Did a compression check today, took out one plug at a time...went by the manual. Just got this motor off of craigslist...
Cylinders 2,4,6 were around 95-96 lbs
Cylinders 1,3 were 80 lbs
Cylinder 5 is only 50 lbs.
Checked it twice.
The head gaskets and the entire motor looks clean/good/intact...
I have a new used 1981 Johnson 150 HP. It calls for UL77V plugs with no gap. It has other plugs with a gap in it now....don't have the part no. but they aren't surface gap plugs...
What should I use instead of the UL77V and does it make a difference? Why use/spec surface gap plugs?