Spark plug reading

[G72Zed]

What does it mean when the spark plug porcelain is half white and black? I have one that is very distinct and two others not as much but still evident cylinders affected 5,6,7.... all other plugs are consistent. Engine 350 lt-1 2.02 angle point heads. Does not use oil and oil also appears to stay clean. Idle vacuum 16 hcg

The porcelain top section shows the flow/vortex pattern that's happening in the chamber for the most part. The black part could be caused by oil migration & over richness in certain areas of operation.

The first test I do is a cranking pressure test for all cylinders, then a leak-down test afterwards, if everything passes, I go through the electrical/ignition system and change components that need attention. Typically like Cap/rotor/wires and the correct plugs. Then, make sure the carb (if carb'd) is clean and properly calibrated.

By just looking at 1 picture of your plug, this is what I see....again, just my WAG:

1- Oil migration in cylinder - valve seals/rings under decel, or intake/lifter valley leak
2- Rich idle circuit
3- Perhaps bad valve cover gasket
4- side electrode offset.
5- Plug to cold for the application

I can't tell the heat range or timing as the threads are oiled up and the side electrode strap is not visible in the pick. Your WOT ring and mid cruise can't be read as the plug thread body is not cut off and not showing the porcelain, I would go through the steps as I mentioned, and look into a hotter/better plug and start fresh.

 

[COPO]

This may help the OP.

 

[G72Zed]

Yes, that video will help the OP, but he needs to pay attention to my second paragraph and points 1-2-3 and then he can actually start looking at things closely.

As they say, the only thing worse than no data, is bad data.

 

[COPO]

I would also go for a 30 min drive on the highway so the plugs reach self cleaning mode then read them.

 

[1320feet]

What I see, is excessive oil consumption.

 

[Mrnmrssmith]

The porcelain top section shows the flow/vortex pattern that's happening in the chamber for the most part. The black part could be caused by oil migration & over richness in certain areas of operation.

The first test I do is a cranking pressure test for all cylinders, then a leak-down test afterwards, if everything passes, I go through the electrical/ignition system and change components that need attention. Typically like Cap/rotor/wires and the correct plugs. Then, make sure the carb (if carb'd) is clean and properly calibrated.

By just looking at 1 picture of your plug, this is what I see....again, just my WAG:

1- Oil migration in cylinder - valve seals/rings under decel, or intake/lifter valley leak
2- Rich idle circuit
3- Perhaps bad valve cover gasket
4- side electrode offset.
5- Plug to cold for the application

I can't tell the heat range or timing as the threads are oiled up and the side electrode strap is not visible in the pick. Your WOT ring and mid cruise can't be read as the plug thread body is not cut off and not showing the porcelain, I would go through the steps as I mentioned, and look into a hotter/better plug and start fresh.

This may help the OP.

This may help the OP.

The porcelain top section shows the flow/vortex pattern that's happening in the chamber for the most part. The black part could be caused by oil migration & over richness in certain areas of operation.

The first test I do is a cranking pressure test for all cylinders, then a leak-down test afterwards, if everything passes, I go through the electrical/ignition system and change components that need attention. Typically like Cap/rotor/wires and the correct plugs. Then, make sure the carb (if carb'd) is clean and properly calibrated.

By just looking at 1 picture of your plug, this is what I see....again, just my WAG:

1- Oil migration in cylinder - valve seals/rings under decel, or intake/lifter valley leak
2- Rich idle circuit
3- Perhaps bad valve cover gasket
4- side electrode offset.
5- Plug to cold for the application

I can't tell the heat range or timing as the threads are oiled up and the side electrode strap is not visible in the pick. Your WOT ring and mid cruise can't be read as the plug thread body is not cut off and not showing the porcelain, I would go through the steps as I mentioned, and look into a hotter/better plug and start fresh.

Ill be performing a compression test... last year I replaced (hei)cap, rotor, wires, new valve cover gaskets, also installed the original winter intake. Maybe an issue with intake gasket? Plugs are newer also, ac delco 45ts which I believe are the hotter plug, majority of the plugs are very clean. Is there a better brand plug for this engine?

 

[Mrnmrssmith]

Ill be performing a compression test... last year I replaced (hei)cap, rotor, wires, new valve cover gaskets, also installed the original winter intake. Maybe an issue with intake gasket? Plugs are newer also, ac delco 45ts which I believe are the hotter plug, majority of the plugs are very clean. Is there a better brand plug for this engine?

What I see, is excessive oil consumption.

That’s what I was thinking, but no other signs of that. Oil stay clean and level... no smell or blue smoke on start up?

 

[COPO]

Try NGK plugs. They have a cross reference chart. NGK numbers go lower as you move to a hotter plug. Reverse of what other manufacturers do.
https://www.clubplug.ca/static/pdf/ngk-cross-reference-charts.pdf

 

[G72Zed]

Ill be performing a compression test... last year I replaced (hei)cap, rotor, wires, new valve cover gaskets, also installed the original winter intake. Maybe an issue with intake gasket? Plugs are newer also, ac delco 45ts which I believe are the hotter plug, majority of the plugs are very clean. Is there a better brand plug for this engine?

If the comp test and leak down pass, I would suspect a leaking intake gasket from the lifter valley side that is sucking oil, especially on decel/high vacuum.

 

[Z-Life]

its not burning all the fuel, try some R45TSX extended tip plugs and gap them at .060