The facrory settings for this engine are 3- 4 1/2 out HSN and Flush to 1 out NSN. I always start with 4 1/2 and 1 out and go from there. The leaner you run an engine the hotter it gets. You should run as rich a mixture as you can stand unless you are in a race. Given the same trucks and same skill set of the driver the engine that is running leaner will be faster but will not last as long as the one running richer. If you run with little or no smoke the engine will not last any time.

I write the factory settings for my engines on the inside of the body of my trucks/ cars for reference.