[chevybuilder18]

Nice! I don't mean to be discrimitive to the edelbrock carbs but I hear a lot of people have issues with it back firing through the carb, if you got a timing leak, it could also mean your vacuum hoses are colapsing, the stiffer hoses is what I would use especially with the set up you have now. And make sure your lines don't have kinks in them. The fact that you can advance the dizzy and it get better is scary, I have Always retarded timing to get rid of the spark knock or back fire