What does engine code 12 signal?

Code 12 - not receiving the signal from the distributor pickup coil, but this can be because the timing chain let go FYI, how does it sound when cranking, like flipper? It also sounds like the valve is too tight which can put extra strain on the timing chain. If you upload a video of the engine cranking, I can tell you for sure if the timing belt is good or not. If the timing chain is okay, I would get a rebuilt ignition distributor which you can find on Amazon for $77.00.

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Let us know how it goes.

Thanks for the advice. I checked under the valve cover, and the timing chain is still solid. When I gapped the valves, I went with the Yota tech advice of making them slightly tighter 0.007 instead of 0.008" and 0.011" instead of 0.012".

Getting a new distributor from O'Rielly's because I need this rolling asap. Will adjust the gaps accordingly.

Update: The timing chain snapped. My sorry self managed to drop a 16mm bolt into the engine last time the valve cover was off, and I didn't inspect things soon enough. Sitting right there on the bottom gear. I'll be taking the cover off and putting a new chain in ASAP.

Don't too hard on yourself, it happens. I need to say there is a good chance you have a bent valve or two FYI. Let me know if you need help with any of the repair.