One more data point. I changed the oil a month ago. As of today, it’s pretty nasty. That’s less than 300 miles… I think I’ll do another oil change and filter change. See pic for ref.



Pretty dirty for 300 miles since last change.

 

Looks like the same way rich condition from never getting warmed up all the way
That should all burn off the plugs nicely once the engine is at operating and taken for a longer drive

 

Years ago, I was working at a dealership and was handed a repair order for a mid-90's Astro Van that was a no-start. Turns out it was a no-crank. Hit the key - heavy "thunk".

Checked the oil and there was nothing on the dipstick. While checking things over, a few things caught my eye. It was a pretty low-mileage vehicle for the year and in impeccable aesthetic condition. However, the oil change sticker in the window was 4 years old and the vehicle only had <400 miles since the change was done. Also, the tailpipe was restricted to about 1/3 of its original size and plugged with carbon.

It turns out that the owner drove the vehicle one block to work every day and back home every evening. There was nothing in the oil pan, the engine was seized, and it was the dirtiest, most sludged-up engine I had ever taken apart. It's a miracle it even ran until it died - every piston ring was stuck from carbon buildup. It couldn't have had any compression.

Math says this engine burned off 4.5 quarts of oil in less than 400 miles.

Engines NEED to get up to operating temperature for a while and fairly often when they are driven. Oh, and if a person lives ONE BLOCK from their place of employment and still DRIVES that distance while being fully able to walk....well, that's lazy and sad.

 

I have to take my pickups on longer drives every so often. I prefer to go to the mountains so I can get some heat into the engine. I drive 15 minutes each way to work, and the other trips are shorter, since I live about a mile from my small downtown.

If I neglect to take the longer trips I get condensation in the valve covers, which soon turns to a milky creme froth, seen on the bottom of the oil fill cap and inside the valve cover. Truck gets a little sluggish, and oil starts getting dark too soon with nothing but short trips.

I thought I was doing enough longer trips on both pickups until I looked in the valve cover of the V-10 Dodge, and thought I had a cracked head or blown head gasket. The Ford looked almost the same way.

I drove both on long mountain trips to get as much crud burnt out before changing the oil. I switched to diesel around 18 years ago. I also switched to synthetic blend diesel oil that change also. I now rotate driving each truck for a week or so, and take each on extended drives as much as possible. I took the Ford on a two-plus hour drive around here in the rolling hills a week ago today. The Dodge is due a trip, most likely this week.

Since then I have had no more buildup of foam/milkshake, and the inside of the engines look great. Pulled #1 plug in the Ford last week to check it. I don't know how many years oid it is, but at least 8+ years old, still looks new with no oil or carbon buildup.

I took this picture of inside the valve cover of my Ford 4.9 engine last week. 1987, original engine, never been in to. What might appear to be any sludge is just the casting of the rocker and the reflection of the flash. I took this picture after dark.

 

From reading your post and the condition of the oil after 300 miles. Your problem started with the carb and I think it is still a carb problem. It looks like to me like you have fuel wash down.

 

Folks - Circling back to the fouled plugs and miss issue. I’ve been taking the truck out for longer drives for extended periods at temp. On return, I’m noticing a fuel smell from the air filter. Wondering if there is a heat soak issue. I’m running a stock 2150. Anyone using a spacer to prevent fuel boil? Thoughts?

 

From your pictures, it appears you have the factory EGR plate under the carb. It wouldn't be a bad idea to get longer studs and put a spacer between it and the carb to keep the heat away. Today's fuel boils at much lower temperature than 1970"s fuel.

Have you checked your timing with the vacuum hose to the distributor off and plugged? Your vacuum seems a little low, and low timing could cause that and more heat buildup in the engine.

Very nice looking engine you have.

 

Weather nice so pulled all plugs to check on possible improvement since taking longer drives. See below pic. Not bad! However, the miss is still there - if not worse.

Timing next of my list. Maybe a spacer. Also thinking of new plug wires. I exhausted SSD 107.

 

Huge difference in condition of spark plug. What kind of idle miss do you have, engine running rough and stumbling, or a steady, solid miss, on one or more cylinders?

 

Irregular. Only noticeable at idle.I’ll send a video if you like. I plan to pull each plug while running to see if I can isolate it (not make it worse). May swap plugs…again. Throw a sink at it. You know. The usual.

 

Possible lean misfire?
Have you tried adjusting the carb mixture screws to fatten it up?
Your timing is correct right?

 

A video long enough to hear what it's doing would help a lot.

 

@manicmechanic007 I have my suspicions on timing: no timing marks. But it’s close. Timing on the short list. Mixture screws: I try to run a bit lean but will see if a half turn rich does anything. Not holding breath.

@yardbird ill put a video link up tomorrow. You will see it more than hear it on video , perhaps. A good miss jostles the hood.

My thoughts on approach:

1. Swap plugs. If miss resolved, rules out electrical (wires, cap, etc). Also points me to look for cause (heat soak?)

2. If miss not resolved with new plugs:

3. Mixture. Can’t hurt.

4. Timing. Validate tdc, recalc 12 degrees, and set accordingly.

5. Spark plug wires?

6. Rotor and cap?

Video tomorrow.

 

I see you still have all of the emission equipment on your engine. Have you checked all that stuff to see if it is working correctly? If you don't have a shop manual, it's time to buy one. Because if all that stuff isn't working as designed, you are going to have all sorts of problems.
Also your spark plug looks like you have way to much total timing. The color change on the ground strap should be close to where it makes a 90 degree turn.
This is a picture of a plug from my engine this is about as far as you would want that color change to be without risking preignition.
This is an Autolite 24

 

Link to video :

@Crop Duster great feedback. Timing has been problematic since distributor was stuck (would not turn) and took some major elbow grease to unfreeze.

The video is intended to show the subtle miss. Not huge but definitely there. The hood shimmies a little bit as it periodically misses. Hope this helps. You guys are great - thx.