Is it true lcarnitine helps with angina and exercise tolerance? if so does alc provide same benefit? or does alc affect brain only?

Yes: According to a report by the university of maryland medical center, l-carnitine has been shown to be effective for the treatment of certain symptoms of angina. L-carnitine supplementation may alleviate chest pain allowing angina sufferers to participate in certain exercises. The medical center warns that patients should never self-medicate for chest pain with l-carnitine or any other substance.

Probably true: There is some evidence that acetyl-l-carnitine helps with exercise tolerance in people with angina. There is minimal evidence that it helps healthy people with exercise however. This issue has not been well studied, so even though there is minimal evidence that it helps, that doesn't mean that it doesn't. Here's a nice summary: http://ods.Od.Nih.Gov/factsheets/carnitine-healthprofessional/.