Anyone guess why I'm experiencing sputtering and uneven acelleration?
I added some oil to the carbs so the level is good but still has it.

_________________
Nov/70 late series one HLS3014777 Sunshine Yellow 919

Either fuel supply or ignition.

IGNITION:
Needs a new coil or
Vacuum advance not rotating the breaker plate or
Mechanical advance not pivoting outward or
Needs points reset or
Timing needs adjustment

FUEL:
One carb not delivering (clogged jet, stuck float) (I had tiny bits of rubber in hose) or
Fuel pump not delivering enough fuel or
Choke(s) stuck open (delivering too much fuel) or
That stupid winter/summer valve on the air cleaner neck has closed again, in spite of your best efforts to wire it open.

Just my guess.

Do you get black smoke out the back when it sputters?
My problem was my coil. Changed it and POOF! the sun came back out again. Even the best coil can fail after 5-8 years.

_________________
1970 240Z

Thanks Frank
I'll try a new coil.
It's a fairly new problem.
As usual too much stuff to check.

_________________
Nov/70 late series one HLS3014777 Sunshine Yellow 919

Sorry, couldn't be more specific at long-distance.

_________________
1970 240Z

It's either a spark or fuel problem. I would start with the Dizzy.

My car is doing the exact same thing. It gets progressively worse the longer it's driven to the point that it's studdering constantly. It started a couple weeks ago but haven't had time to check it out.

It has spark and gas in all 6 cylinders but I can't say it has it at all times. I got a coil coming in tomorrow so we'll see what happens. Also, my car is fuel injected.
Good luck!

How many miles do you guyZ have on your spark plugs?
Neither of you is trying to run those infernal Champions in a Z car, are you?

_________________
1970 240Z

I have newish (600ish miles) NGK BPS6-11 i think they're called. New wires as well.

You can tell a lot about what's happening in your engine by the color of your spark plugs after running it hard (or trying to). There are charts in the back of most manuals which give us a fair list of what to look for and what the colors mean.

Also, spark gap is vital to happy Z cars. Spending 10 minutes checking for proper (and consistent) plug gaps is a big step toward a happy engine. Also, if you find one (or three) plugs a different color than the others, it can indicate an issue needing attention. If I find that, I like to swap the plugs around to different cylinders and then check them again to see if I can decide what's happening to which cylinder(s). If one of my carbs is too rich, either the front 3 or rear 3 plugs will be black and wet.

And any time you get smoke out the tailpipe, that's telling you something. Black smoke shows too-rich fuel mixture (not all getting burned); blue smoke shows oil being burned in the combustion chamber along with your fuel; grey smoke shows faulty plugs not firing at every engine speed; white smoke (Gawd forbid) shows water or antifreeze being sucked into your combustion chambers along with your fuel.
You can run a paper towel around the inside of your tailpipe extension and see if it's wet with oil, sooty black or wet with coolant.

["It gets progressively worse the longer it's driven"] The longer you drive, the hotter a bad coil will become. The hotter they are, the worse they perform. I would start there.

_________________
1970 240Z

New Coil did not work but was definitely worth doing as my old coil looked like it was 40 years old. Time for more research!

Also, I did notice one spark plug of the six was much whiter than the others that were dark and wet looking.

They are supposed to be "light tea" colored if they are the correct heat range and everything else is set correctly. White means a very hot cylinder, usually from being too lean (fuel). But the other 5 contradict that, since dark and wet indicates too rich a mixture. Might you be running one plug which is a different heat range from the rest? You can try swapping that white plug into another cylinder for a day and see if it's either the cylinder or the plug itself which is too hot.

Can you check to ensure your choke is not ON without you knowing it, or that the Winter/Summer flap at the air intake isn't accidentally closed? Also, Fuelie cars have a "cold start" feature which acts like a choke and is supposed to shut itself off when the engine warms up. Because you said your car runs worse the longer you run it (the warmer it gets), that might be worth looking at.

Also, are you 100% confident you are using the spark plug heat range your manual calls for?

_________________
1970 240Z

Bump.

Surfer, what's your status?
BFG found rubber chunks in his fuel line and swapped out his entire secondary ignition system and says the car flies now.

Have you isolated any problem with yours? Car show is just around the corner.

_________________
1970 240Z

I topped off the oil in the carbs and that didn't fix it.
I bought straight 20 weight 3in1 made for electric motors.
I still haven't had time to swap the coil.
I plan on it today also pulling the wheel to check the multi switch for lights.
Where were the rubber chunks in the line?
I changed both fuel lines from the tank to the engine bay recently.
However I have a constant filter clogging problem.
45 years of crud in the tank.

Are you still off the grid?
Call me if you can for some questions.

_________________
Nov/70 late series one HLS3014777 Sunshine Yellow 919

"Where were the rubber chunks in the line?"

Mine were in my carburetor float bowls. They didn't float; they sank to the bottoms of the bowls and plugged up the jet intakes. As soon as I got them all out the fuel flowed smoothly and the car ran fine again.

But that was my first sputtering problem. My second happened three years later and was the coil.

Not sure if I still have your number. Message it to me.

_________________
1970 240Z

Well I finally got my electronic ignition and coil. They are made by Pertronix. The install was very simple and anyone can do it. Here's what the new stuff looks like.
Of course it wouldn't start the first time. I put the positive lead on the negative terminal.
Swapped it to the right location and started right up! I took it for a shakedown run and the sputtering had disappeared. Frank you were right about replacing the coil.

_________________
Nov/70 late series one HLS3014777 Sunshine Yellow 919