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PostPosted: Wed Apr 10, 2013 1:28 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
Posts: 331
Location: Finland
I have a couple of issues with my early -74 260z. I had the head ported, with a stage 2 Schneider Cam installed. Prior to this the engine was equipped with a 4barrel Holley and ran beautifully. The head was installed, with cam timed initially to a setting that the mechanic who ported the head told me to use as a starting point (with adjustable cam sprocket). Dizzy is Mallory Unilite and it is set exactly the same as before the mods. Vacuum from the dizzy is now unconnected as I have installed triple Webers. Not yet plugged. The Webers have been completely cleaned, new gaskets, jets, venturis, pumps all with values that were determined to be a good starting point for this setup. The carbs were set to a starting point as described in the Weber book. No further adjustments have been done so far.

The engine starts fine and idles well, although a little high at the moment. I have let the engine idle a good 5-12 minutes and then try to drive just to move the car but it stalls instantly under load unless I give it a good throttle, but it really takes quite high revs to prevent it from stalling.

Any ideas why it stalls? Can I help it by adjusting the initial timing? Please understand, the timing and carbs WILL be set up by a pro later on. Now I need to be able to move the car in and out of my garage, so I need to get it work well enough to be able to drive her just a little bit.

Also I keep having this strange starting problem: (I have cleaned all cables, earth connections many times, so the problem must be somewhere else): Usually when cold, she starts up nicely. No problems. Sometimes though, only click, click, click. I will start her, let her idle for 10 minutes, try to drive, she stalls. Try to restart. Sometimes starts well, other times click, click, click. Yet sometimes she will crank really well but gives no signs of even trying to fire up. Like there is no spark. Now, I have tried another ignition transistor unit, a new ignition switch but the problem keeps coming back. Then a few days later she starts instantly. So the problem comes and goes away just like that. Could be a lose, cracked soldering maybe somewhere. But where??

Could this be a relay problem? Can I replace the starter relay (I think there is one..) with a modern, generic type relay and does anyone know what type to use?

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PostPosted: Wed Apr 10, 2013 1:54 pm 
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Location: Niagara falls, NY
What kind of fuel pump are you using? And plug that vacuum leak!

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PostPosted: Wed Apr 10, 2013 3:09 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
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Location: Finland
I have a new electric Carter pump with Holley pressure regulator. I'll plug that leak ;)

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PostPosted: Wed Apr 10, 2013 3:45 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
You switched to Webers. They don't require vacuum advance for your timing, but they must have all the timing done by the mechanical weights in your distributor now. In other words, the mechanical weights must now do ALL the work for your ignition advance/retard. Therefore, you must have your distributor "re-curved" to provide this ability.

Recurving requires the exchange of weights for different weights, and springs for different springs. It must be done on the bench tester, so they can watch your ignition curve while spinning your distributor. Takes about an hour. Your car can stay home ~ your dizzy must visit the shop.

BY ALL MEANS, plug that vacuum hole! No car can run well with a vacuum leak.

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PostPosted: Wed Apr 10, 2013 4:03 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
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Location: Finland
yeah, I meant to plug that vacuum hole but it was one of those "quick things" to do that I could do "later", once I'm more close to getting the whole setup tuned. (Right now my fenders, cowl panel are off etc so I didn't meant to drive it yet and therefore this little thing was left undone..)

Anyway, I must take the dizzy to a specialist. I originally thought I have to leave it for the shop that will tweak the carbs and set the timing right because I thought they must do it simultaneously with those.

So for them to do he dizzy, what do they need to know about the engine? It surprises me they can do just with the dizzy.

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PostPosted: Wed Apr 10, 2013 10:34 pm 
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Location: CT
They put the dizzy into a bench tester and spin it at various speeds. You tell them the size and make of your engine, and the size and year of your Webers. They have the charts to recurve your distributor for that information. Changing jets in your carbs will not make much difference for your distributor (in other words, you can change jets to match weather conditions or certain race tracks or altitudes, and the newly curved distributor will handle it well).
BTW, please make sure you are not running Champion, AutoLite or AC spark plugs. Z cars hate those and strangely, they can cause many of the problems you are describing. Stick with NGK, Bosch, or Nippon Densu always.

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PostPosted: Fri Apr 12, 2013 1:59 am 
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Location: Finland
Thanks again Frank! I already have NGK plugs and they have been great.

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PostPosted: Fri Apr 12, 2013 9:45 am 
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Location: Finland
I plugged the vacuum hole in the dizzy and then I managed to drive her into my garage without stalling.. :) It was a bit nerve braking, since she's automatic, and as nothing's been tuned yet, and even the carb cable setup is rudimentary, all this results in a very difficult to control throttle action. And as I have no clutch, and needed more revs than normally to avoid stalling, I had a fear that the car would rocket into the back wall of my garage, but I managed to get her in nicely :)

As for the starting problems I'm still lost.. This morning she started instantly. Other times clikcs, the again sometimes cranks but won't start..

From now on, I hope to make quick progress on EVERYTHING :)

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PostPosted: Fri Apr 12, 2013 10:58 am 
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Location: CT
This clicking thing is a mechanical/electrical problem in the starting circuit. There could be several problems:

1. weak battery
2. starter or starter solenoid failing
3. start switch (under key) failing

If you decide it's the starter switch, be sure to replace it with the exact model for your year car. They changed frequently due to additional options and not every year switch works with every year car. Study the prong pattern when ordering a replacement.

