Opinions on this spark plug issue please...

[89Suburban]

Remember I put brand new heads on my TBI 350. These plugs are almost a year old. The mechanic that installed them told me that they are a heat range cooler than what is supposed to be on the motor. I ran them for the past 10 months and had a miss develop and traced it to these as you see, the #3 cylinder spark plug was built up with crap and wasn't firing.

I was assuming it was due to the cooler heat range and the plug was not hot enough to keep the crap blown off of it. I have heard many other opinions such as timing and a lean mixture causing this. I would like to hear more opinions on this and what direction I should go. For the mean time I installed the correct heat range plug and it's running fine. However I would like to fine tune the timing.

I have not had a chance yet but I am planning on pulling the #1 to find the true TDC. I believe my timing tab is bent and not showing an accurate reading under the timing light. So using the 'ol screwdriver through the spark plug hole method I am hoping to nail down exact TDC and time the engine from there.

I have no idea where to begin with trying to figure out if I am having a lean mixture issue. I am being told that the plugs should show a brown color and they are mostly white.

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[89Suburban]

Jims86 also suggested I use a timing light to inspect the injector spray. Here are two vids. I am not sure what I am supposed to be looking for.....


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[smurph20]

Injector looks to be doing good i think you just had to cold of a plug

 

[Jims86]

That looks pretty good injector wise, you are looking for that nice cone pattern, with no drops, just a fine spray.
Just for the heck of it, See if you can find some 3M fuel system cleaner, and dump it in your tank when your fuel gets down to a little above a 1/4 tank. As far as timing marks, is your timing indicator bolted to the timing cover, or welded?

 

[89Suburban]

That looks pretty good injector wise, you are looking for that nice cone pattern, with no drops, just a fine spray.
Just for the heck of it, See if you can find some 3M fuel system cleaner, and dump it in your tank when your fuel gets down to a little above a 1/4 tank. As far as timing marks, is your timing indicator bolted to the timing cover, or welded?

It's welded, but it looks crooked to me.

 

[dhamp]

Man, I'd leave the correct plugs in it, ride it for a month or two, then recheck them to see if that's all you need to do unless you are fairly sure your timing is off.

 

[Jims86]

John, I know its a tough squeez, but can you get a decent pic of the timing mark?
If it doesnt ping, I wouldnt worry too much... especially since the system has a knock sensor.

 

[smurph20]

Man, I'd leave the correct plugs in it, ride it for a month or two, then recheck them to see if that's all you need to do unless you are fairly sure your timing is off.

He said in a n earlier post the mechanic that replaced the heads ran a colder plug then stock he put the correct ones in it.

 

[dhamp]

He said in a n earlier post the mechanic that replaced the heads ran a colder plug then stock he put the correct ones in it.

Right. That's what I'm saying. If it had the wrong plugs in it, and it's running fine now that it's got the right range of plug in it, I would just keep it pushin' unless it goes some months and gums the plugs again. If it's running good and the fuel is spraying right, I would assume the problem is fixed now that he's got the right plugs in it.

 

[Jims86]

Right. That's what I'm saying. If it had the wrong plugs in it, and it's running fine now that it's got the right range of plug in it, I would just keep it pushin' unless it goes some months and gums the plugs again. If it's running good and the fuel is spraying right, I would assume the problem is fixed now that he's got the right plugs in it.

I am thinking that his mechanic put those in, because the replacement heads didnt have the original swirl port ramps in the intake runners, and the new heads are more like L98 iron Camaro heads. The only heads you really need to worry about running "head specific" plugs, are vortecs.

 

[89Suburban]

John, I know its a tough squeez, but can you get a decent pic of the timing mark?
If it doesnt ping, I wouldnt worry too much... especially since the system has a knock sensor.

I get a rare ping, and it depends on weather conditions, and it only happens when I drop the hammer in 3rd gear heading up the highway with the boat on the back and in dry conditions. If it is humid it is fine. You can hear the knock sensor kick in right away whenever it does pop up. I would say once a week or so.

Here is pics I dug out of the head gasket thread. See how the tab looks crooked?

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[89Suburban]

I am thinking that his mechanic put those in, because the replacement heads didnt have the original swirl port ramps in the intake runners, and the new heads are more like L98 iron Camaro heads. The only heads you really need to worry about running "head specific" plugs, are vortecs.

So what is that build up from then? It is not burning oil, well, the exhaust is not smoking blue anyway.

 

[Jims86]

Well, if that is carbon build up, it would be too cold of a plug. But, CR43TS is listed as stock replacement for your truck. Now that I see your timing scale....sheesh, that thing is ******! If you can get some needle nose pliers down there, and straighten it out, using the timing egroove as a straight edge(set the groove at one of the far ends of the scale) you may be able to correct it.
For now, it looks 3 or 4 degrees retarded.....I would say for now, to set it a little above 2 degrees the way the scale is bent.

 

[89Suburban]

Well, if that is carbon build up, it would be too cold of a plug. But, CR43TS is listed as stock replacement for your truck. Now that I see your timing scale....sheesh, that thing is ******! If you can get some needle nose pliers down there, and straighten it out, using the timing egroove as a straight edge(set the groove at one of the far ends of the scale) you may be able to correct it.
For now, it looks 3 or 4 degrees retarded.....I would say for now, to set it a little above 2 degrees the way the scale is bent.

Phuk, I didn;t check the numbers on the plugs, I was just going by what he told me. Anyway, I am going to use the screwdriver trick and see where the mark is on the scale at absolute TDC. Do you think the timing being off will cause that carbon buildup?

 

[Jims86]

Phuk, I didn;t check the numbers on the plugs, I was just going by what he told me. Anyway, I am going to use the screwdriver trick and see where the mark is on the scale at absolute TDC. Do you think the timing being off will cause that carbon buildup?

It could very well be part of it, you may also see a small increase in power and economy once we get this figured out.