I have a 1982 Datsun 720 4x4 with Z22 engine. I've had it for about 2 years and growing more and more frustrated with the LZ style of engine. Very hard to work on and low gas mileage. Today I acquired a 1978 620 with good engine but trashed body and electrical.

I want to retrofit the 720 by installing the 620 engine. Anyone heard of this being done before?

I know the bolt holes will all line up since the L and LZ series shortblocks are essentially the same. My concern is that the flywheels and/or clutch pressure plates might be different thicknesses.

Any tech data to confirm/deny this?

You'd have to use the 78 engine and transmission because the trans that goes with the LZ engine is set up to match the tilt of that engine and things just won't line up right if you mix the L engine with the LZ trans and vice versa. I'd use the 78 clutch etc. if I were doing the swap.

Wow, I never would have guessed the engines are tilted differently. Thanks for the tip.

Swapping the engine and tranny as a unit also solves the clutch question because I'll just leave that in there. I'll have to go measure the length of the trannies and make sure the shifter comes up in the same spot.

So far so good, everything measures up. The upper radiator connection is on the opposite spot but I can make a custom hose.

The only thing I see as a possible problem is hooking up the distributor. The LZ has dual coil running to 8 plugs where the L has single coil to 4 plugs. Are the inductor/reluctor specs pretty much the same? The L has red and blue wires going to the terminal block while the LZ has red, blue and black/white. Looking at the schematic (I only have it for the LZ) the red goes to one coil, blue to the other and b/w is the common. Red also seems to be the only wire that feeds to the tachometer.

My plan is to connect red to red and blue to black/white and see if that works. If not then I'm in trouble.

These should be of some help. Go to http://www.olddatsuns.com/620tech.htm#wd and scroll down to the Datsun 620 section. There's a 78 wiring diagram and also the entire 78 620 FSM.

you could also switch for the s13 radiator for a little better cooling and lining things up. i have one in my 720

You may have smog legality issues. not sure what types of inspection issues you have in Boulder.

Aside from the fact you already have the parts, finding an EFI Z24 from an Early HB sounds to me like a lot better swap for drivability.

It's smog exempt because of being over 25 years and I had it listed as a collector. Even so I think it would still pass. The Z22 carb is set to run a little rich so there is fuel to blend with the air bleed into the exhaust manifold. That ensures the cat will always have something to eat and stay at operating temp. Trouble is the air bleed pipe cracked and the fitting on the manifold was plugged so getting the earlier engine would probably run a bit cleaner.

I'll be curious to see how the power steering can be dealt with. Since the 620 has no PS, I won't bother to switch the pump right away. I'll see how driveable it is and maybe it will build up my arms. I'd rather see about switching the steering boxes out to not have the MPG drag on the pulley. Not sure if a 4x4 will take a 2wd steering box.

I know this thread is hella old.

But i have been thinking about this too. There are a few things to consider. 1980 was kind of a unique year. Lets get a few things going here.

The problem first being that 1980 had the differential on the passenger side. after that it was moved to the driver side. 1980 was the only year they made the oil pan for the l20. they are kind of a pain to find. I lucked out and have 2.

With that being said. You will need to use L20 motor mounts. Now, you CAN use the naps z transmission. Just swap the bellhousing off an L series transmission. Tada. If you dont want to modify the oil pickup tube and oil pan. you might get away with just making your own motor mounts to make it sit a little bit higher than stock. should help with clearance issues. i dont know however if it will still clear the hood or how much room you will have afterwards. you could always install a hood scoop?

Another thing to think of. the early 720 pickups had 4.11 gears, the later had small gears. 4.7?? or 4.3??. Sorry, i don't remember wich is what year after 1980. However, you will want the 4.11 gears running an l20. It is under powered quite a bit compared to the Naps Z

Thats my take and what i have seen and learned anyways.

The diff for the Z22 has a ratio of 4.625 so you'll need to consider that. Using the L tranny might help with the losses due the the ratio on the diff.