L20B in a 521

[76_620]

I have a 72 521 currently has stock l16 with 4spd. I purchased an l20b with 5spd dogleg. My questions are what modifications will I need to get this to fit ? I’m assuming change the oil pan, modify transmission mount, and possibly need to shorten driveshaft ?? Anyone know what exactly needs to be done to make the motor and transmission fit the 521 ? 

[datzenmike]

You'll need to put the L16 oil pan on and the L16 exhaust manifold IF the L20B doesn't have the joined intake and exhaust. Use the L16 engine brackets so it fits the 521's rubber mounts. The 521front  driveshaft spline is bolted into the 4 speed transmission. Unbolt and remove the spline from the 4 speed. The hole covered by the nut on the back of the spline needs a 4omm engine core plug and some sealer to prevent oil leaking out and it will fit and work perfectly on the dogleg.

 

 

Fitted into dogleg...

 

 

Keep your 4 speed clutch arm and the bearing holder and use on the dogleg.

 

_______________________________________________________________________________________________________

 

The mount needs to be removed, sectioned and welded back up so it's shorter...

 

 

 

 

 

 

Set transmission in place measure then cut. wayno or DanielC may know the exact amount.

[76_620]

Verry nice, thank you. I do know the l20b I purchased was pulled from a 510, dose the 510 as well need the l16 oil pan on the l20 to fit ? If so this means the l20 I purchased already has l16 oil pan on it. I don’t l know how to distinguish l16 from l20 oil pan ? 

[DanielC]

Use the stock L-16 oil pan on the L-20-B engine.  It matches the 521 frame.

Use the throwout collar and bearing for the L-20-b engine, it matches the pressure plate.

I like to use the stock 521 throwout lever, with a spring. 

Use the metal engine mount brackets off the L-16 engine on the L-20-B engine, Use the 521 rubber engine mounts.

After the engine mounts are bolted into place, then fabricate the transmission mount.  See this page, near the bottom for transmission mount details.

https://ratsun.net/topic/30606-my-ratsun-datsun-521-now-with-l-20-b-and-a-five-speed/?page=21

The stock 521 speedometer cable can be routed over the top of the transmission, to fit the transmission speedometer pinion.

After the transmission mount is done, then you can get a measurement on the length of the front half of the driveshaft.  The driveshaft will need to be rebalanced as a unit.  The factory service manual specifies a maximum unbalance of 15 gm-cm or 0.2 In-Oz at 4,000 RPM.  4,000 RPM is the approximate RPM of the driveshaft at 60 MPH.

The L-20-B engine is taller than the L-16.  On my 521, the rod that holds the hood open rattled on the air cleaner of the L-20-B engine, I took it off, and just carry the hood stay open rod in the truck.  

Even if you use the L-16 two bottom port exhaust manifold on the L-20-B engine, you may need to modify the exhaust slightly, because the exhaust manifold is about 3/4 of an inch higher on the L-20-B engine.

 

[datzenmike]

8 hours ago, 76_620 said:

Verry nice, thank you. I do know the l20b I purchased was pulled from a 510, dose the 510 as well need the l16 oil pan on the l20 to fit ? If so this means the l20 I purchased already has l16 oil pan on it. I don’t l know how to distinguish l16 from l20 oil pan ? 

 

As Daniel says use the truck oil pan as the 510 pan is made to fit a car the truck's is much different. Don't forget the oil pick up tube as it fit's the pan also.

 

Basically the rear of a car oil pan has room for the steering to cross under it at the back. A truck has to have room at the front for the steering. So the deepest part of the pan is in different positions.

 

I put a car L20B in my 521 back in the mid '70s. It fit and at the time didn't know it was taller.

[76_620]

Verry helpful defiantly feel confident in doing the job. Thank you Danielc and datzenmike. I wish I could post pictures but I’m not too good with the internet and how to post them 

[76_620]

Can the 521 gas tank be removed without removing the bed ??? 

[Crashtd420]

5 hours ago, 76_620 said:

Can the 521 gas tank be removed without removing the bed ??? 

Yes it's just bolted on by a couple brackets... .