no gauge? if lick the fin NO JUST KIDDING. put some water on your finger and just barely touch the fin if it crackels and goes away real fast its to hot but if it just evaporates over 2 to 5 seconds its OK. another way is to check your mixture and if you give your truck gas and very little smoke comes out of the exhaust your probably running to lean. To lean To HOT[:@] this is just rule of thumb nothing set in stone [:-]