clomid raises your testosterone levels when your body has low test, or normal test. when your on cycle and you have lots of test/androgens in your system, clomid will not be able to cause your body to start test production. the way clomid works is through one of two feedback loops.. when the body senses low test or low estrogen, it boosts test. so clomid makes your body think it has low estrogen, which causes a boost in test. but when you already have high test you body recognizes that and it doesnt matter how low your estrogen gets (or how low you make it think your estrogen has gotten), you body wont start up test production.
hcg bypasses the brain and body and go directly to the testicles, demanding that they start producing test + sperm.