This is a distributor swap guide for those needing an optical Crank Angle Sensor (CAS) for MegaSquirt, Z31T ECU, or other various EFI systems. The 82-83 280ZX Turbo
distributor is needed, along with the internal CAS and Chopper Wheel (encoder disc). The Nissan VG30E, VG30ET, and VG33E (Z31, Maxima, Pathfinder, Quest, QX4, Xterra) also share the same CAS which can be used to refurbish a warn out 280ZX CAS (see bottom of this post).
The 81 280ZX Turbo distributor does not have an internal CAS, using instead a plate attached to the back of the crank pulley and magnetic sensor mounted on the A/C bracket. Both output the same signal, but the advantage to the 82-83T optical CAS is ease of changing the encoder disc for various EFI setups, and ease of timing adjustment.
Procedure (81T used as example):
- 82-83T Distributor
- 82-83T Oil Pump / Distributor Shaft
- Optical CAS (Hopefully included with your distributor)
- Oil Pump Gasket (Better safe than sorry for $.89)
- If the harness connector is corroded, cut, or otherwise unusable, the 95-99 Nissan Quest uses the same 4-pin CAS distributor connector, and can easily be wired in to the harness (get both sides of the plug).
- Set engine to TDC cylinder #1
- Remove distributor cap and take note (Take a picture!) of the rotor orientation: pointed just down from straight forward. Remove distributor.
- Jack up front of car, chock rear wheels, and use jack stands.
- Lower front sway bar by removing the left and right frame mounts.
- Place oil catch pan under oil pump, remove oil pump bolts (if auto trans, remove 10mm bolt holding ATF line to radiator to allow for more room).
- Carefully pull down oil pump (expect some oil spillage!). Distributor shaft will follow.
- Insert 82-83T shaft into oil pump, aligning the dots.
- Without rotating shaft, carefully insert oil pump, new pump gasket if needed, and shaft back into slots in timing cover. Use a block of wood against the sway bar to hold the pump in place. Check from above that the oil pump shaft is properly aligned. If not, carefully pull down pump and rotate shaft a few degrees in needed direction. Repeat if necessary until perfectly aligned (take your time!!!).
- Re-install oil pump bolts, torque to spec (8-11ft/lb).
- Re-install sway bar brackets, torque to spec (20-27ft/lb).
- Install 82-83T distributor with cap off. Verify that rotor orientation is exactly same as before (reference picture).
- Install distributor 10mm bolts, just loose enough to rotate distributor left and right.
- Install cap, plug in harness connector. Verify that all other connections are tight and engine bay is free of tools and rags.
- Start engine and check timing. Adjust as needed.
If the 280ZXT optical CAS has seen better days, a much newer one can be had for cheap to free at your local junk yard. Some retailers also sell them new for about $79.
M4x.70 bolts and nuts can be found at any hardware store. The only modification is to trim off the alignment
tabs on the newer CAS. Easiest done with a Dremel.
Also for reference, here's a helpful diagram from AtlanticZ
about making sure your cam and chain are properly aligned.
And if you can't get timing within spec, the shaft is most likely a tooth off. A trick to simplify the process is to use vice grips on the top of the shaft so it doesn't drop all the way out when you drop the oil pump. This way you can easily push down, rotate, and pull up to get it to proper alignment, without test fitting and dropping the oil pump. HANDY!!!