***Please read through ALL the information before attempting any procedure listed here and before asking ANY questions***
***This tutorial is designed to explain step by step the proper procudures for a COMPLETE tune-up of an engine with points ignition. If you don't know if your engine has a points ignition system, ask!!***
***Some may find this long winded and some steps may seem like common sense. This is designed for someone who has never performed any of the steps described here. If followed correctly you will have completed a proper complete tune-up. Those who have and do perform tune-ups on their own engines will hopefully find some helpful tips here as well***
***This tutorial is about PREVENTATIVE maintenance, something EVERY boater should do, this tutorial will not provide any information about troubleshooting your engine's ignition system***
Okay, you made it here because you were either directed here from the forums, or you are curious about how to tune-up your engine. You must realize that when performing any repair it is necessary to have some patience. If you use common sense and logic, have a full understanding of how the system is supposed to work, and how to properly use the tools required, you will be able to complete this task rather efficiently.
***If you are not familiar with how a points ignition system works, please look at the sticky on how a points ignition system works. Once you understand how the system works it will make it much easier for you to understand what the individual parts do and why you are replacing them.***
There are a lot of runnabilty and no start issues that can be resolved with a little time, a little money, the right tools, some mechanical skills, and a desire to get your engine running well.
Okay, lets go over the tools you will need for your tune-up:
- The correct manufacturers shop manual for the engine you are working on!!
- A set of SAE (standard) wrenches
- A 3/8 drive ratchet with an extension, 3" should suffice
- A 5/8" or 13/16" spark plug socket. Deep well will work but you risk breaking new plugs with these
- A spark plug gapping tool
- Feeler guages
- Dwell meter
- Digital or Analog Volt/Ohm Meter
- Jumper wire (simple wire with alligator clips on both ends)
- Remote start switch
- Timing light
***If you don't have all the tools listed above please realize that your tune-up experience will not go well unless you have the proper tools. This is a great time to add some very handy tools to your collection. You don't have to spend a fortune on a tool set, there are many reasonably priced, high quality tools available. If you have any questions regarding the tools listed here, feel free to post a question in the forums. There are many who will help.***
How to obtain parts:
Your local Mercuiser/Volvo dealer repair shop will be able to provide with all the necessary and PROPER OEM MARINE parts you will need for your tune-up. You must provide them with a serial number/model number for your engine, it is located in one of a few places:
- On the valve cover
- On the flame arrestor cover
- On the engine serial number tag located on the starboard side of the block above the starter (GM) or top of the block at the rear of the motor
- If you cannot find the serial number anywhere, provide them with as much information about your engine as possible - year, model, engine size, # of cylinders, horsepower, etc.
- Spark plugs
- Plug wires (if needed)
- Points set for points ignition (Note: you can purchase tune-up kits that include points set, condenser, rotor, and grease for the distibutor lobes)
- Carb and choke cleaning spray
- Coil - It is not often a coil suddenly stops working but they do wear out. If the coil on the engine looks old and crusty its time for a new one.
Okay, we have our tools and parts, let's head into the shop.
- Gap all the spark plugs to the spec detailed in the maintenance section in the manual
- Remove old spark plugs and replace with new plugs ONE AT A TIME and re-install plug wire boot firmly on new plug. This will ensure you maintain the proper firing order
- Remove coil wire from center post on distributor cap and remove old distributor cap, leaving ALL PLUG WIRES CONNECTED, again this will ensure you maintain proper firing order.
- Remove old rotor.
- Note how the points and condenser wires/copper tabs are insulated and bent to fit snugly inside the distributor body. This must be done on the new parts to ensure they remain insulated from ground! If you are not familiar with the set-up under the rotor, take a picture so you have a reference
- Remove old points and condenser, they are simply screwed to the distributor plate. The wires/copper tabs from each are connected to a screw that is insulated from ground and passes through the side of the distributor body to a wire that goes to the (-) side of the coil. Loosen the screw and nut carefully as not to damage the plastic insulating pieces. Remove the screw and clean screw and nut with wire brush.
- Grease lobed cam in center of distributor.
- Install new condenser to distibutor plate.
- Install new points to distibutor plate and tighten screw.
- Attach one end of the remote start switch to a (+) 12 volt source, battery positive is fine.
- Attach other end of remote start switch to the small yellow/red post on the slave solenoid.
- Bump the engine over until one of the high points on the lobed cam is touching/pointing at the end of the arm on the points.
- Loosen the screw holding the points down and insert a .018" feeler guage between the conact points and lightly press the conact points together.
- Tighten screw holding points to distributor plate.
- Insert screw through ends of properly bent/routed wires/copper tabs from points and condenser through the distributor body with plastic insulators on either side of distributor body. (screw passes through plastic insulators)
- If you are replaceing the coil, disconnect the wires and remove old coil.
- Install new coil and re-attach wires exactly as they were on the old coil.
- Attach ring terminal from wire going to coil (-) side.
- Attach one end of your jumper wire to the coil wire (from center post on coil) and the other end to a good ground (flame arrestor post on carb works fine)
- Turn on your dwell meter and set the zero on it (analog style)
- Attach the positive side of dwell meter to NEGATIVE (-) side of coil.
