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First drive in the Z, Backfiring and sputtering.


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First, I don't claim to be an expert here by any means. But, I did have the exact same problem when I bought my 71 which had been sitting at least five years. It ran great on new plugs but would foul them in about 5 to 10 miles start backfiring and lose power. I bought the carb tape from Z therapy and, even though I had no idea what I was doing, managed to clean the carbs out, set the floats and needles correctly and get the chokes working properly. About four hours later, the difference was amazing. The guys at Z therapy sent me a couple float bowl gaskets with the tape and were great help. My advice is to buy the videos and go through the carbs.

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Ok, so what would be a good way to check your theory? Bypass the fuel in the tank and hook the fuel line straight into a 1 gallon tank. That would not tell me if the carbs are clogged though.

Bad fuel would not really explain fouled out plugs after 5 miles. Im sure there must be more to it.

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Pressedsteel, I think your most likely correct. I can almost guarntee that if i was to go buy some more plugs it would run great for a little bit, untill they fouled out again. Im going to order the carb video ASAP.

Im suspecting the carbs even more now after this discovery. Check out the zip tie in the picture and the missing adjuster screw. That can't be good. :surprised

post-7323-14150794504629_thumb.jpg

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Carb adjust could very well be part of it, but why would you want to mess with the carbs before making sure that they weren't going to get screwed up again by old jellied fuel and crud from the tank? Step, by step. It's highly unlikely that there is just one problem needing to be addressed.

After confirming that the fuel supply is good (volume and clean) I'd check the filters at the carbs first, the one on the passengerside second (I'd cut it open and examine it) You can get a new Fram #G3359 fuel filter for about $4 almost anywhere. Do (or have it done) a complete tune-up on the engine and carbs.

I wouldn't suggest driving the car with an alternate, 1 gal can of fuel.

Getting a car that has sat for 5 years to operate safely and properly isn't a matter of simply changing filters and driving away. You will likely have several issues resulting from it sitting idle for such a long time to deal with in the near future. Brakes, cooling system, fuel tank are just a few of the possible[/] problem areas you may need to address.

Do yourself a favor and check (or have them checked) the rear brakes (cylinders) for safe abd proper operation. They often go bad when a car sits for a long time. You don't want to find they are bad at the moment you need them the most.

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FWIW, the missing screw doesn't have anything to do with setting the fuel mixture, it's related to balancing the operation of one carb against the operation of the other carb.

That's correct, except that it is the balance screw for part of the system that your car apparently has had removed. The Air Pump for the "smog" system has been removed from your car, and the vacuum pot that prevents the carbs from "slamming shut" has been removed. This is where it hooks up to. The screw you are missing is to balance the carbs upon deceleration. If you were to cut that zip-tie you'd note that the linkage will just flip flop around and do nothing.

As far as determining that the vacuum advance system in the dizzy is still ok, look well underneath the points plate. If you see a ball bearing or two floating around in there, then it is shot. I'm not sure that 1/8" of travel is sufficient to consider it functioning well.

I'm of the opinion that you should try the LEAST intrusive remedies first. That means that you should check all the items that do not require massive disassembly, adjustment or changes, BEFORE you go doing those changes.

Remember, the car did RUN, as such, I don't think you need to disassemble the whole thing only to discover it's a bad plug wire, plug, filter, or adjustment. The things that everyone has been mentioning are the type of items that they've had experience with, and as such are the first things that come to mind, exactly as Zedrally points out.

The gas problem is something you should have done something about. However, by now it would be hard to drain and clean without having a very hazardous situation on your hands. If you do decide to drain the tank, be very careful as 15 gallons of gas is not something you just want sloshing around on your driveway. If you do drain the tank, then decidedly change the fuel filters even if you "just" changed them.

2¢

Enrique

post-1490-14150794505141_thumb.jpg

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As far as determining that the vacuum advance system in the dizzy is still ok, look well underneath the points plate. If you see a ball bearing or two floating around in there, then it is shot. I'm not sure that 1/8" of travel is sufficient to consider it functioning well.

My new "Nissan OEM Rebuilt" Distributor has at least 1/4" to 5/16" of movement in the Vac Advance.

http://www.classiczcars.com/forums/showthread.php?p=108599&posted=1#post108599

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A good investment would be a shop manual for the car, pull the cap and rotor off the distributor and with a screw drive <flat head> open up the points and see if they are pitted at all or have uneven wear or white areas around the edges. You might need a flash light to get a good view. To adjust them there are two ajustment screws one right below and one above , but there are 3 total there. With the raised side of the distributor shaft hitting the points you can adjust the gap, I think its .0018-.0022 , but you have to have it on the top of the distributor lobe for lack of a better term. If you need pics I can send ? I do better with hand on than descriptions. I would also try running the car with the gallon gas tank next to it. I bought like 6-7 feet of fuel line and that how i diagnosed my to have crap in the tank. After having the tank cleaned no more prob and my car sat for 2 years and i did what you did , added fresh fuel to a little bad. If you might have a funky gas smell if you keep it in the garage its varnish like , I would point towards the tank. But try it with the stand alone fuel can. But also you might have clogged the fuel filter as well as the inline filter in the carbs with the junk can can be brought up from the tank from sitting. Good Luck

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Thanks for the help!

I just checked out the points, they seem to be in check and pretty clean. The hardest part is to get the largest part of the distrubutor lobe to line up. Any tips on how to do that? Other than jacking the car and turning the crank pulley.

"I think its .0018-.0022"

Is that correct? That is what i set it too. I just wanna make sure you did not mean .018-.022

Im going to run a compression check next.

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