240z ignition timing carb sync NEED HELP!!!

[greylandimports]

I am in desperate need of helps and suggestions! I have a 1971 240Z that I cant get to run correctly. I will try to be as detailed as possible in explaining my dilemma. I would like to preempt your responses with sincere gratitude as I have about given up in my attempts to solve this problem. I go to college in WV and don't have the money to cover the mechanic bill to fix my poor z car.

Specs: 1971 240z, rebuilt straight six, one wire alternator

Tools at my disposal: Every hand tool imaginable, a timing light, a carb sync tool

First, I bought my z with four working cylinders so I, along with the mechanic that worked there, rebuilt the straight six. After we were finished, the engine ran very rough, so I drove it over to my favorite mechanic who tuned carbs with only a screwdriver in about two minuets flat. I drove the z pretty often for a couple years after that *before heading off to college. After totaling my other car, I decided to drive my z to college. I drove it an hour and a half there and back several times until it broke down on me. I then towed it back home.

It took me a couple months to figure out the problem. In these couple months, me and my father had turned and returned every screw on the carbs so much that by the time I figured out that the problem was that the stupid bolt underneath the distributor had turned a half an inch, it was way too late. Now, I could only get my z to run for a very few rough seconds before it died. I then abandoned the z again after failed attempts to retune the carbs and headed back to college.

Now, onto my senior year, I decided to tow the z back to college and try to fix it in-between studies. I missed it I bought a Datsun repair manual and did my research. Through fine Datsun form sights such as this one, I was starting to make progress. I first bought a carb sync tool. I synced my carbs and played with balance screws and adjusted nuts through the directions of my manual. I also experimented with the distributor. First, I took it apart in order to better understand the part and ended up cracking the coil inside it. After a brand new distributor from auto zone I was back in business. I looked up how to get the timing from the manual and the internet. I found top dead center and set up the timing as best as i could.*

I*made great progress and actually got it sounding half decent for the first time in years. After attempts of fine tuning I actually ended up making it very much worse.*Then, realizing adjusting the carbs wouldn't make any difference unless the car was timed correctly, I bought a timing light. This is where I am currently stuck. As I look at the timing light, I am about four or five inches away from the mark! How is this possible?! As I turn the distributor closer to the mark, the car dies. Clearly something I did was wrong. If I can't get the car close any timing marks, how can I even begin to tune this motor? I am at a complete loss and need help!*

I don't know very much about motors, as I am just a body man. I learned some when I helped to rebuild the motor and from the internet and manuals but that's it. I have always been a do it yourselfer and refuse to bring it into a shop. Thank you all very much for your help. It is very much appreciated!

[SteveJ]

Are you SURE you didn't install the distributor 180 degrees out?

[FastWoman]

First step: Make certain your distributor's breaker plate isn't frozen up. Most are. Remove the distributor cap and rotor, and try rotating the breaker plate back and forth by hand. It should move freely, and it should be under spring tension. You should also be able to move the breaker plate by sucking really hard on a hose connected to the distributor's vacuum advance. If the breaker plate is stuck, as most are, you'll need to fix it. You can get a rebuilt one from your local auto parts store for maybe $125.

Second step: Put your engine at top dead center via the notch on the crank pulley, and make sure that really is TDC. (Sometimes the crank pulley can be off, I suppose because the woodruff key becomes dislodged.) To confirm that the engine is at TDC on the correct mark, see here: http://atlanticz.ca/zclub/techtips/tdc/index.html

Third step: Make sure the cam is in the correct alignment. The cam turns once for every two rotations of the crank. You're at TDC when the crank's timing mark is at the 0 deg mark and when the two forward-most cam lobes are pointing up, rather than down. (Look through the oil filler hole.) If the lobes are pointing down, give the engine one complete turn.

Fourth step: Make sure the distributor is aligned correctly. The rotor should be pointed to the #1 post, and the plug wires should be aligned as follows:

All this should get you somewhere in the correct ballpark.

Edited December 25, 2010 by FastWoman

[ChrisZ]

What Sarah said, just notice that there is 3 different type of pointers and harmonic balancers, if they have been mixed up, so when you have piston #1 at TDC and the notches on the cam is pointing up, then check and see if the pointer is a 0, if not, make your own mark.

Make sure your plugs and plug wires are good.

When all this is done and you can confirm your ignition is correct it is time for you to look at those SU's

Make sure they are clean and there is no gunk in them, also make sure the hose from float chamber to nozzle is not collapsed, it have to be flexible, if you want to re-new it, you should get it from Ztherapy.

Now start by turning the mixture screws all the way up to closed position and then turn them 3.5 turn down (clock wise from above), this should get you started and you should get a idle, then balance, now all you need is to get a correct mixture, balance the high idle and you will be just about there.

When the engine is hot, it is time for you to adjust the valves.

Chris

[kenz240z]

Another thing you might check is to make sure the bolt that secures the harmonic balancer to the front of the crank isn't loose. I had that happen to me once and it drove me nuts, because the car would run for a bit, then die on me. The gear that drives the distributor fits on the nose of the crank behind the harmonic balancer. Thus, it was able to slip forward and throw the timing out of adjustment...