L20B swap questions (into a 521)

[NSRz32]

Picked up an L20B for my 71 521 which is an L16 truck. Have the 5spd trans and all accessories as it was a full drop out from a 78 truck. Anyway, search makes it seem to be a pretty straight forward swap, any advice on little things I'll need or things that aren't compatible?

 

Thanks in advance

[uberkevin]

The l20b is a bit taller, it could hit your hood.

Not to bad..

 

If you have a bench seat your shifter would be in the middle of it.

 

Some thing else but it's not coming to mimd.

[flatcat19]

Exhaust will need to be lengthened, cuz taller motor. 

 

 

Your shifter will touch the bench seat in 2, 4, and R. You could massage the shifter straighter to avoid contact. Not a deal breaker though. 

Remove the shift plate and turn 180*. Should be enough to make up for trans length. 

 

Front half of 620 drive line that came with a long trans. 

 

 

Um...mod for EI dizzy and IR alt. 

[flatcat19]

Also...good to see you back to posting. I love your 521.

[datzenmike]

I put an L20B into a '72 521 back in the day. Used the L16 oil pan. The L20B was from a car so the 200mm clutch/throwout collar was a match.

 

If you are swapping the 620 5 speed it will be about 5.5" too long.

 

If you want to swap just the engine the stock 4 speed transmission will probably rub the 225mm pressure plate.

[uberkevin]

I've only heard of the front portion of the 620 drive line. Haven't seen a thread of it being done.

 

But yes your stock driveline will not work.

The stock transmission is I think 26 inch and the one you may be putting is should be 31 inches?? Think 31.

 

I feel like I made my exhaust work..

I did end up getting a different down tube but think it was still a l16.

 

You might have a bit of a time getting the motor on the mounts. I found that putting one side on first 'passenger side' then once that mount is on the threads bolt the other to the rubber mount on the driver side and slowly lower the motor to align the holes on the motor..

It CAN be done alone!!

 

If your keeping the long tail tranny you can not put the combo motor/tranny in at the same time, bolted together. 'At least haven't ever seen it done.

 

I'm a small guy. Have done this swap maybe 10 times. Can be done alone.

[Phixius]

some more input.

 

put trans in first then motor. I found out the hard way.  also need to modify the transmission mount.

 

 

Transmission Mount:

The 521 mount can be modified and used. I don't have the exact measurements but once the dogleg is in you should be able to measure it much closer. This is the area to be removed and welded back up.



Modified mount facing the other way.






.

 

 

other ways its been done:  http://community.ratsun.net/topic/43635-transmission-mount-for-5-speed/

 

as for the longtail trans. flatcat is right about turning the lever 180. its what I did.  makes 5th gear a bit of a reach.  youll need to make a new hole in your cover plate. 4 1/4" hole saw works perfect to reuse stock boot. 

 

[NSRz32]

Awesome thanks so much guys. I'll modify the trans mount and shifter plate for sure, that's simple enough. It looks like there should be a pretty straightforward swap.

[NSRz32]

Also, any recommendations on an internally regulated alternator (Rock auto maybe) and electronic distributor?

[datzenmike]

All Nissans switched to internally regulated alternators for '78. There is a problem with room in the 521 and 620 between the right leaning L series engines and the frame on that side. There is the lower rad return hose and the idler arm just below the alternator. Larger output alternators are also larger in size and don't fit well here. I would imagine a '78-'79 620 internally regulated alternator should fit a 521 but it's only 35 amp at best.

 

The EI dizzy was introduced on all '78 vehicles also but the '79 were the matchbox style. Vehicles with L series engines and matchbox dizzys were the '79 620 truck, the S10 (200sx) and the A10 (HL510)

 

For 620 alternator up grades go to the search function here and type in alternator up grades or Saturn alternator on 521 and start researching. You can also type the same into Google and use the word ratsun and it will display ratsun posts about it. Try mixing the words around for different answers. Try this for the Matchbox dizzy also.

[thisismatt]

Haven't really seen anyone else do it, but I put an Eagle Talon/Mitsubishi Eclipse alt in my 521.  It fit fine...just had to get a slightly shorter belt otherwise it ran into the zerk fitting on the idler arm, and switch the serpentine pulley for the V pulley.  I think it's a 65-75amp.  If you look for one, it's the one with the 2 prong plug.  There is another with a 4 prong plug, but I don't know if that fits as well.  They can be found pretty cheap on ebay.

[datzenmike]

I managed a larger 50/60 amp 720 or car alternator by using the Z car lower rad inlet and a 720 alt mount to the block which raises it slightly. Shorter belt too. It worked but you had to put the belt on first then start the two bottom mount bolts. Thinking back I should have just made a bracket that fit the other side under the distributor. You could throw any air pump away and fit any size alternator in there.