Starting the Car ( Su Carbs)

[DeesZ]

I'm in Pennsylvania and it can get pretty cold here. Longer starts on cold days are normal in my routine. My '72 is like that now and my new '72 back in the day was exactly the same right out of the showroom. Cold weather is not the friend of the L24, and a good battery is imperative if you want to drive.

[beandip]

It seems that drivers that are used to injection are intimitaded with the use of the choke. As if it was something detrimental to the engine. Just look at the choke as the cold start is for injection . The difference is you are the computer that turns it on and off. The choke will not hurt the engine it mearly richens the fuel mixture so the engine will start and run when cold. Cold is lower than 70 degrees . Gary

[kenz240z]

Are the valves adjusted properly? Are the points gapped properly? Have you set the timing? Are the floats in the carbs set properly? Are the fuel nozzles properly centered? If not, the fuel needle may stick and prevent the piston from dropping all the way. Did you remove/replace the needles when rebuilding the carbs? If so, did you reinstall the needles correctly? Is the choke pull-off set properly? With the choke lever pulled all the way back, the fuel nozzle on each carb should drop about 1/4" AND the throttle valve should be opened slightly (around 0.025" iirc). Consult the FSM for all the carb adjustments (if you don't have a FSM, get one).

I have '71 round top SU's on my '73. It will start on the first turn of the key after about 10 seconds of cranking.

[beandip]

hold it kensz , he may just need to use his choke when the engine is not warmed . We don't need to tighten the lugnuts because the wipers are not working properly. Gary

[kenz240z]

Gary, I agree that proper use of the choke may be all that is needed for Keith to get his Z to start right up. Many of the items I asked about would affect the performance of the engine while driving, too, not just starting the engine.

Even so, the things I mentioned about float level, fuel nozzle/needle mis-alignment and choke pull off could be contributing to hard starting. Once warmed up, the problem might not be as noticeable. It's possible that his engine is running too rich/too lean due to a problem with the carbs, yet overall driveability might not be too aversely affected.

Keith mentioned that he rebuilt the carbs, so I feel these are all valid suggestions for things to double check, especially since I'm not there when he starts it in the morning, and I'm not there to experience how well (or poor) the engine runs at normal operating temperature. The mechanic in me can't resist the urge to help troubleshoot the problem, even though I'm more than a holler down the road from Keith...

And with that, I thought of another thing to check, although it would affect the carb when the choke is off.

Keith, when you rebuilt the carbs what did you use for the fuel line that connects the float bowl to the fuel nozzle? The carb kits I purchased recenlty came with a nice, braided piece of fuel line. Neat looking, but not as flexible as the original line, and can contribute to the fuel nozzle binding in the bottom of the carb so that when you push the choke lever forward, the fuel nozzle(s) won't pull back up into the carb. This will cause the carb to run rich.

[240Z-Fan]

Kenny,

I appreciate all the suggestions too. My 73 with rod top SU's is harder to start than Z's I have previously owned. The choke definitely works but the car is still very cold blooded.

Your comments have me thinking I can get the car to start much better than it does. (Granted, I only drive it a few times a year.)

One more suggestion to improve starting: A reduction gear starter from a 280ZX will spin the engine quicker than the original starter and should (help) start the car noticeably quicker.

My new belated New Years resolution is to improve the Z's cold start-ability.

Thanks!

Al

[Bruce Palmer]

Kcoke,

What if anything have you found to be the solution to your dilemma?

[wfl_colorado]

I am in Colorado, have a 73 w/ 72 SU's and have the same issue. Full choke and crank it. Then is seems to take forever to get it to warm up, but when it does, look out. After it is work, it starts right away.

Bill

[kenz240z]

Bill, if you and your Z are ever up in the Berthoud area, give me a shout. I'd be glad to help you get your Z to start easier.

[wfl_colorado]

Kenny,

I would love to talk to you some time. I need an overall tuneup as I bought the car about a year ago and swapped carbs, but haven't done much else. Need to check valves, points, plugs, etc.

I am hoping that all helps a bit, but am looking forward to summer. It also needs a paint job, but don't want to break the bank. Would also like to look into the urethane bushing replacement as well, as I think it has all the orginal bushing on it still.

Bill

[240ZX]

Yep, these babies are cold blooded and starting does take a bit of cranking. The procedure I subscribe to for starting is as follows. (I have an electric fuel pump only and I have converted to electronic ign) (1) Pull the choke all the way back. (2) Crank the engine over a couple of rotation and then turn the key to off. (3) Crank the engine again and it fires every time. (4) And as was mentioned by Beandip, push the choke forward to achieve and idle rpm of approximately 1000 rpm and let her warm up.

I believe it take a period of time for the fuel/air mixture to get into the cylinders, when it's been sitting for long period of time....hence the cranking exercise! Just my 2 cents worth!

Tom

[DeesZ]

240ZX, I agree with you. I have discovered that this winter as well; the pause in cranking does really help the starting process. I have a couple gear reduction starters out in the garage from previous projects, so I think I'll test one and install it too.