If sparkplugs could talk

[tmcdonagh]

Now that I am close to retirement, I have decided to take on tasks I thought I did not have the time for as a busy working slob. I tacked the gas filter and oil change. I barely avoided creating a superfund site with both operations. I then took on the spark plug change out. It was a crusty nasty mess but I did not break any on the way out. Please see the pictures of the business end of the plugs. They are arranged from 1 through 4. The last two picks are of 1 then 4. What are your thought?
A little history, she has been inning a bit rough this last year with the engine cutting out unexpectany and has been a rough starter.

Thoughts?

Tom

[tenders]

I'm not an expert on spark plugs but what those tell me is that (1) you have had water in your engine room that has rusted the outside of the plugs (ie, that rust could be an engine problem if it is the head that has leaked that water), (2) the first two plug tips look just about a perfect "toasty" brown, and (3) it is not unusual for the last two plugs to show signs of a richer mix.

So my read would be that you need new plugs, make sure the plug wells are free from water, and probably look to the carb, fuel, or ignition for causes of ill-running.

[Dave Neptune]

Talking plugs

Tom, the plugs don't actually talk but they do leave clues to be read.

First, the lack of color on the electrode porcelain indicates a plug whose "heat range" is to hot as there is very little deposited, dark or light. A cooler plug will make more power, run smoother and allow deposits to coat the ceramic which is nothing more than a heat sink.

The darker color on the ground indicates a pour burn inside the cylinder. This poor burn most likely is the timing is to far advanced.

The color that shows is OK for "economy" however more power and cooler running engine needs a bit more color like Jerry mentioned.

Try a set of stock range plugs for a couple of hours and take another "read" of the color. You want to see the beige~tan on the porcelain and about the same on the ground albeit a bit darker. Set the gap to .030 with points and if you run an EI go to at least .035/. The additional gap will idle smoother and start faster too, a big advantage of the EI systems.

Do you know if the plugs shown are in the same heat range or did you go hotter for some "fix-it" reason?

When installing the plugs give the entire outside of the plug a thin coat of dielectric silicone. This aids in both rust prevention and heat transfer through the boots by maintaining "contact' for good heat transfer and the boots won't tear when removing.

NOTE the boots are a big part of the "heat sink" equation related to plug running temps.

Dave Neptune

[RobH2]

Awesome info Dave...!

[tmcdonagh]

Tom, the plugs don't actually talk but they do leave clues to be read.

First, the lack of color on the electrode porcelain indicates a plug whose "heat range" is to hot as there is very little deposited, dark or light. A cooler plug will make more power, run smoother and allow deposits to coat the ceramic which is nothing more than a heat sink.

The darker color on the ground indicates a pour burn inside the cylinder. This poor burn most likely is the timing is to far advanced.

The color that shows is OK for "economy" however more power and cooler running engine needs a bit more color like Jerry mentioned.

Try a set of stock range plugs for a couple of hours and take another "read" of the color. You want to see the beige~tan on the porcelain and about the same on the ground albeit a bit darker. Set the gap to .030 with points and if you run an EI go to at least .035/. The additional gap will idle smoother and start faster too, a big advantage of the EI systems.

Do you know if the plugs shown are in the same heat range or did you go hotter for some "fix-it" reason?

When installing the plugs give the entire outside of the plug a thin coat of dielectric silicone. This aids in both rust prevention and heat transfer through the boots by maintaining "contact' for good heat transfer and the boots won't tear when removing.

NOTE the boots are a big part of the "heat sink" equation related to plug running temps.

Dave Neptune

Thanks Dave!. Oh, plugs don't talk! I thought they were not listening.

I replaced the plugs with Champion RJ12C's and gapped that @ 0.04 as suggested on the forum. I will go back and remove, regap at 0.03 as I don't have the electronic ignition yet and spray with the dielectric silicone. Are there better spark plug wires for heat dissipation?
The plugs were leftover by the previous owner and I have no knowledge of why they were installed.

After installing a new gas filter and plugs she still runs rough for 1-2 minutes, coughing, stumbling and backfiring. She settles down nicely after that time. If I restart her right away, it runs normally. If she sits for 4-6 hours or overnight, the histrionics return. I have not been able to pressure test her on the water as of yet.

Thanks again!

[Boat]

your timing looks off to me.

[tmcdonagh]

The Saga continues..

