donnie g, your going to have to throw most of what people say out the window... your at 4500ft this is going to make you tune your car alot different then most.. first the timing will need to be alot higher then most so you start to burn the fuel alot sooner ....i see you have a sbc most of the time a sbc will run with 15deg at idle to full adv of about 36deg.. you need to put it 23-27 at idle and may even have to go 40-42 total.. as for fuel start leaning it out alot what you may think is to far is more then likely not enough..i have raced at mile high dragway and the tune up there was so far off i just changed carbs and the timing was 13deg higher then anywere else i ran... good luck with it.