- Attach the negative side of dwell meter to good engine ground (not the same one you are using for the coil ground)
- Turn ignition switch at helm to "on/run" postion
- Turn your dwell meter to the dwell setting for the number of cylinders your engine has. Some meters have this option and some provide a scale for different cylinder engines on the face of the meter.
- Turn engine over using remote starter switch
- Your meter should be giving you a degree reading for dwell now.
- If your analog meter needle is pegged up or down, there is a short to ground in the points or condenser wire somehwere or your ignition switch is not turned on. Digital meters will give a zero reading or someway to tell you there is no voltage
- Be sure to check the (+) side of the coil to ensure you have positive voltage (4-9 volts (+))
- Once you locate the voltage/grounding issue and get a dwell reading, note what it is and record it.
- Compare the reading to the specification given in the manual for your engine.
- If your reading is with the specifications, great!
- If not you will have to adjust the point contact gap.
- Some distributors have an adjustment screw built in, (awesome!) some do not
- If you have an adjustment screw, simply loosen the clamp screw on the point set a little and turn the motor over and observe your dwell meter.
- As the meter gives you a reading turn the adjustmnent screw SLOWLY and notice the change in the dwell reading.
- You will have to turn the screw either direction depending on which way you need to adjust dwell (it will make sense as you turn the adjustment screw)
- Try to shoot for the middle of the spec range, most V-8's are 26 - 30 degrees but be sure you have the proper spec from the manual!
- If you do not have an adjustment screw, loosen the points set clamp screw slightly until you can move the points with slight resistance.
- You are going to have to do some trial and error as to which way you need to adjust the points depending on whether you need more or less gap. Keep in mind only minor adjustments are needed to increase/reduce dwell.
- Once you have changed the point gap, re-tighten the clamp screw, turn motor over, and observe reading on dwell meter.
- This method may take a few attempts to get the proper dwell setting but be patient, you will get it!
- When you have set the points to the proper dwell, double check that everything is in order, all connections clean and tight!
- Install new rotor on distributor shaft.
- Install new cap on distributor and ensure that it is on the correct way and it is firm and tight!!
- Take the old cap (with the plug wires still connected to it) and ONE BY ONE move the plug wire ends onto the new cap in the SAME position as the old cap.
- Many points ignition caps do not have a number one position on them so it is critical that the plug wires are in the same order!!
- When the plug wires are on the new cap in the proper order you can now install the new wires.
- Again, ONE BY ONE remove the old wires and install the new ones
- Ensure all connections are tight tight tight, you should hear/feel a definite snap when installing wires on the plugs.
- Install new coil wire. Sometimes the rubber boot on the coil tower end is really tight and air gets trapped under it and forces it off. A pick tool underneath the boot will allow air to escape. DO NOT damage the rubber boot!
- Remove the flame arrestor and clean thoroughly with carb and choke cleaning spray.
- Re-install the flame arrestor.
- Now we are ready to run the engine and set timing.
- Double check and ensure all electrical connections are tight.
- Start the engine like you normally would and let warm up.
- Ensure the engine is idling and connect your timimg light to number one cylinder plug wire. Consult the manual if you are not sure which is number one.
- Point the timing light at the timimg grid and engage so it is flashing.
- If the timing is not within spec according to the manual, you are going to have to loosen the distributor clamp down bolt and adjust.
- Shut off the engine.
- The distributor clamp down bolt is located at the base of the distributor where it enters the engine block. It is usually a 9/16" or 1/2" bolt.
- Loosen the clamp down bolt until you can rotate the distributor with slight resistance.
- Re-start the engine and check the timing.
- With your timing light in one hand and the other on the distributor, rotate the distributor slowly either direction and note the change in timing.
- Set the timing to spec and shut down the motor.
- Re-tighten the clamp down bolt.
- Re-start the engine and ensure the timing is correct.
- This is also a good time to check the dwell with the motor running.
- Set your dwell meter up as described above, start engine and observe dwell.
It should still be within spec. If it isn't, re-set the dwell and re-check timing.
- Now you can dial in the carb and set idle speed.
- It is good to have a shop tach to do this but not needed.
- With the boat in the water and tied up nice and snug to the dock, start the engine and let it warm to operating temparture.
- Ensure the choke is fully open, or at least operating correctly.
- Shift the boat into gear (rev or fwd) and ensure the boat isn't leaving the dock (tied up tight!)
- Note the RPM on the tach.
- If the idle RPM is out of spec, turn the idle adjust screw on the carb until the engine is idling within the proper RPM range.
-Once the idle is right, you can adjust the idle mixture screws.
-There may be more than one, consult the manual.
- Turn the screw(s) in counting the number of turns, until the engine starts to falter.
- Turn the screw(s) out counting the number of turns, until the engine starts to falter.
- Turn the screw(s) back in half way between the first and second count of turns.
- Re-check the idle speed and adjust if needed
- If the outside of the carb and choke linkage is dirty clean it with the carb and choke cleaning spray.
- Once you are sure the idle RPM is correct and the engine is idling and warm, re-check timing and adjust if needed.
- Take the boat for a lake test and ensure that the WOT RPM is correct and the engine is running well.