Why is it that when I put a timing light on my '79 Bronco 400m, the mark on the balancer is at 12:00 and my pointer is at 8:00? It cranks and runs good but when I idle in gear with my foot on the brake it wants to die out? 79mightyfine!

 

Someone might have changed something. In any case, I find it exceedingly unlikely that a chain would jump.

 

That far out of time I would think it would have a tough time even starting. I would lean more towards a mismatched balancer installation at some point in the 400M's life.

 

It is also possible to have the balancer rubber slip and move out of position.

 

I was working on a truck one time that the distubuter was stab wrong. At idle with a timming light it kept jumping timing like that. I think the distrebuter was 180 out or something like that. I dont remember how much it was jumping or anything. I really dont know to much about timming. I Just thought I would though that into the thought proceess, as it has happened to me before. GL