4 pulses or 6 for my tach?

[misterguru]

The tach instructions for my engine don't clearly indicate if I should use 4 or 6 pulses setting.<br /><br />This is a 1977 402 40HP.<br /><br />I have Googled and the result is just as confusing. Anyone know for sure? The serial number starts with a 4.

 

[misterguru]

Re: 4 pulses or 6 for my tach?

Actually the serial is 4730676 which I think is a 1977 model.<br /><br />Thanks in advance.