New Owner of a 720. Retiming the dist.

[MarkR]

Hi, I have a 1980/81 Nissan 720 4x4.  I have cleaned out the old oil, radiator, replaced the plugs, oil and air filters, cleaned the carb and reset the valves and points.

Engine starts but I had to set the manual choke a little closed to keep it idling, engine revs but has a flat spot sometimes coughs through carb or backfires. when I switch off it runs on for a few minutes then dies (dieseling?) anti dieseling solenoid not connected it has no wires.

Then i checked timing and discovered that the timing mark is after TDC by about 15 degress and I cant adjust the distributor.

Is the timing chain perhaps misaligned or the distributor.

I really would not like to take the front cover off unless I really have to.

Any advise would be appreciated

[AtomChurch]

You might be able to just pull the distributor and oil pump to reset them.

I don't mess around with 720's on a regular basis. Someone else probably knows exactly what to do though.

 

Did you search around the site for a bit before posting?

Answers are all around. Just have to find out where to look.

[Draker]

Do what atom said

[Draker]

Sounds like the oil pump drive spindle is off a tooth.

[datzenmike]

Timing chain is totally separate from the distributor drive.

 

Flat spot and back firing may be the retarded distributor timing.

 

 

 

Set the engine to TDC on the #1 compression stroke and unbolt the distributor from the timing cover and lift it away. You should see this...

 

 

This is the correct drive spindle position that will place your distributor in the correct range to adjust your timing. The distributor can only fit in one position and that position is set by the drive spindle below it.

 

Note that there  is a large and small side to the half moon shape on the spindle top.

 

If the spindle is not in this position it will need to be placed in this position. To do this the four oil pump bolts need to be removed and the oil pump lowered. Be ready with rags as it will drip oil. The spindle drives both the oil pump below and the distributor above it so it can be turned and put back in.

 

Align the oil pump body and the spindle like the picture below and install. Check that the distributor end looks like the top picture and tighten the oil pump mounting bolts. The gasket is paper thin and if not torn can be reused.

 

Your distributor should now have the rotor pointing to 9 o'clock (or toward the rad) as viewed from the driver's fender side, and at 4 o'clock, and within the proper timing adjustment range.

 

[banzai510(hainz)]

olddatsuns.com has my vedio on you tube on L motors

 

fix the dile selinoid  also.

 

 

best to say what motor is in there as there are the 2 plug per cylinder(NAPZ ) and mayb one coil is fireing out out of time.

[datzenmike]

One side of plugs may not fire but they can't fire at different times. The coils fire together. That said, there are 8 wires and they MUST go to the correct plug side. Easy to have them mixed up.

 

 

Pull coil wires off and put old plugs in them. Lay on grounded surface and crank engine over with starter. Got spark on both???

[720inOlyWa]

Far be it from me to correct anyone around here- let alone DatsunMike! But I think the ‘small side’ goes on towards the back, not the front, as he labeled it. (Perhaps I am misunderstanding his  instructions here...) This is a photo I took on disassembly. On both of my trucks, at TDC, the distributor drive blade is at ‘11:30‘, but only really appears that way when you compare it to the seam line in the timing cover. Clearly, the ‘small side’ is towards the back of the engine. I have a better photo smewhere, but I cant find it just now:

 

 

I didn’t know what I was doing when I reset mine and found myself missing the correct tooth on the distributor drive only after bolting up the oil pump yet again! After a few tries, the brain kicked in and I made a tool that totally simplified this job for me. It is a round, 1 inch super magnet well attached on the end of a stick. ere it is, going in to hold the drive shaft in place.

 

 

I add a spring clamp to hold it in place where it belongs while I go back underneath to install the oil pump.

 

[datzenmike]

 Your distributor is simply 180 degrees out. The rotor, at TDC, will be pointing to the rear at about 3 o'clock (intake plugs) and about 10 o'clock (exhaust side plugs) . It will also line up at 90 and 360 degrees maybe also at the split angles between all these too? 45, 135, 225 and 315 degrees. All you need is the intake side plug rotor under or near any intake plug wire or close enough to adjust to it. Then just move all the wires around on the cap in the 1, 3, 4, 2 firing order..

 

The stock distributor cap has the wires marked on them. There is an outer 4 (intake) and an inner (exhaust) circle of wires. Number one intake is at the front of the cap towards the rad and the only way to have the rotor under that plug wire is to have the spindle as shown in my picture.

 

There's nothing wrong with it 180 out, it will still work perfectly. It's just different from all the other Z series dual plug engines ever made. 

[720inOlyWa]

Holy cow!