427 Troubleshooting: Fouled Plugs

427 Troubleshooting: Fouled Plugs

William Mulvey
William Mulvey

December 4th, 2006, 4:40 am #1

Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.

Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.

Paying close attention to the discussions here, we did the following upgrades late this season.

1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.

2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.

3. Timing light confirmed fire at each plug.

At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.

Next steps.

1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.

2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.

3. Installed Pertronix electronic ignition.

We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.

Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.

Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.

If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!

As always, thanks guys, for contributing so much to the Commander community!

Bill
1973 ChrisCraft flushdeck Commander 41
Challenger










<HR WIDTH="100%" COLOR="##666699" SIZE="8">
PHOTO OF THE DAY AWARD (December 5, 2006)

"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!

Paul,
forum moderator

<HR WIDTH="100%" COLOR="##666699" SIZE="8">




Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/m ... 142905538/





Last edited by FEfinaticP on December 8th, 2006, 12:48 pm, edited 1 time in total.
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Paul
Paul

December 4th, 2006, 5:39 am #2

Hope all is well with you and yours.

You say the compression is strong, so that's a fair test of rings and valves.

Right off the bat I'd go after the carbs. I suspect a rich running carb with the automatic chokes being the culprit. My chokes have been wired open, I never use the chokes for starting, as I'm one of those throttle pumpers. I pump as many times as I think I need, some times more if the boat hasn't been run for a couple weeks, you get the idea. I don't like the idea of a 40-year old "automatic" device causing a rich running condition.

Under running conditions have you noticed a gas fume smell (unburned gas), which would be from an overly rich running motor? This would be especially noticed at the dock under idle conditions. If it's not the carb then it's oil that's being burned, which is not necessarily a bad thing. As engines wear, the pistons, rings, and cylinder bores all wear a little and more oil is admitted to the combustion chamber.

In addition, you can get oil dripping slowly down the valve stems too, and this may be corrected with valve stem oil control seals. If you have a high milage motor, you can adjust the plug to burn a little hotter to compensate for this too. A change of oil type and spec may help some too. If it is oil you're burning to cause that soot, you should be seeing some degree of blue smoke on the water. If it is valve stem seepage, I would think you'll see some blue smoke upon startup too. If it's oil that's causing the soot, and it seems to get worse while running around 1000 rpm, then you should be seeing some degree of smoke.

If it's a rich carb, you probably won't see much of anything but you'll smell it if you back into the slip and stand behind the boat.

I think your trusted marina mechanic was on target when he said you didn't need a valve job. You may need some valve stem seals, and it is possible to install those without pulling the head, but it's a hat trick to do it ( you have to be careful not to allow the valve to drop into the cylinder, or then you will have to remove the head. People have been known to stuff closeline into the clinder to act as a buffer.

You have great wires now, the plugs are right, be sure you are using the ballast resistor as required by Pertronix (see the Master Index 427 section on PERTRONIX if you haven't already seen the diagram). If you are sooting over while running around 1000 RPM, I think its the carb, but as with these old boat motors, it could well be a combination of two or three things working together. I'm an optimist!

I'd be interested in hearing some of the other guys chime in on this one, so gentlemen, please fire away when you are ready!

Regards, Paul
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Jerry
Jerry

December 4th, 2006, 5:48 am #3

Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.

Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.

Paying close attention to the discussions here, we did the following upgrades late this season.

1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.

2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.

3. Timing light confirmed fire at each plug.

At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.

Next steps.

1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.

2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.

3. Installed Pertronix electronic ignition.

We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.

Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.

Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.

If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!

As always, thanks guys, for contributing so much to the Commander community!

Bill
1973 ChrisCraft flushdeck Commander 41
Challenger










<HR WIDTH="100%" COLOR="##666699" SIZE="8">
PHOTO OF THE DAY AWARD (December 5, 2006)

"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!

Paul,
forum moderator

<HR WIDTH="100%" COLOR="##666699" SIZE="8">




Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/m ... 142905538/




Ford used an umbrella type valve guide seal, and they have been known to ride up onthe valve stem. They get brittle with exposure to heat and hours, and they can break off. I have heard about the rope trick, but using compressed air works better. This operation can be done while the heads are still on the motor.

Jerry
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Paul
Paul

December 4th, 2006, 7:30 am #4


Hi Bill,

Since the valve seal topic came up, I decided to start a dedicated thread to that particular issue and it can be found here (for your reading and photo viewing enjoyment !)
http://www.network54.com/Forum/424840/m ... 1165216759

Regards, Paul
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Tom Slayton
Tom Slayton

December 4th, 2006, 3:52 pm #5

Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.

Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.

Paying close attention to the discussions here, we did the following upgrades late this season.

1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.

2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.

3. Timing light confirmed fire at each plug.

At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.

Next steps.

1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.

2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.

3. Installed Pertronix electronic ignition.

We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.

Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.

Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.

If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!

As always, thanks guys, for contributing so much to the Commander community!

Bill
1973 ChrisCraft flushdeck Commander 41
Challenger










<HR WIDTH="100%" COLOR="##666699" SIZE="8">
PHOTO OF THE DAY AWARD (December 5, 2006)

"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!

Paul,
forum moderator

<HR WIDTH="100%" COLOR="##666699" SIZE="8">




Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/m ... 142905538/






This is the classic image of a carbon fouled plug due to over rich carb.

Tom


Here's more



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Gary
Gary

December 4th, 2006, 3:57 pm #6

Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.

Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.

Paying close attention to the discussions here, we did the following upgrades late this season.

1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.

2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.

3. Timing light confirmed fire at each plug.

At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.

Next steps.

1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.

2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.

3. Installed Pertronix electronic ignition.

We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.

Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.

Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.

If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!

As always, thanks guys, for contributing so much to the Commander community!

Bill
1973 ChrisCraft flushdeck Commander 41
Challenger










<HR WIDTH="100%" COLOR="##666699" SIZE="8">
PHOTO OF THE DAY AWARD (December 5, 2006)

"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!

Paul,
forum moderator

<HR WIDTH="100%" COLOR="##666699" SIZE="8">




Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/m ... 142905538/




Almost certainly the carb if it's primarily idle/slow speed related.
Adjust the idle air screws for max rpm at idle. Even after a rebuild, mine run best at 1 turn out. A new carb is usually 2 1/2 turns, and that's the way most mechanics will set them.
Over the years, you can get air leaks at the butterfly shaft seals. This will also cause a rich condition. If that's the problem, it's time for a new carb.
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Joined: March 21st, 2006, 10:43 pm

December 4th, 2006, 7:05 pm #7

Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.

Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.

Paying close attention to the discussions here, we did the following upgrades late this season.

1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.

2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.

3. Timing light confirmed fire at each plug.

At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.

Next steps.

1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.

2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.

3. Installed Pertronix electronic ignition.

We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.

Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.

Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.

If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!

As always, thanks guys, for contributing so much to the Commander community!

Bill
1973 ChrisCraft flushdeck Commander 41
Challenger










<HR WIDTH="100%" COLOR="##666699" SIZE="8">
PHOTO OF THE DAY AWARD (December 5, 2006)

"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!

Paul,
forum moderator

<HR WIDTH="100%" COLOR="##666699" SIZE="8">




Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/m ... 142905538/




Regarding those fouled plugs, I also had the same problem in both my 427s. Originally, I thought I may have too much lead additive in my tanks. I remember that caused my brother's '63 Fairlane to foul plugs for awhile. After running last summer without any lead additive, I still fouled plugs.

Just a couple of months ago, and for totally separate reasons, I checked the timing on both engines. Both were off the mark. After making proper adjustments, I seemed to have accidentally fixed the fouling plugs problem in both engines. As already stated, many things can cause plugs to foul, but in my case, setting the timing per the spec seems to have fixed my problem.

Mike Frazier
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Joined: March 7th, 2006, 1:21 am

December 5th, 2006, 12:11 am #8

Hope all is well with you and yours.

You say the compression is strong, so that's a fair test of rings and valves.

Right off the bat I'd go after the carbs. I suspect a rich running carb with the automatic chokes being the culprit. My chokes have been wired open, I never use the chokes for starting, as I'm one of those throttle pumpers. I pump as many times as I think I need, some times more if the boat hasn't been run for a couple weeks, you get the idea. I don't like the idea of a 40-year old "automatic" device causing a rich running condition.

Under running conditions have you noticed a gas fume smell (unburned gas), which would be from an overly rich running motor? This would be especially noticed at the dock under idle conditions. If it's not the carb then it's oil that's being burned, which is not necessarily a bad thing. As engines wear, the pistons, rings, and cylinder bores all wear a little and more oil is admitted to the combustion chamber.

