240Z WILL NOT run right

[Zed Head]

Sounds lean.  I would do whatever is possible to make it run richer.  I don't know SU's.

[inline6]

I just became intrigued enough to read this thread from the beginning.  My post about accuracy of the distributor connection angle now seems silly to me given that you haven't been successful in getting the car drivable.  My apologies.   

I know it could be many different things, fuel or electrical, but firing back through the intakes and running like complete crap tells me it is timing related.   While you have gone through the steps to verify cam timing, I don't see that you actually confirmed it was all set properly all at one time.  

I think you need to do this again:

• Find top dead center of piston #1 (at the end of the compression stroke - cam lobes for cyl. #1 pointing upward as in your prior pic).
• With the crankshaft in the proper position (#1 piston at top dead center at the end of the compression stroke), verify that the "correct" mark on the crankshaft pully is in "perfect alignment" with the pointer on the engine front cover.  If I remember correctly, the "correct" mark (0 degrees) is the one on the far right when standing at the front of the car and looking down onto the pully marks. 
• With the crankshaft in the proper position, verify the 'dash' mark on the cam gear and "v" on the cam plate are in the "correct" positions.  Reference page EM-25 in the factory workshop manual
• With the crankshaft in the proper position, verify the oil pump/distributor drive gear "tang" alignment is "correct".  Reference page EM-32 in the factory workshop manual:

 

With those things have all been verified, then you know the cam timing is not "off", and the crankshaft damper is not "off" and the distributor drive is not "off".  At that point, you can check ignition timing properly.  

The correct initial timing specification is dependent on which distributor you have.  From the factory workshop manual - if I am not mistaken, US cars were "SU carb. (emission control)":

Which do you have?  Please post the markings/identifications on your distributor here.  17 degrees initial is the correct spec for the euro distributor.  That one is relatively rare.  Confirm the correct initial setting for the distributor you have.

Ignition timing is two different things - initial and "with advance".  For driving around the block, the "with advance" isn't going to be your problem, but it is worth checking while you are at it.  After you have set initial timing for the distributor you have, check the maximum timing also by revving the engine.  Rev to 2k to 3k to 4k and note the timing.  Generally speaking, you should see a progression from your initial value to something between 32 degrees and 38 degrees and it should reach its maximum value before 4k.  If you do not see the timing change from the initial amount to something like this, report back what you see.
 

  

Edited September 14, 2024 by inline6

[BoldUlysses]

41 minutes ago, Zed Head said:

Sounds lean.  I would do whatever is possible to make it run richer.  I don't know SU's.

Well.  This helped.  A lot, actually.  1-2 turns down on each carb, and the car was...actually driveable.  Backed them up again a turn, and the backfiring returned.  Turned them down again, and I was able to cruise around the neighborhood with only slight, occasional missing from the engine (fouled plugs maybe?).

Now, there is a fuel rich black mist coming from the tailpipe, which I don't like, but all the emissions controls have been removed, so maybe that's to be expected?

[inline6]

22 minutes ago, BoldUlysses said:

Well.  This helped.  A lot, actually.  1-2 turns down on each carb, and the car was...actually driveable. 

 

From where they are now, what is the total count to all the way up?  For example, if 2 down made it drivable, then how many turns up until it stops?  3?  3.5?  More?

[inline6]

I am nearly certain that your engine's cam timing or (as well as possibly, and) distributor drive are incorrect.  You need to confirm correct positions on all those things before messing with mixture of the carbs.

[BoldUlysses]

58 minutes ago, inline6 said:

From where they are now, what is the total count to all the way up?  For example, if 2 down made it drivable, then how many turns up until it stops?  3?  3.5?  More?

5 turns down.

12 minutes ago, inline6 said:

I am nearly certain that your engine's cam timing or (as well as possibly, and) distributor drive are incorrect.  You need to confirm correct positions on all those things before messing with mixture of the carbs.

Yes a major effort of the thread has been to ensure everything in the engine is in sync.  I verified that TDC on the #1 cylinder matches the bottom mark on the front pulley, like it should.  The distributor drive tang is correct.  The distributor is timed to 17° because all the emissions controls have been removed from the engine.  Is there something internal about the distributor for emissions-controlled cars (weights, dashpot, etc)?

I'm still unclear as to how to ensure the cam sprocket is on the correct tooth.  Here's the V-and-mark situation:

[BoldUlysses]

3 hours ago, inline6 said:

Which do you have?  Please post the markings/identifications on your distributor here. 

The identification on the distributor reads D412-89.

[Zed Head]

15 hours ago, BoldUlysses said:

The distributor is timed to 17° because all the emissions controls have been removed from the engine.  Is there something internal about the distributor for emissions-controlled cars (weights, dashpot, etc)?

I'm still unclear as to how to ensure the cam sprocket is on the correct tooth.  Here's the V-and-mark situation:

Is the vacuum advance mechanism connected?  It's not an emissions thing.  Not sure what you're saying.  17 is a lot of initial advance if the vaccum advance is connected.

You didn't say if the notch and groove picture is taken at TDC.  Actually you haven't really confirmed the things that were discussed earlier about the damper pulley and the marks.  It would help to confirm TDC and the damper pulley zero mark and the notch and groove and the cam sprocket position.  1, 2, or 3.  You said earlier that you moved it from the #1 position.

[Zed Head]

15 hours ago, BoldUlysses said:

I'm still unclear as to how to ensure the cam sprocket is on the correct tooth.

It's not a tooth, it's the hole that the locating pin uses.

But what really matters is the location of the notch relative to the groove, at TDC.  The locating hole - 1, 2, or 3 - is used to get the notch in the right place.

[BoldUlysses]

35 minutes ago, Zed Head said:

Is the vacuum advance mechanism connected?  It's not an emissions thing.  Not sure what you're saying.  17 is a lot of initial advance if the vaccum advance is connected.

The timing readings are always taken with the vacuum advance line disconnected and the port in the front carb capped off.  750 rpm.

I was asking if there was something internally different (e.g. different weights/dashpot = different advance curve) about the Euro distributor that meant that setting a US-spec one—which I assume I have—to 17° (the non-emissions-controlled spec) would result in poor running once the car was under load and the advance started to kick in.

35 minutes ago, Zed Head said:

You didn't say if the notch and groove picture is taken at TDC.  Actually you haven't really confirmed the things that were discussed earlier about the damper pulley and the marks.

The groove picture above is taken with the engine at TDC, timing pointer aligned with the bottom mark on the front pulley when viewed from the fuel pump side of the engine.  We established earlier in the thread that my front pulley is OK and not separated, so I'm going to trust that its TDC mark is accurate (also confirmed by the position of the #1 piston).

The plan at this point:

• Recheck the cam sprocket
• Clean the spark plugs
• Back the timing down to 5° and see if I can lean out the carbs and still get it to behave.

Edited September 14, 2024 by BoldUlysses

[Zed Head]

I meant in your driving video. 

But, apparently that's the right number.  Assuming that the distributor is the original.

The FSM does not say anything about removing the hose though.  That is definitely a US domestic old car thing.  I'm not sure how Nissan did theirs.  They don't say.

 

[Zed Head]

18 hours ago, BoldUlysses said:

cruise around the neighborhood with only slight, occasional missing from the engine (fouled plugs maybe?).

So, summarizing the state of current affairs, is there a problem besides the 

 

18 hours ago, BoldUlysses said:

fuel rich black mist coming from the tailpipe,