What would cause fouling on just half of the spark plug?

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BMac Attack

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Ok, I spent the evening putting everything back together. I did the vacuum test to check for a leaking intake gasket by plugging the valve cover holes and the PCV valve and plugged in a vacuum gage to the dip stick. The results were 4.5 inches of Hg vacuum at idle on a cold motor. I’m sure when it warms up or driven down the road it gets worse. My understanding is that I’m supposed to have some positive pressure when everything is plugged like that. I’m thinking I need to the remove the intake, check that sucker for flatness and replace the gasket. It’s an Edelbrock gasket, and Im going to get a Fel-Pro one to replace it. I feel hopeful about that fact that I have a good idea of what my problem is and also frustrated that I didn’t get it right when I put the motor in. I’m so looking forward to a reliable running rig that I can just drive.
 

SirRobyn0

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Ok, I spent the evening putting everything back together. I did the vacuum test to check for a leaking intake gasket by plugging the valve cover holes and the PCV valve and plugged in a vacuum gage to the dip stick. The results were 4.5 inches of Hg vacuum at idle on a cold motor. I’m sure when it warms up or driven down the road it gets worse. My understanding is that I’m supposed to have some positive pressure when everything is plugged like that. I’m thinking I need to the remove the intake, check that sucker for flatness and replace the gasket. It’s an Edelbrock gasket, and Im going to get a Fel-Pro one to replace it. I feel hopeful about that fact that I have a good idea of what my problem is and also frustrated that I didn’t get it right when I put the motor in. I’m so looking forward to a reliable running rig that I can just drive.
Yup that's a leaking intake gasket. I used the thick blue Fel-pro gasket.

When you pull the intake the trail of oil from the gasket into the effected cylinders will be obvious.
 

BMac Attack

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By the way, here is a pic of my truck in its current configuration. I’ve done a bunch to it over the last couple of years, I’m a tall guy but engine work on a truck with a 6 inch lift and 37s is not easy!
 

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BMac Attack

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Yup that's a leaking intake gasket. I used the thick blue Fel-pro gasket.

When you pull the intake the trail of oil from the gasket into the effected cylinders will be obvious.
That’s exactly what I’m going to go with. Do you have any suggestions on RTV usage, the little China Wall rubber pieces and such?
 

Ricko1966

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I don't have a pic of mine handy but will try to find a pic so you'll know what I'm talking about. Slip over the tire and working under the hood is much easier.
 

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BMac Attack

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I don't have a pic of mine handy but will try to find a pic so you'll know what I'm talking about. Slip over the tire and working under the hood is much easier.
Very cool, that probably won’t fit a 12.50x37 but I’m sure I could make one.
 

Ricko1966

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I'll bet they make them that big,but I'd just make one.
 

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SirRobyn0

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By the way, here is a pic of my truck in its current configuration. I’ve done a bunch to it over the last couple of years, I’m a tall guy but engine work on a truck with a 6 inch lift and 37s is not easy!
I like to sit on the core support with one foot on each side of the engine, as much as possible for jobs like that, though my stomach gets in the way.

That’s exactly what I’m going to go with. Do you have any suggestions on RTV usage, the little China Wall rubber pieces and such?
Rubber pieces HA! Old mechanics trick. Toss those things. Lay a nice tall bead of silicone RTV down. Got to use the good quality stuff. I like to use right stuff gray, but the black is fine for that application, some guys prefer Permatex gray or black. You have to have clean surfaces on both sides I like to use lacquer thinner and a rag because it cleans like crazy, dries fast and leaves no residue. That's kind of old school but it's what I like to use, I'm sure brake cleaner and rag would do fine. The reason for getting rid of the rubber pieces is they are known to leak over time and are generally a pain to get in place. But if you go just straight silicone RTV you have to make sure you lay enough and even enough to form the seal, and not smear it during manifold install.

If your running an EGR valve (which you should be) when the intake is off is a good time to make sure the manifold passages are clear.
 

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Very cool, that probably won’t fit a 12.50x37 but I’m sure I could make one.

A topside creeper is also very handy although a 4’ step ladder wired to the front bumper and an old seat cushion or a stack of towels works as well.
Trouble is most of the topside creepers don’t go tall enough. I got one a couple years ago and modified it to work on taller trucks. It’s not too sketchy…
 

scrap--metal

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Do you have any suggestions on RTV usage, the little China Wall rubber pieces and such?
Don't use those little rubber things. Like @SirRobyn0 said, throw them away. Follow his directions using "The Right Stuff" on the china wall and around the coolant passages on the ends.
 

SirRobyn0

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Don't use those little rubber things. Like @SirRobyn0 said, throw them away. Follow his directions using "The Right Stuff" on the china wall and around the coolant passages on the ends.
Another point of interest, if there is pitted on the heads or intake manifold around the ports, (which is much more common on aluminum intakes, not our castiron ones), but if there is pitting those pits can be filled in with epoxy and sanded smooth. And by epoxy I mean JB weld.
 

SirRobyn0

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A topside creeper is also very handy although a 4’ step ladder wired to the front bumper and an old seat cushion or a stack of towels works as well.
Trouble is most of the topside creepers don’t go tall enough. I got one a couple years ago and modified it to work on taller trucks. It’s not too sketchy…
We use to have one of those at the shop, but some how or another it disappeared about 4 years ago. IDK how something that big grows legs but it did.

I did really like that thing but could not be on it for a long time, I think a big part of that is just the pressure it puts on my belly, makes it harder to breathe, for me.
 

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Looks like rings on odd No. cly at least
 

BMac Attack

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I was finally able to get the top of the motor removed. Here are some pics. I noticed a couple of places where the vacuum leak could be coming from: - intake bolts above cylinder 1 didn’t have washers and show some rust marks, the distributor gasket had a break in it, the intake gasket had a spot where it was broken. As you see the photos, does anything else look messed up?
 

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Last edited:

BMac Attack

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I was finally able to get the top of the motor removed. Here are some pics. I noticed a couple of places where the vacuum leak could be coming from: - head bolts above cylinder 1 didn’t have washers and show some rust marks, the distributor gasket had a break in it, the head gasket had a spot where it was broken. As you see the photos, does anything else look messed up?
 

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