Timing Off Runs Bad

[ZNate]

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!
 

[SteveJ]

With the car at TDC on the compression stroke, take a clear photo (preferably close in) on the pulley and timing index.

Then take off the distributor and take a photo of oil pump shaft where it turns the distributor.

[Zed Head]

55 minutes ago, ZNate said:

During the ignition change I found the timing before at 1-2 degrees ATDC with points

 

57 minutes ago, ZNate said:

20 degrees BTDC after Pertronix install.

55 minutes ago, ZNate said:

adjusted the timing by drivability and the ping test.  It ran decent enough.

 

56 minutes ago, ZNate said:

when using my timing light I cannot find the timing marks and I have no more adjustment left on my distributor

 

56 minutes ago, ZNate said:

find the compression stroke.  The plug popped out like a champagne cork, but I do not see my timing marks.  

 Kind of seems like the damper might have slipped and might still be slipping.  You used to be able to see it, but it wasn't really in the right place.  2 degrees retarded is pretty far off, if the points were correct for the engine in the beginning.  Then it was at 20, you could see it, but now it seems to have moved again.

See if you can move the pulley on the crankshaft end by hand.  Wiggle twist torque on it.  See what happens.

[siteunseen]

If it ran so so with full choke on new carbs then I think I would check float chamber levels and fuel delivery. Close off the return and see how it runs. That should build more fuel.

[Zed Head]

It might be worth pulling the valve cover also and lining up the notch and groove on the cam sprocket.  It should be within a few degrees of TDC.  You should certainly be able to see the marks then.

Also possible, I think, that the rebuilder pushed the crank woodruff key through the slot during the rebuild and the damper is spinning/moving on the crank.  Just a guess, based on what you wrote.

2 hours ago, ZNate said:

with 139K (engine rebuild at 134K)

 

Edited July 12, 2022 by Zed Head
- nark + mark

[ZNate]

Appreciate the replies.

Spent the last hour trying to find TDC for the #1 piston to take photos and help with the diagnosis.  Having no luck getting the "cork to pop" at TDC.  Will post my results once I get a quick break.

[ZNate]

Sorry for the delay, technology problems.

Finally got the cork to pop at #1 TDC, so I took the requested photos.  The timing mark is difficult to see, but the silver pointer tip is    pointing to the dark spot, which is zero.  The 5, 10, etc. marks are above the 0 marker.

Surprisingly, all the marks line up, but I think I’m not quite at 11:25 with the oil pump shaft.

Since my #1 plug wire is currently placed at about 12:30 and the rotor spins counter clockwise, the spark plug is igniting in advance of full compression.  So I think that's the problem.

Maybe I can move the #1 wire one to the left, which is currently #5 at about 11:00 to get my timing correct.

 

[SteveJ]

11 minutes ago, ZNate said:

Sorry for the delay, technology problems.

Finally got the cork to pop at #1 TDC, so I took the requested photos.  The timing mark is difficult to see, but the silver pointer tip is    pointing to the dark spot, which is zero.  The 5, 10, etc. marks are above the 0 marker.

Surprisingly, all the marks line up, but I think I’m not quite at 11:25 with the oil pump shaft.

Since my #1 plug wire is currently placed at about 12:30 and the rotor spins counter clockwise, the spark plug is igniting in advance of full compression.  So I think that's the problem.

Maybe I can move the #1 wire one to the left, which is currently #5 at about 11:00 to get my timing correct.

 

 

The oil pump looks like it's about a tooth off. Maybe someone with more experience will chime in. 

This is how it should look: (Courtesy of a post by @siteunseenfrom 3 years ago)

Also, the pickup location on the distributor does not look right. Every Pertronix install I have seen has the pickup closer to the radiator like in the photo below.

Also, see the photos in this thread: 

You might also want to put some bright (or fluorescent) nail polish on the timing mark while you have it at TDC. That will make it easier to see with the timing light in the future.

 

 

[Reptoid Overlords]

Probably just my eyes, but do the timing notch and cam pulley notch seem to be lined up too even?  I've always seen it to be that the notch is advanced just a tiny bit.  Perhaps it lines up different at the number 2 position somehow?

 

Edited July 13, 2022 by Reptoid Overlords

[ZNate]

Thank you for the suggestions.  Attached are four additional (better) photos.

SteveJ: It appears the Pertronix unit only fits into the Mallory dual point distributor one way.  The rotor position and the oil shaft appear to align.  Used a Testors Enamel paint pen to highlight the timing marks better.

Reptoid Overlords: Cleaned up the cam pull notch and the alignment appears to be good.  My engine internals need some cleaning.
 

[Zed Head]

38 minutes ago, ZNate said:

the Pertronix unit only fits into the Mallory dual point distributor one way.  

Put the #1 spark plug wire on the terminal that the rotor is closest to when all of your marks are linked up and the distributor is in a place which gives you adjustment range.  You might get you timing light marks back then.  Then you can set your timing and focus on the carbs.

[ZNate]

Zed Head: Based on your suggestion, this is what the #1 plug wire move will look like.

Will make the change and let you know the results.