I have a problem with my 72 240z. Say the car is in third gear on a very slight grade upward, the rpms are slightly below 2500 or at 2500 and gas is given; the car chokes itself. There is a lurch like the engine is lacking fuel.

Is this the carbs? A problem with compression? not really sure. My dad thinks its the carbs. Could be.

thanks

Your Dad could be correct. One thing I've learned is to ALWAYS listen to your Dad. So make him happy and make sure your carbs are getting enough fuel. Replace the fuel filter. Take apart your bowls and make sure they are adjusted correctly. Make sure that all the fuel is flowing at it's full potential. If your car still stalls under load then check your ignition timing. But most likely your Dad is correct.

What oil are you using in the carbs ? Try some 20wt and see if this clears up the stumble . Have you ballanced the carbs and checked the mixture? If you are running lean this could be the trouble another thing is the vacume advance check that this will also cause what you are describing .

Listen to your father. Also consider a few other conditions. I have a 76 BMW 2002 (and yes, a 1970 240z in reparations) and when the 02 runs a little rough at 2500-3000 on a flat highway, I know it's time to replace points, condensor, rotor and cap, at least clean the plugs (or might as well replace them), check and routinely replace vacumn hoses and air filter, and do check carb adjustments and timing. I keep a supply of vacumn hoses of various sizes at all times. Also check the general condition of engine wiring, and specific items such and alternator and coil. Another problem area can be the mechanical fuel pump cam or lever, pump diaphragm, hoses etc. I would switch to an electric fuel pump if you haven't already.

So, assuming everything is in top condition, rebuild your carbs and it should run great. If the pistons are dirty they will stick and the mixture will be incorrect while all static adjustments are dead-on. Good luck.

Jim

All as stated above, and in checking the carbs- check the float level setting specifically. That could itself be causing fuel starvation on one of the carbs.

thanks for the help. My dad rebuit the carbs once before. That was way back! I think in the up comming week we may rebuild them.

Just wondering: what is the correct amount of oil for the carbs?

Dunno the exact volume, but they are self-adjusting. Just top them off, then lift the needle assembly as high as it goes- any excess will spill out and be burned up.

Just wondering: what is the correct amount of oil for the carbs?

I thought there were indicator marks on the dipsticks and you dont want to over fill them. Picture attached.

Chris

I checked the level of the oil, it seems just right. Maybe about two months ago new oil was put in, and i am not sure if the weight is correct. Can oil go bad just sitting in a container? Because the can for the oil I used looked old

and it did not say the weight.

thanks for the help

What kind of oil are you using? Some people use ATF or straight 20wt. Other's use different weights depending on application. And you should fill to the line indicated on the plunger (dipstick). If you over fill don't worry it will spill out into the intake and be burnt off.