mixed up spark plugs

[lhall8]

I am new to boats, and just got a 1986 sylvan with I think a 4.3 omc cobra engine. However, the spark plug wires were not on the engine when I recieved. I found the firing order on the engine, but I do not know which cylinder is firing. So I do not know where on the distributer to place the first plug wire to start the firing order correctly. Any help is greatly appreciated.

 

[Don S]

Re: mixed up spark plugs

Pull #1 spark plug, and turn the engine over by hand untill you feel pressure building in that cylinder (put your finger over the hole and feel the pressure) then continue turning till the timing mark on the vibration dampner is on the 0 mark on the timing marker. You are now at #1 TDC.<br />From there, pull the distributor cap off and see where the rotor is pointing. That is number 1 wire. Then put the wires in the distributor going clockwise 1-6-5-4-3-2.<br />Note: Port head is #1 in front, then 3 then 5<br />Starboard head is #2 in front, the 4, then 6.

 

[rodbolt]

Re: mixed up spark plugs

a reminder<br /> make sure its the mark just after your finger gets blown off the hole. it will be a TDC twice for a complte cycle. after the pressure blows on your finger and you continue to TDC you are now at top dead center(TDC) on the compression stroke. do what DonS says and it works. has for many years and is easier than pulling a rocker cover and watching an intake valve.

 

[jlshields]

Re: mixed up spark plugs

Or...just look on the cap for the number '1' embossed on it. May want to check the timing also unless you know they were replacing the wires only, not the distributor.

 

[Don S]

Re: mixed up spark plugs

jlshields <br />Not all caps have a #1 marked on them, and if the distributor was removed by someone and put back in wrong, that number would be meaningless. That is why you get the engine up on #1 TDC and locate where the rotor is pointing. If it happens to be where #1 is marked on the cap, then all is fine. I have found about 50% of the boats I have worked on are not on the #1 mark.

 

[Mahoney]

Re: mixed up spark plugs

Another tip, especially if your wires are of equal length is to mark the spark plug end of the wire with the corresponding cylider it is attached to. Nothing is more frustrating than pulling wires and plugs repeatedly(and if you are messing with ignition, you will)then having to track those wires back up to the cap everytime.