It doesn't take much airflow to help out with vapor lock. My radiator sits back from the core support about 1" because its a crappy universal deal. I sealed that gap up last year before drag week and it helped a small cooling problem I had but caused a vapor lock. By opening just the top gap up it allowed enough air to the carb to keep the vapor lock out and fix my highway cooling problem. Its funny how much air moves through that small gap, my air filter had bugs and crap on the front after drag week last year, my car doesn't have a scoop.