Had a 2n that had a clacking or knocking noise when warm and under load,also had a miss.Decided to open it up and have a look see,here is what I found.
1.Small crack in head
2.4 teeth missing from cam gear.
3.Broken spring on exhaust valve cyl.#3
Did a visual check of the rod bearings,cam shaft,main bearings and wrist pins.To my very untrained eye they all looked OK.
I removed and cleaned valves and installed all new springs,checked tappet clearance.Installed good used head and new gasket.Installed good used cam gear.I then buttoned the engine back up and fired it up,I still have a pronounced miss but haven't heard the knock yet.Checked spark,have nice blue spark jumping at least a 1/4". Rechecked timing and points of dizzy,looked to be spot on.Decided to pull plug wires one at a time,pulled #4 and the engine did nothing different,sounded exactly the same as it did with 4 plugged in. Pulled #3 and the engine fell flat on it's face.Checked the plugs after running 1,2,3 all dry and clean,#4wet and dirty looking.Repalced plug and wire,no diff.Now I'm thinking something is wrong with #4,did comp test...95lbs,all other cyls 95 to 100 lbs.
How can I have good spark,good compression and good fuel flow and still no firing of that cylinder???
Can you help a brother out???
Dan
1.Small crack in head
2.4 teeth missing from cam gear.
3.Broken spring on exhaust valve cyl.#3
Did a visual check of the rod bearings,cam shaft,main bearings and wrist pins.To my very untrained eye they all looked OK.
I removed and cleaned valves and installed all new springs,checked tappet clearance.Installed good used head and new gasket.Installed good used cam gear.I then buttoned the engine back up and fired it up,I still have a pronounced miss but haven't heard the knock yet.Checked spark,have nice blue spark jumping at least a 1/4". Rechecked timing and points of dizzy,looked to be spot on.Decided to pull plug wires one at a time,pulled #4 and the engine did nothing different,sounded exactly the same as it did with 4 plugged in. Pulled #3 and the engine fell flat on it's face.Checked the plugs after running 1,2,3 all dry and clean,#4wet and dirty looking.Repalced plug and wire,no diff.Now I'm thinking something is wrong with #4,did comp test...95lbs,all other cyls 95 to 100 lbs.
How can I have good spark,good compression and good fuel flow and still no firing of that cylinder???
Can you help a brother out???
Dan