When changing the distribution strap, the crankshaft axis does not carry a key fucking the pinion, it moves and is out of point. If the valves move a lot they touch and death.
You have to use a special Renault user and check very well that it is blocked by turning in the opposite direction to the clock needles.
Those engines mount auxiliary strap or 6pk no ekibocaros that breaks if it is not sulla and lies in the crankshaft and breaks valves.