I cannot figure this issue out. The first time it happened I was warming up the engine to drain the old oil and all of a sudden after running fine for a while it went from running great to smoking and barely running when I kept the pedal down. I changed the original oil out noticed one of the spark plugs was loose and that seemed to fix the issue until tonight it will not even start without a lot of pedal and smokes like crazy (blue smoke) when I am able to keep it running - basically it will not even run now. Keep in mind I have had this car running quite a bit since the first incident and it did run fine. Is this some sort of timing issue? I am not sure where to look??