My Z runs horrible and I’m unable to locate my timing marks when the #1 piston is at TDC.

Have a 1970 240Z 5speed, with 139K (engine rebuild at 134K). Performance modifications: Fujitsubo Legalis R Exhaust and Trust GReddy JDM Exhaust Headers.  

PO installed a Mallory dual point distributor, which I changed to Pertronix version 1.  During the ignition change I found the timing before at 1-2 degrees ATDC with points and 20 degrees BTDC after Pertronix install.  I’m sure that change had something to do with the electronic pickup.

I was unable to retard the timing much due to adjustment limitations on the distributor, so I adjusted the timing by drivability and the ping test.  It ran decent enough.

Fast forward to last week, original carbs were impossible to adjust, so I installed replacements from ZTherapy.  

Prior to carb installation I checked and re-gapped the plugs, adjusted the valves and checked the timing.  With the new carbs, the car ran great with full choke, but horrible once warm.  The lowest idle with the car still running was 1300 rpm.  

I knew the timing was off, so I checked the oil pump shaft and found it at 1:35 (rotor at 12:00/#1 plug wire), instead of 11:25.  I set the engine at TDC; timing marks/pointer, cam lobs and piston at “what I thought was” compression stroke, based on the manuals.

Reinstalled oil pump shaft to 11:25 and bolted down distributor so I would have room for adjustment.  The Mallory rotor now installs after the 12:00 position, so past the #1 plug wire.

(I’m at 620 feet above sea level, so I found out last night I was running the carbs too lean at 2..5 turns out.  So my mixture should be 3-5 turns out based on elevation.)

Car still runs horrible, even with the mixture screws out to 3.5 turns.  In addition, when using my timing light I cannot find the timing marks and I have no more adjustment left on my distributor.

Today, I pulled the #1 plug and inserted an old rubber plug to find the compression stroke.  The plug popped out like a champagne cork, but I do not see my timing marks.  

I’m stumped.  Will appreciate advice on getting my car running right with these new carbs.

Thank you!
 

Zed Head: Thank you for the advice.  

My valve cover gasket no longer usable, so no start attempts until Friday at the earliest.  No gaskets available nearby.

Buy a Nissan valve cover gasket. They hold up a lot better than the aftermarket ones.

Here is the current part number: 13270-Y7010. You can order at your local dealer or an online dealer like https://www.nissanparts.cc/

Edited July 14, 20222 yr by SteveJ

SteveJ: Thank you for the Nissan valve cover gasket details.  Once I saw your note last night I ordered a Nissan gasket from a well known Z Car parts house and it shipped this morning.  Delivery is scheduled for Saturday.

Pro tip: Don't use RTV on the valve cover gasket!

I was working on a guy's 280ZXT last year and found some idiot used RTV on the valve cover. I convinced the owner to replace the gasket since I was going to do a valve adjustment. I was delayed on the valve adjustment because I was picking off pieces of RTV from the camshaft and other places under the valve cover.

Still no luck; unable to start the car.

Since last Wednesday, July 13, I moved the plug wires on the distributor one to the left (counterclockwise).   The rotor at TDC (11:25) is now before the #1 plug wire at 10:00 on the distributor.  The new Nissan valve cover gasket is installed.

While cranking I’m getting slight backfiring through the carbs and unusual odors, but it will not start.  I think the rotor is not close enough to the #1 plug wire on the distributor now.

I’m beyond frustrated.
 

Did you retard timing any after moving the wires? It might be too far advanced.

SteveJ: Thank you for the suggestion.  I'll try to retard the timing more.  Was not sure which way to go advance or retard.

Have the distributor turned counterclockwise to the stops, but backfiring through the carbs continues.

Do I need to reset everything back to TDC and move the oil pump shaft 1-2 notches to the left (counterclockwise)?
 

Edit: Some things got clipped out by mistake.

Does your distributor still have a plate like this?

Here is how it's lined up on my 240Z.

Here's what you might try to do before messing with the oil pump. (Minimize jumping around.)

1. Set the car at TDC.
2. Align the mark on the plate to the middle.
3. Verify that the rotor is at the #1 plug.

From there, you'll have a better idea of what way you need to go.

 

 

Edited July 17, 20222 yr by SteveJ

SteveJ: My adjuster is the same and I lined up the center marks when I installed the distributor.  My adjuster works a little strange though, it will advance a mark or two, but the retard adjusts past the "R".

The rotor points to 11:25 and my #1 plug wire is at 2:00, so they are not close.  I could move the #1 plug wire back to 12:00 on the distributor, but that's where I was missing my timing marks and the engine ran horrible.

49 minutes ago, ZNate said:

SteveJ: My adjuster is the same and I lined up the center marks when I installed the distributor.  My adjuster works a little strange though, it will advance a mark or two, but the retard adjusts past the "R".

The rotor points to 11:25 and my #1 plug wire is at 2:00, so they are not close.  I could move the #1 plug wire back to 12:00 on the distributor, but that's where I was missing my timing marks and the engine ran horrible.

There should be two adjustment bolts for timing. Have you played with both?

If you have, and what you said still holds, here is what you might do.

1. Put the mark at the first line past the middle and toward retard. Consider that your static zero position.
2. Adjust the oil pump from there to put the rotor at TDC.

Still this picture bugs me.

In the 240Z, I could swear that when the engine is at TDC, the rotor is near the Hall effect sensor, not 180 out like in your photo. 

I tried searching for images with your setup, and I tried searching Hybridz. I didn't find anything useful.

Maybe someone smarter than I am can chime in about this.

Don't forget that the spark happens when the magnet on the shaft passes by the Pertronix sensor.  One more thing to line up.  Trigger, rotor, compression stroke on #1, plug wire.

The magnets have been known to fall off.