Returned to the boat this weekend armed with all the suggestions and best wishes.
Here's what I did.

Tested compression on all cylinders and they all checked out at ~90 PSI.
Re-gapped spark plugs from 0.04 to 0.03 as suggested.
Injected an ounce or two of MMO into each cylinder and allowed to sit for 30 minutes after a few engine cycles.

Engine stated very rough after 10-15 attempts. Coughed, backfired and sputtered for 2 minutes and would not tolerate choke without stalling. After the 2 minutes or so she settled in and I could run the throttle up to max with no problem. Exhaust smoke was minimal but there seemed to be a bit more oil in the water than I generally notice. Applying a load to the engine by putting it into forward gear caused the engine to cough, backfire, sputter and stall.

I pulled the spark plugs and found plugs 1 and 3 carbonized and sooted while 2 & 4 were clean.

No Joy.

Any suggestions?

Thanks, Tom

[JOHN COOKSON]

Is the prop clean and free of fouling?

TRUE GRIT

[tenders]

Are you certain the plug wires are run to the correct plugs in 1-2-4-3 order coming off the distributor? If you can get it running and idling again, pull off one plug wire at a time and confirm that each one is firing. She may not be "firing on all cylinders," so to speak.

Is the exhaust free and clear, ie, not blocked with failing hose internals or a kink? The engine could be choking on its exhaust, which can get worse on loading (ie putting it into gear).

Are the advance weights and springs free to move smoothly underneath the distributor?

[tmcdonagh]

Prop free?

Is the prop clean and free of fouling?

TRUE GRIT

Pretty sure John. Prop is clean as she was just splashed and nothing is evidently wrapped around the prop.

Thanks,

Tom

[tmcdonagh]

Is the prop clean and free of fouling?

TRUE GRIT

Are you certain the plug wires are run to the correct plugs in 1-2-4-3 order coming off the distributor? If you can get it running and idling again, pull off one plug wire at a time and confirm that each one is firing. She may not be "firing on all cylinders," so to speak.

Is the exhaust free and clear, ie, not blocked with failing hose internals or a kink? The engine could be choking on its exhaust, which can get worse on loading (ie putting it into gear).

Are the advance weights and springs free to move smoothly underneath the distributor?

Hi Tenders,

Those are all great questions.

WRT The exhaust, I am not sure and will have to check.
The wiring appears correct. I will check spark on all cylinders too.
Digging into the innards below the distributer scares me but it sounds like a dark place I may have to go.
Are the symptoms and remedies you suggest consistent with the motor not liking any choke?

Thanks,

Tom

[JOHN COOKSON]

After installing a new gas filter and plugs she still runs rough for 1-2 minutes, coughing, stumbling and backfiring. She settles down nicely after that time. If I restart her right away, it runs normally. If she sits for 4-6 hours or overnight, the histrionics return. I have not been able to pressure test her on the water as of yet.
Thanks again!

This sure sounds like a sticky valve(s) to me. If you were able to run the engine at cruise RPM for an hour it might unstick it. Do you use MMO in your gas? Some* recommend outboard motor oil in the gas to unstick valves. I don't know the exact recipe.
*I think it was Dave N.

TRUE GRIT

[tmcdonagh]

This sure sounds like a sticky valve(s) to me. If you were able to run the engine at cruise RPM for an hour it might unstick it. Do you use MMO in your gas? Some* recommend outboard motor oil in the gas to unstick valves. I don't know the exact recipe.
*I think it was Dave N.

TRUE GRIT

Hi John,

I treated the cylinders for about 1/2 hour with MMO and noted no improvement. I did not try it as a gas treatment as of yet. Thanks, it is now on my list.

Tom

[JOHN COOKSON]

Hi John,

I treated the cylinders for about 1/2 hour with MMO and noted no improvement. I did not try it as a gas treatment as of yet. Thanks, it is now on my list.

Tom

MMO into the cylinders probably did not get the MMO to the valve area.
A compression test on a cold engine would probably give you the most information.

TRUE GRIT

[tmcdonagh]

MMO into the cylinders probably did not get the MMO to the valve area.
A compression test on a cold engine would probably give you the most information.

TRUE GRIT

Thanks John, I will try adding it to the fuel. Compression was tested on the cold engine and found to be around 90 psi for all cylinders.

Tom