Can someone please tell me what size the 18 exhaust bolts are on a 1983 80hp mercury. The old ones are rusted and want to replace them. Thanks in advance.
What are the thread size of them like 1/4 x 20 something like that ? I know they are bigger than the 1/4" as I ordered new water jacket bolts and they were 1/4 x 20 x 3/4".
nc stands for "national corse" yes 18 tpi. It is the standard pitch on 5/16 bolts available almost everywhere. If you look at your other dies/taps you will see that they are all either "nc" or "nf" i.e. fine thread which is 24 in the case of a 5/16.
