Flywheel
Speaking of flywheel, as previously mentioned in my list of items to have ready, you can use one of three different sized flywheels/clutches.
Noobie lesson #8 – Although I figured this out a few months ago it’s worth noting here - different sized Nissan 6 bolt flywheel/clutches (ie: 200/225/240mm) refer to the friction surface on the flywheel and NOT the actual outer dimension (approx. 30cm).
See my pic below, on the left is a 240mm D21 KA/L flywheel and on the middle and right is a 200mm (middle is a L20B compatible 6-bolt and right is a 5 bolt). Naturally, the 240mm flywheel/clutch will have more clamping force than the 200mm, but it will also require a larger/heavier clutch and PP. Ironically, the 200 6-bolt flywheel was heavier than the 240mm KA example. Personally, I would install a lighter flywheel (KA24 225mm perhaps) if I were keeping this setup. It just makes the car that much more fun to control with the throttle (both accelerating and decelerating).
L16 oil pan and pickup tube
Having two engine stands made swapping parts much easier. While it was relatively easy work, it still took some time to clean parts and carefully swap the pan. My L16 had a leaking oil pan gasket and made a mess of the engine bay. After swapping the oil pickup tube, I took the time to carefully swap the pan to the L20B. I used black RTV bead on the block (scrapped and degreased) and on the oil pan. I let it sit for 15 min then carefully applied the Felpro cork gasket ($10 NAPA) and slowly hand tightened the oil pan bolts in a random order until all were fairly tight (using just the socket and an extender, no ratchet). I let the block sit like that for an hour and then used a ratchet for another ¾-1 turn.
Reinstall
Once the L20B is complete, I reconnected it to the engine hoist and then proceeded to mount the drivetrain stuff. Having a clutch guide pin is VERY handy so that the clutch is properly aligned when the PP is tightened. I also found it to be much easier to lower the block to the ground (supported with pieces of 2x4 and 4x4 around the edge of the oil pan) to mount the tranny. The Dogleg tranny is pretty damn light, but it’s still a PITA to hold up and try to slide that drive shaft into the clutch hole.
After that, I pretty much did the reverse of pulling the engine/tranny out. It was a PITA to slide the tranny back into the driveshaft yoke so eventually I just unbolted the back from the diff, slid the yoke in and re-bolted the rear.
I also found it quite difficult to connect the engine mounts. Eventually I did it by loosely connecting the passenger side first (less working room). Then I worked on the driver’s side, again with loose bolts except the front lower mount bolt was left off so that the lower mount could be swivelled/lowered to connect to the upper mount. I then used a light crowbar to force the lower mount to swivel back into place to connect the final lower mount bolt. All of this was done while the engine hoist held 95% of the weight.
One other change I made was swap jets on my R1 carbs. These carbs have been running amazing all summer. They offer great performance at any engine speed, fuel efficiency was about the same as my tired OEM Hitachi carb and they had zero synch issues, or dieseling. The 1.6mm DGV jets (ironic that a Mikuni carb uses Weber parts) were sized perfectly for my stock L16. The plugs were a beautiful light tan with a hint of rust tones. For the L20B, I’m using the suggested 1.8mm jets, (edit: after a few hours of driving, they are a shade lighter with more rust than coffee brown than the when on the L16). To swap the jets simply remove the bowl and replace the jet (see pic below).
Start-up
After triple checking the connections I added fluid. For engine oil I used Brad Penn break-in oil. This stuff is only supposed to be used for about 1 hr and then replaced. Their specialty is that they provide lots of zinc to help the flat-tappet cam break-in. Afterwards, I replaced the oil with Rotella 15w-40 diesel oil – again, to ensure there’s lots of zinc to keep the internals happy.
Check that the crank pulley notch is still at TDC and then line up the rotor so that it’s aligned to a plug. In my case, the wires needs to be swapped 180 degrees. There are ways to adjust the distributor (even pulling the oil pump drive) so that no changes are required, but it’s sooooo much easier to just swap wires. Remember, the rotor spins counter clockwise and the firing order is 1-3-4-2.
After the car fired up I played with the throttle for 15 minutes or so to get the temp up. I ended up having coolant leak on the upper gasket of the thermostat housing (carefully, those housing bolts snap real easy), thankfully Andrew came to the rescue with a replacement. I also developed a major coolant leak when the hose for the heat core popped off the block. That was my bad, the block’s piping is slightly smaller than the L16.
The drive
Wow, I was anticipating some improved performance, but there was a lot more torque than I expected. I’m not sure how the L20B was built but I was told there were some mild upgrades and I’m wondering if there’s perhaps ‘medium’ upgrades instead (although the W58 head doesn’t insinuate that).
The R1 carbs are MUCH louder now (in a good way) and I can actually hear them in the cabin for a change. I’ve very pleased that this engine which sat for 3+ years with open ports and all managed to run this well. After a couple of hours of driving I checked the compression and from 1-4 I got 210/185/197/213 psi.
I enjoyed the first couple of driving so much that I decided this was plenty of motor for me and shelved plans for the KA24e R1-carbed winter project. Weight balance is important for me and the extra net 75lbs on the nose (as per DQ engine swap article) over the L20B didn’t seem worth it.
However, after a few hours something became apparent. While the engine is great, that damn dogleg tranny really doesn’t do it any favours. For starters, the first gear is so short that it’s done in an instant with the L20B’s newfound power, secondly all that performance ‘gain’ is lost while I coast trying to perform the annoying up-over-up shift into second (my dogleg is real sticky forcing a left-jab before the ‘over’).
So within a few days of the swap I found myself shopping for a 280zx tranny and realised that it was going to cost me $250-300… about the same cash it will take to finish rebuilding my KA24e which happens to include a short D21 71c tranny already… see where I’m going with this?