D16Y8 Engine ignition timing when using OBD1 ECU (ie: P28, etc.)

There's a lot of misinformation about how to set the ignition timing on a D16Y8 engine when using an OBD1 ECU (ie:  One of our P28/S300 ECU setups and similar).

The differences timing-wise between the D16Z6 and D16Y8 are in 3 different areas:

1.  The crankshaft pulley timing marks.  The D16Z6 has a mark at TDC and one at 16 degrees BTDC.  The D16Y8 has a mark at TDC and one at 12 degrees BTDC.
2. The camshaft pulley key-way alignment.  The keyway slot in the end of the cam where the camshaft pulley goes on is clocked different.  As long as you don't mis-match cam and cam gear between the two engines this is irrelevant.
3. The ECU's base ignition timing.  The D16Z6 OBD1 ECU uses 16 degree base timing, thus the reason on the pulley is at 16.  The D16Y8 ECU uses 12 degree base timing, thus the reason that pulley is at 12.

When running a D16Y8 engine (completely stock engine, no cam changes, etc.) on the OBD1 ECU, all you have to do is use an adjustable timing light when setting the timing.  Set base timing at 16 degrees and just know that the mark on the pulley is at 12, not 16.  That's it 🙂 

The D16Y8 engine's ECU uses 12 degrees simply for emissions.  Honda did this to try to bring down emissions at idle.

When timing is set properly, your distributor should be roughly in the middle of the range of adjustment.