In addition, you can get oil dripping slowly down the valve stems too, and this may be corrected with valve stem oil control seals. If you have a high milage motor, you can adjust the plug to burn a little hotter to compensate for this too. A change of oil type and spec may help some too. If it is oil you're burning to cause that soot, you should be seeing some degree of blue smoke on the water. If it is valve stem seepage, I would think you'll see some blue smoke upon startup too. If it's oil that's causing the soot, and it seems to get worse while running around 1000 rpm, then you should be seeing some degree of smoke.

If it's a rich carb, you probably won't see much of anything but you'll smell it if you back into the slip and stand behind the boat.

I think your trusted marina mechanic was on target when he said you didn't need a valve job. You may need some valve stem seals, and it is possible to install those without pulling the head, but it's a hat trick to do it ( you have to be careful not to allow the valve to drop into the cylinder, or then you will have to remove the head. People have been known to stuff closeline into the clinder to act as a buffer.

You have great wires now, the plugs are right, be sure you are using the ballast resistor as required by Pertronix (see the Master Index 427 section on PERTRONIX if you haven't already seen the diagram). If you are sooting over while running around 1000 RPM, I think its the carb, but as with these old boat motors, it could well be a combination of two or three things working together. I'm an optimist!

I'd be interested in hearing some of the other guys chime in on this one, so gentlemen, please fire away when you are ready!

Regards, Paul
Thanks again, guys, for all the on-line diagnosis. The consensus seems to lead to carb issues, so hopefully this winter's rebuilds will cure the problem.

Here are a few answers to the questions brought up in the threads:

1. No blue smoke has been seen and I've looked for it. Also, no gas smell has been noticeable. Exhaust water does occasionally have a slight floating rainbow, but then I've never seen a marina basin without it. Also, NO oil consumption.

2. The only noticeable symptom in addition to the black soot on the plugs has been a blast of soot fired out the exhaust if I've changed spark plugs. That stuff floats!

3. Based on prevous posts regarding those automatic chokes, I agree that it's unlikely they're working right after 33 years. Time for them to go away.

And a question to Jerry . . . if those valve guide seals have actually ridden up on the valve stem, would the mecahnic have noticed that, or are they still out of sight with the valve covers off?

Thanks again, guys . . . I will follow through with a report in a few short months when the boat can float again in an ice-free Seneca Lake. All of the advice and suggestions are awesome and appreciated.
Bill M
1973 CC Commander
Challenger

PS: I hope Tim Toth sees my pic of my new iginition wiring . . . it's a challenge matching his craftsmanship.
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Tim T
Tim T

December 5th, 2006, 3:43 am #9

Bill,
Good looking detail job on your plug wires !
I knew you would "see" the performance increase with an ohm-meter .Make sure you do not have an air leak on the choke heat pipe where it attaches to the exhaust manifold and the choke adjustment knob .
Your engines are fine ,just re-build the carbs during the off-season ,replace the plugs with a " projected nose" style plug,Champion -RF9yc or Splitfire - SF4E .,set timing to 10.5 with a digital dial-back light and you will be set .
Tim T
Sandusky ,Oh
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Jerry
Jerry

December 5th, 2006, 11:32 am #10

Thanks again, guys, for all the on-line diagnosis. The consensus seems to lead to carb issues, so hopefully this winter's rebuilds will cure the problem.

Here are a few answers to the questions brought up in the threads:

1. No blue smoke has been seen and I've looked for it. Also, no gas smell has been noticeable. Exhaust water does occasionally have a slight floating rainbow, but then I've never seen a marina basin without it. Also, NO oil consumption.

2. The only noticeable symptom in addition to the black soot on the plugs has been a blast of soot fired out the exhaust if I've changed spark plugs. That stuff floats!

3. Based on prevous posts regarding those automatic chokes, I agree that it's unlikely they're working right after 33 years. Time for them to go away.

And a question to Jerry . . . if those valve guide seals have actually ridden up on the valve stem, would the mecahnic have noticed that, or are they still out of sight with the valve covers off?

Thanks again, guys . . . I will follow through with a report in a few short months when the boat can float again in an ice-free Seneca Lake. All of the advice and suggestions are awesome and appreciated.
Bill M
1973 CC Commander
Challenger

PS: I hope Tim Toth sees my pic of my new iginition wiring . . . it's a challenge matching his craftsmanship.
Bill, your mechanic would probably not have seen them. I doubt if he even looked under the valve covers. Even if he did, he might have missed the backside of one that was broken. When these go out, you generally know by looking in the rear view mirror, because you are smoking down the neighborhood.

Jerry
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