This is just a guess, but because the engine sometimes turns over but doesn't fire, I would tend to suspect your ignition switch (under the key). I can picture it being *just* corroded enough to cause momentary failure to operate the starter "sometimes", and corroded enough to cause an interruption to the primary ignition circuit during START "sometimes", and still good enough to allow full proper operation "sometimes".
If you want to discuss the construction of the ignition switch/Steering wheel lock combination, we can.

Congratulations on not wrecking your baby while the controls were tenuous! :wink: Well done, sir!

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PostPosted: Fri Apr 12, 2013 11:15 am 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
If you decide the problem is your ignition switch, you can order them thru Rock Auto rather quickly.

http://www.rockauto.com/catalog/raframe ... 97-1699546

They offer several brand names:
AirTex (for $9.00)
Beck/Arnley (for $18.00)
Standard Motor Products (for $20.00)

Be sure to tell them you're a CTZCC member when ordering, for a 10% discount. We have a code word, somewhere ~ anybody remember what it is?

Just be sure to count the blade connections on your plug when ordering, and get the correct blade-count on your replacement part.

ALSO, while you're upside down under your steering wheel anyway, look at the female recepticles in the plug which pulls off the back of your starter switch. After 40+ years of electrical conductivity and changing weather, you can build up some green crud in there which stops electrons from flowing where they need to be. I've seen guys sandblast those connectors with outstanding results ~ the thing works like new with a little cleaning.

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PostPosted: Fri Apr 12, 2013 12:29 pm 
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Joined: Sun Apr 01, 2012 4:19 pm
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Here it is:

http://forums.ctzcc.com/viewtopic.php?p=46838#46838


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PostPosted: Fri Apr 12, 2013 2:41 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
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Location: Finland
Yeah Frank, those are the most common issues and in my case I have had these problems with 2 batteries that I have made sure are fully charged and that work fine on other cars, I have changed the ignition switch (it's from Rockauto :) but also with that I have had the same problem AND I have a brand new starter too.
All I can do now is just see if it keeps coming back and try to isolate the problem.

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PostPosted: Fri Apr 12, 2013 3:55 pm 
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Location: CT
*(thank you for finding that, Filipe).

WELL. Congratulations, King. You have a certified "Gremlin".

Something in your electrical starting circuit is shorting or opening OCCASIONALLY. That's usually the hardest problem to solve in the automotive world, because it's so hard to locate. Once you find it, it's usually easy to fix).
It might be OK when you first check the circuit, causing you to assume eveything's good up to that point, and move ahead to other possibilities. But then it shorts or opens on the next try and, because it was OK before, you don't even consider it a second time. :?

Somewhere in your manuals you will have a wiring diagram of your starter circuit. They are very straightforward and simple, compared to all other circuits. Yours would typically only involve the battery (and Fuseable link), the starter switch, the starter/relay/solenoid, the primary ignition circuit (involving the coil, resistor and Dizzy), and because it's a Datsun Z, the 4-way flasher switch. I don't even think the Alternator was included in most Z starter circuits after early 1970 (could be wrong).

Somewhere along that route you have a weak connection which is causing a temporary short or open. If it's a short it would be a small wire (rather than the battery itself), or else you would get arcs and sparks from the battery cable area, which is not happening to you.

Trace the starting circuit on the diagram, then follow it by hand on the car, trying to wiggle each wire and connection. This is a PITA but I don't know of any other way to do it. If/when you find any connection which appears suspicious, loose, or funny color, that's probably your problem. If all connections appear OK, then you should suspect wires rubbing against ground, or bent and fatigued to the point of breaking inside the insulation sheath, but occasionally still touching to allow the car to run awhile. If you don't find either of those problems, you should suspect an internally-faulty component (a bad coil, resistor, switch, etc).

I know this is going to sound weird, but there is a small possibility that the problem could be with your key/steering wheel lock itself. I've seen them wear over time to the point that they no longer turn fully clockwise, and stop turning the ignition switch *just* short of full contact. Because the final station on the key's clockwise rotation is a double contact (one for the starter and one for the ignition circuit), sometimes a weird thing will keep it from activating both circuits. This can be tested by disconnecting the switch from beneath the key and turning the switch itself with a screwdriver blade. If the problem goes away immediately, you've been lucky and found the problem. The bad thing is that a new key set for the ignition is not very cheap.

That's about all I can think of for now. Others probably have their own experiences they can tell you to check.

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PostPosted: Fri Apr 12, 2013 4:07 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
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Location: Finland
That's good stuff again Frank ;)
I'll do what you suggest and try and find the culprit.

BTW I forgot to mention that the car is equipped with a start button. It was installed by the previous owner, and it works by turning the key to "on" and then operating the start button. It was probably installed because the key is worn. Sometimes I start the car using the key, not the button (just because it is a reflex to turn the key all the way and when it happened a few times, I noticed that the car can sometimes be started with the key, sometimes it can't)

Anyway, because the button switch itself is good, I think the problem is not in the key lock - well, yes it is, but it has been bypassed. I do suspect a relay or something else than a wire, as I have checked all wires and cables many times. The thing is, the "cranks, won't fire up" scenario usually happens when the engine is warm, the click usually happens when she's cold. The click may still be due to battery that has not been fully charged: the same battery with the same charge was able to start my 200SX 1,8litre 4 cylinder engine when cold, but did not start my L26. I then assumed the battery is good, but obviously the L26 takes way more power to crank than the CA18DET. So I'm not really concerned about the click as of yet, it's the other scenario that I must solve.

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PostPosted: Fri Apr 12, 2013 4:09 pm 
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Joined: Fri Apr 02, 2010 2:56 pm
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Location: Finland
Filipe wrote:


Yes, thanks for this, Filipe, it's useful to have this written down and not having to search the forum every time ;)

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