u/emiliospace

I installed the head from a different block on my Mazda 323 E3 1.3 Automatic from 1985, its a pre-september model so its easier to say its from 1984 in many online searches i do to solve problems.

The car is running good now when the engine is warm. Performance is very good as well when the engine is warm, just like i knew it from before the head change. Here in the Netherlands ambient in the morning is around 12-15 degrees C (summer). Overnight it stays out and in the morning when i start it, it fires up easily with choke, this is normal behaviour. Carburetor is clean and i dont have any vacuum leaks.

I face 3 problems now:

1. it is prone to stalling when hitting throttle when cold.

Im not sure if this is normal, because i know this also from my older motorcycles. When they are cold they need a few minutes to get up to temperature. But before the head change it was different with the Mazda, now it really needs 2 minutes before i can apply throttle a significant amount. When in winter (ambient 0 degrees C), before the change, it was sensitive when cold for stalling, but i always managed to drive off easily when the choke was engaged.

2. idling

The idle is not consistent. When i start it, it tends to stall if i dont keep the choke or throttle engaged well enough, it comes very precise, i am basically keeping it running with minimum engagement of throttle or choke. My assumption is that my idle is set too low because of this. Before the head change i was able to keep it idling on its own. When i drive it and i stop at a redlight, i put the gear in N when i know i have to wait too long for it to leave it in D. So when in N, the revs shoot up to around 1400 rpm, way too high.

3. finding the right mixture
   currently the mixture screw its on 3 turns out. Finding the sweet spot has been quite hard. It dies at around 1,5 turns out, but finding an unstable setting when going rich is not detectable. At 6 turns out i stopped because the exhaust was getting wet, so i guess thats a signal, but its not ideal. So reading the spark plugs is how i have set it now at 3 turns out.

Hopefully i am missing something very obvious. The performance with a warm engine is excellent, so it feels like i am very close to the right setting.