Spark plug wire order

[hannahbear]

How do know which plug wire goes to which spark plug? If I suspect they're in the wrong order and I change the order and it's not right, will it hurt anything to start it to see if it runs better?<br /><br />Thanks,

 

[hannahbear]

Re: Spark plug wire order

Oh yeah, It's a 3.0LX Mercruiser....<br /><br />Thanks again,

 

[ScottRock]

Re: Spark plug wire order

Hannabear- Youve' probably already thought of this but if you have a manual on the motor it will tell you firing order and should actually give you a diagram showing the order(cylinder #)right on top of the distributor. Sorry if I am stating the obvious. Hope it helps.

 

[hannahbear]

Re: Spark plug wire order

No, it's not obvious to me. The wires in the diagram in the book I have look to be going to different cylinders, if I'm looking at it correctly. I guess my fear is that I'm not. If I'm not and I change them, will it hurt anything if I try and start it.<br /><br />Thanks,

 

[hannahbear]

Re: Spark plug wire order

I found the firing order. It says 1-3-4-2, but what does that mean and will I hurt anything if I plug them in wrong?

 

[ScottRock]

Re: Spark plug wire order

Hannabear- I am assuming you have a straight 4 in your boat(all four plug wires on one side of the block.) The firing order(1,3,4,2) should start with the #1 cylinder starting in the bow end of the motor and the 2 cylinder in the transom end of the motor. If you have a V-shaped block I havent a clue except 1 & 3 will be on one side and 4 & 2 will be on the opposite with both 1 and 4 being in front(bow side) and 3 & 2 in the back. Running the boat(if the wires are on the wrong cylinder's)will only hurt it if you let it run continuously. Believe me, you'll know right away if they aren't in the right order. It will miss like crazy. Just shut it off and adjust the order. Hope it helps. Of course if you ever need to change out wires down the road, it is always better to do one at a time. Sorry bout the long reply.

 

[ScottRock]

Re: Spark plug wire order

Hannabear-I think I had a brain F--- about the cylinder order(I know I DID!) While your firing order from the distributor is 1-3-4-2, your piston order on the block will be 1-2-3-4 with 1 in the bow side and 4 in the transom side. If you have a v-block it is the same 1 & 2 and 3 & 4. It really depends if it is a Chevy, Ford. etc as to which side the 1 & 2 pistons and 3 & 4 pistons are on. Again, you wont hurt the motor if it is in the wrong order. You'll know it by the way it sounds. Just shut it off and try again. Sorry for the misinformation the first time. It is past my bedtime.

 

[hannahbear]

Re: Spark plug wire order

OK... Thanks. That helps. At least I know I if I mess up I won't blow anything up. It's a four cylinder, all on the same side. How do I match the cylinders up with the distributer cap?

 

[jee70611]

Re: Spark plug wire order

Hannahbear,<br /><br />To tell where they go on the distributor, there should be a "1" near the post where the number 1 wire goes. Next, take the cap off and tap the motor over with the starter for a second to see which way the rotor under the cap turns. If it turns clockwise, put the wire from the #1 sparkplug on the post indicated by the "1." Then, put the #3 wire on the next post going in a clockwise direction, then the #4, then #2. If the rotor turns counter-clockwise, the procedure is the same. Just put the wires on in a counter-clockwise rotation. Hope this helps. Good Luck!<br /><br />James

 

[ScottRock]

Re: Spark plug wire order

Look at your engine manual. The diagram with the firing order on your distributor should show you that. It should actually have a little picture on it showing the placement of 1,3,4,&2 on the dist. cap. Attach the first wire to #1 on the distributor and then take it down to the #1 piston (bow side of motor.) Follow the same procedure with 3,4,& 2. Just remember that the pistons are in order 1,2,3,&4.

 

[hannahbear]

Re: Spark plug wire order

Thanks for all of your help. I think I've got it, but there is no number 1 on the cap to show the starting point and my book doesn't say. Is there any other way to tell which one is the starting point?

 

[jee70611]

Re: Spark plug wire order

Yes Hannahbear there is another way. I'm gonna warn you though, it isn't as easy as the other method. You could do it by taking all of the plugs out except the number one plug and turning the engine over until you feel a lot of resistance. The point of this is that you want the number one cylinder to be at top dead center on the compression stroke, not exhaust/intake stroke. I would recommend turning it over a few times to get the feel of what you're looking for. You will know what you're feeling for when you feel the resistance. I would get some sort of a breaker bar with a socket on the crankshaft pulley bolt. Also, make sure that the igition key is off. You don't wanna get shocked or start a fire from the coil sparking to the block. Once you know you are on the compression stroke, look at the ignition timing plate by the crankshaft pulley. There should be some sort of marking on the harmonic balancer that you can line up with "0" or "TDC" etc. Once you get the number one cylinder at top dead center, take the cap off and look where the rotor is pointing. The post that is the closest to the rotors tip is the number one post. Then you can just follow the same instructions I gave before. Good Luck!<br /><br />James

 

[hannahbear]

Re: Spark plug wire order

Thanks alot for all your help.....

 

[Boatist]

Re: Spark plug wire order

Jee way will work very well. I dissagree that it will not hurt anything if you get it wrong. You probably would not get it to start if wrong but could blow a hole in a piston or force the engine to turn backward. Two more ways to find top dead center for number one. Take an old spark plug and break the center out of it. Make sure nothing loose left in plug that could fall into cylinder. Now put a ballon over the plug and a rubber band around it to hold ballon on the plug. Screw it into number 1 at the front of the engine. Remove all the other plugs so engine is easy to turn. Now turn engine by hand until the ballon blows up to it largest size. You are now at top dead center for number one. Line on balancer should line up with zero on degree plate. Follow Jee instructions and put you wire on. The 3.0 is a chev 181 c i straight four cylinder number one in front them 2,3,4 in the back. Last way is very easy just pull the plugs and put your finger in number one now turn by hand when it starts the compression stroke it will blow your finger out until you reach top dead center then it will try and suck your finger in. Line up the degree wheel and you have got it. Line on the balancer will line with the degree plate two times. One when the exhaust and intake valves are open so no compression or suction. Second on the compression stroke when both intake and exhaust valves are closed so when the piston moves up or down only place for air to go is out the spark plug hole.<br /><br />Just for info V blocks Number one will be in front on the Port side next one back will be number 3 then 5 then 7. Number 2 will be at the front on the Starboard side then 4, 6, 8 at the back. Port side will have all the odd numbers and the Starboard side all the even numbers.

 

[jee70611]

Re: Spark plug wire order

Hannahbear,<br /><br />Just curious as to whether you got it going? Boatist, that balloon trick is great. I never would've thought of that. Thanks. Let us know how it goes Hannahbear.<br /><br />James