Need help with tune up and fault identification

[wenzlern]

Hi,

I just bought a 240z which has some engine issues. In short: The idle is very rough and initial pickup out of neutral slow. The biggest problem: The engine won't rev over 4000 under load (2nd gear and up). I did reset the point gap which made the idle a bit better (Before it would misfire and run on only 5 cylinders in idle. Then again, the gap was about half what it should be...).

Since the valve train sounds a bit too noisy to me, and the valve clearance could be the source of the 4k problem, I measured the valves. If the measurement has been done correct ( I think it is, however it is the first time I did it) the Valve clearance is way to big. However I was not able to loosen the locking nut for the valve adjustment. And at the moment I am kinda stuck. I don't know whether there is some kind of a trick, I am doing it wrong or the nuts are just very tight...

Would anybody with some experience in the Region LA/Anaheim be willing to help me out?

Or can anybody recommend someone/a Garage that would be willing to help me and knows this engine?

I am going to try it again tomorrow evening, this time with a cold engine.

Thanks,

Nils

[beermanpete]

The lock nuts for the valve adjustment can get very tight. I had to buy a longer wrench to get enough leverage to loosen mine the first time I adjusted the valves. If your wrench is not so long that it hits the strut tower when working on the #2 cylinder consider getting a longer wrench.

[SteveJ]

Another alternative is to tap the end of the wrench with a brass hammer.

[Captain_Zeros]

science!

[djwarner]

Before touching the valves, measure them. Even clattering valve will not greatly affect performance as you describe. I would verify you don't have any vacuum leaks first. Our cars with their 40 year old rubber is great for hiding cracks in the small vacuum hoses. Another problem can be frozen distributor centrifugal advance weights.

[psdenno]

How old and in what condition are the spark plug wires?

Dennis

[wenzlern]

Before touching the valves, measure them. Even clattering valve will not greatly affect performance as you describe. I would verify you don't have any vacuum leaks first. Our cars with their 40 year old rubber is great for hiding cracks in the small vacuum hoses. Another problem can be frozen distributor centrifugal advance weights.

Hi,

Thanks for all the help. I actually managed to get the valves adjusted yesterday (Cold and with some tapping on the wrench it worked out). The valves were pretty out of specs. Some by factor 2!

It already runs a lot better than before and revs up to 5000 under load. There it starts to misfire. But I haven't had a change to set the timing right yet. I will set that today, and if I can get around to it also the carbs (The back 3 plugs are pretty black...). I will try balancing with a tube, since I could not get hold of a Unyson flow meter (Does anybody know, which auto parts/tools store sells them?).

I'll let you know if I am succesfull. If the tune up does not deliver the results, I will start chasing vakum leaks.

Best,

Nils

Edit: Distributor was the first thing i checked. It is fully rebuilt and works like a charm. I just had to set the point gap right. Spark plugs and wires are all new.

Edited April 9, 2013 by wenzlern

[SteveJ]

Edelbrock 4027 UNI-SYN CARB. BALANCING : Amazon.com : Automotive

unisyn | eBay

https://www.google.com/search?hl=en&tbm=shop&q=unisyn&oq=unisyn&gs_l=products-cc.3...1930.3858.0.4089.10.7.2.1.1.0.105.550.5j2.7.0...0.0...1ac.1.Vesar73IZTo#hl=en&tbm=shop&sclient=psy-ab&q=unisyn+carburetor&oq=unisyn+carburetor&gs_l=serp.3...3531.7257.0.7503.11.11.0.0.0.0.350.1329.8j1j1j1.11.0...0.0...1c.1.8.psy-ab.A45yZF7kDro&pbx=1&bav=on.2,or.r_qf.&bvm=bv.44990110,d.eWU&fp=4ae7c0460bab4d43&biw=1680&bih=884

Take your pick

[LeonV]

Save yourself the trouble and get a STE-SK syncrometer instead of a Unisyn. Same price and magnitudes better. I gave my last Unisyn away for free...

[SteveJ]

Thanks, Leon. I couldn't remember the name of the other one. I have that hiding in my garage somewhere, though I'm sure it's not sitting next to the Unisyn.

[LeonV]

Thanks, Leon. I couldn't remember the name of the other one. I have that hiding in my garage somewhere, though I'm sure it's not sitting next to the Unisyn.

Sure thing.

[Gary in NJ]

http://www.amazon.com/Empi-Universal-Carburetor-Synchronizer/dp/B0075AW6CI/ref=pd_sim_sbs_auto_1 Edited April 10, 2013 by Gary in NJ