0.020 in.
The points gap on a Merc 40 4hp is .020
To find out how old a 4HP Mercury outboard is, you can look at the label on the transom bracket, where you will see a two digit number giving you the year it was built.
A 4hp Mercury outboard requires a 50:1 fuel to 2 cycle oil mix.
Johnson 4hp outboard bj4brcud
Mine is a 2000 model and it has an NGK R BPR7HS10
The serial number 5591101 on a Mercury 4hp outboard motor indicates that it was manufactured in 1982. Mercury outboard motors typically have a serial number system that correlates to specific production years, and this number falls within the range for that year. For precise identification, you can also check the manufacturer's resources or consult a Mercury dealer.
You may have mistaken the '1' for a '2'..if your engine is a 4hp 2 cylinder it dates from 1978.
A 1998 model 4hp Merc outboard runs on a 50:1 fuel to oil ratio. This works out to roughly one pint of 2cycle oil to six gallons of fuel.
Jew
1969
1969.
The 4WF69B model, 4hp Johnson, would be a 1969 year model.