Ok So i just rebuilt my 1971 Datsun240z with all new mechanics and it runs well but everyday i go and start it it takes a while for it to start. I have to usually hold the gas pedal down to give it some gas to get going. Once it is started it runs well. What do i gotta do to get it to go at the first turn of the key?

After it has been running for a while and you turn it off does it still do the same thing? It sounds like a cold start valve or something. I have not addressed it on my '73. She does that after it has sit for over 8 hours, otherwise she starts right up. I did not think it was that big of a deal.

A 1971 Z with SU's will not have a cold start valve. Are the chokes working? What shape are the carbs in? Did you rebuild them to?

Need more info here.

Jim

Does a '73 have a cold start valve? Mine does the same thing

Yes I rebuilt the carbs and the chokes work. After I get it started and it has been running and turn it off it will start right up again. Its just the first time after it has been sitting around 8 hours or so.

So when you move the choke lever in the car the fuel nozzles under the carbs drop down some?

Putting your foot on the "foot feed" (old timey term) does nothing to feed gas during the starting process.

another thought.... in the relaxed position is there a lot of slack in the cables? May be nothing more than just not getting the nozzles far enough down to richen things up enough to light that bad boy off.

If things are set on the lean side this will be a bigger issue....

When you pull the choke lever back all the way and turn the engine over it should start after about two or three revolutions . Just as soon as it catches push the choke lever part way forward and keep the idle at about 1000 rpm. Once he temp gauge needle is off the cold peg , push the choke lever all the way forward . This is a normal starting procedure for a SU equipped engine. If you haven't connected the choke cables this is your problem. Holding the gas peddle to the floor has no effect in attempting to starting the engine . SUs have no accelerator pump to squirt gas into the intake like other carbs . The choke does this by lowering the nozzle also if you are using thin oil in the dampeners of the carbs this will compound what you are experiencing . 20w oil in the dampeners is preferred 10w 30 is a second choice. As for rclayton the '73 has different cars , flat tops, and I am not familiar with them , I removed them as soon as I bought my Z , and got her home . Gary:rambo:

Yes I have replaced the flat tops with the SU's, but I do have to turn the engine over for about 10 sec. in the morning, or whenever the car has been sitting for a while (about 6 hours), I guess I need to look at replaceing the choke cables.

Hi Guys:

The L24's in the 240-Z's have always be "cold natured". When they were brand new - starting from cold (anything below 70 degrees is cold to them)... it took several seconds of cranking to catch and start.

As the cars age - the mechanical fuel pumps loose a little efficiency.. and it takes longer for them to suck the gas back into the fuel lines - then push it to the carb.s. The longer the car sits without being started - the longer it takes the first time to start. If you are in a colder area of the US/Canada... in the Fall and Winter months... it can easily take 5 to 10 seconds of cranking when the temp's are below 60 degrees.

The efficiency of the battery and the battery terminal connections will also cause delayed starting. Make certain that your battery terminals, cables and connections at the starter are CLEAN and TIGHT.

Fuel Injected Z's and all newer cars - maintain fuel pressure in the lines - atomize the fuel more completely via high pressure rather than high temp.'s - and meter the air/fuel mixtures with far more precision - so they "instant start" for the most part - don't expect an L24 with carb's to do that.

Once everything is warmed up - the L24's should fire on the first couple of cranks..

FWIW,

Carl B.

I think Carl nailed it. My '71 is in excellent condition. If it's been sitting more than 4-5 hours, it takes 5-10 seconds for it to fire. Seems to be totally normal to me.

ditto.....cold starts on my 72 take a bit......i was told this was normal. even sitting in the sun for a while helps mine on chilly mornings. sometimes i roll it out of the garage to sit in the sun for a while before turning it over. like someone said about 70 degrees or over and it fires up way faster.