How does this spark plug look like to you?

[TylerW]

Hey guys:

Been working on a slight drivability issue. Very likely need to tweak some carb jets one way or the other. Stock low compression engine, pulled this plug after a mix of city and highway driving. How does the jetting look to you? Thanks.

 

[circlepilot]

IMHO, clean, maybe a little on the lean side. Reading 101: How to Read Your Spark Plugs - OnAllCylinders

 

[circlepilot]

 

[yellow rose]

Hey guys:

Been working on a slight drivability issue. Very likely need to tweak some carb jets one way or the other. Stock low compression engine, pulled this plug after a mix of city and highway driving. How does the jetting look to you? Thanks.

View attachment 1715318858

Either the plug is too hot or you have too much timing on it. What engine is it? And what plug is it. It certainly isn't lean at idle and a cruise. Can't tell about WOT.

Those picture charts are worthless.

 

[jimjimjimmy]

Either the plug is too hot or you have too much timing on it. What engine is it? And what plug is it. It certainly isn't lean at idle and a cruise. Can't tell about WOT.

Those picture charts are worthless.

I agree timing is high and fat idle .

 

[circlepilot]

Either the plug is too hot or you have too much timing on it. What engine is it? And what plug is it. It certainly isn't lean at idle and a cruise. Can't tell about WOT.

Those picture charts are worthless.

My assumption was he had a fuel related question by mentioning "jets." I read spark plugs (aircraft...not a big difference) routinely as apart of my inspection process. Not trying to dispute a timing problem, (aircraft engine timing is "set in stone" by the eng. data plate, i.e. 25 deg. TDC means just that) but his spark plug pictured (in relation to fuel) shows to be a "little" on the lean side, "if" his fuel/air mixture is what is causing his "drivability" issue. Just trying to help.

 

[yellow rose]

My assumption was he had a fuel related question by mentioning "jets." I read spark plugs (aircraft...not a big difference) routinely as apart of my inspection process. Not trying to dispute a timing problem, (aircraft engine timing is "set in stone" by the eng. data plate, i.e. 25 deg. TDC means just that) but his spark plug pictured (in relation to fuel) shows to be a "little" on the lean side, "if" his fuel/air mixture is what is causing his "drivability" issue. Just trying to help.
View attachment 1715319178

The middle plug in this picture is pig fat at idle and rich at a cruise. The plug on the left may be a touch lean but that's hard to see in a picture.

If you have any ignition at all, you will have mostly white porcelain with a .060-.080 wide fuel ring at the bottom. Sometimes, you get stuck running slightly rich (Pontiac for example) because the plug is in such a bad location that when the intake valve opens cold fuel is blown right across the plug making it appear rich.

Reading plugs is tricky. Most guys don't have nearly enough ignition. I'm leaning that way with the OP.

 

[Dicer]

Here's a pic that will help you read your plugs, it will show you by looking at different locations for problems areas....

 

[my5thmopar]

Looks like drool tube slant six. Agreed, plug too hot or too much timing. Use a NGK ZFR5N anyway.