making sure the engine is in tune, no vacuum leaks, and the timing advance is working are biggies. hotter range plugs and lighter weight springs in the distributer advance mechanism is also helpful. aftermarket air cleaners are greatly better than stock units, but alot of guys insist on stock breather assemblies at the expense of engine efficiency. switching to an electric fan will help. that stock fan eats power. then look at the brakes to insure they don't drag, and----the easiest thing of all---check and maintain tire pressure. is that of any help? good luck, and if you do any of those things i suggested and it works, please post the results.
