Tuning my 340 for high elevation...

Hi guys,

I have a 70 dodge with a 340 engine, performer intake manifold, 650 cfm edelbrock carburetor, electronic ignition, 727 transmission. I live in the bay area which is below sea level. So my car is tuned for the sea level. Every year when I am in Reno Nevada for hot August nights, my car acts up because of the elevation. I was wondering of anyone knows what to do to get the mixture right for the elevation? Do I just lean out the fuel? Or do I also retard or advance the timing? Thanks.