Spark plug rich or lean?

[Gungho]

Jeep’s been running pretty good lately. However, the exhaust still has a pretty strong smell. I pulled one of the spark plugs to see if I was running rich. Does it look like it’s running rich or is this how it should look? It also had some oil on it that I’m not sure of if it’s normal.

 

[JeffP]

Jeep’s been running pretty good lately. However, the exhaust still has a pretty strong smell. I pulled one of the spark plugs to see if I was running rich. Does it look like it’s running rich or is this how it should look? It also had some oil on it that I’m not sure of if it’s normal.

You have several problems.
1. Put in a clean air filter!
2. Run Premium gas!
3. It’s likely too late but you have been using the wrong oil!
4. Looks like the carb is adjusted correctly but excess voltage on the secondary side of your ignition. What coil are you using? Heat range of the plugs?

 

[Gungho]

1) My air filter is pretty much brand new. What makes you say replace it?
2) Do you recommend always use premium?
3) I’ve been using 10w-30 oil. When I searched, this seemed the most common recommendation. What do you recommend?
4) I put in an HEI distributor and can’t remember heat range of plugs.

I’m new to cj’s and learning as I go, so any reasons for recommendations would be great to help me learn.

 

[JeffP]

1) My air filter is pretty much brand new. What makes you say replace it?
2) Do you recommend always use premium?
3) I’ve been using 10w-30 oil. When I searched, this seemed the most common recommendation. What do you recommend?
4) I put in an HEI distributor and can’t remember heat range of plugs.

I’m new to cj’s and learning as I go, so any reasons for recommendations would be great to help me learn.

Air filter because of debris / deposits on plugs.
Always use premium! Gasoline has changed drastically since your Jeep was made. Octane ratings are MUCH lower. What was once considered “regular” had a higher octane rating than premium does now. Save your engine... run premium!
The weight of the oil doesn’t matter nearly as much as the additives that are in it... or not in it! I just wrote a post about it, you really should read it.
Another thing about gas. It can’t sit anymore! Todays gas degrades really fast with a maximum life of three months! If you don’t drive it enough at least add some stabilizer.

 

[Gungho]

Thanks for the response. The gas thing makes sense.

 

[Lumpy Grits]

Don't look bad-
What make and P/N plugs are these? How many miles on'em?
What is the gap set to?

Make sure BOTH idle air mix screws are turned out the EXACT same amount.
Use a vacuum gauge, to help you set the idle mix.

What oil are you runing? How many miles on the engine?
When was the last time you cleaned/changed the PCV valve.

Who's air filter do you run? Hope it ain't a K&N.
LG

 

[Gungho]

I can’t remember make of the plugs. I think I gapped them to .040 (replaced them over a year ago).

I’m using Castrol high mileage oil.

I’ve never changed pcv valve. Didn’t know I needed too.

Odometer says 59,000, but I’m sure it’s probably 159,000 miles.

Air filter is just a generic stock one. Any suggestions on replacements?

 

[Lumpy Grits]

Stay with a good paper A/F.
The plug brand and heat range are on the side of the plugs. Very important to know. .040 gap, is a bit wide for OEM ign.
What weight oil are you using in the engine?
You really need to keep a log book showing what work was done, with date/mileage and all P/N's of items used.
YES-PCV valve need to be cleaned/changed from time to time.
What do you have for a service/maintenance manual?
LG

 

[Gungho]

I do have a HEI distributor, which I read needs a wider gap. I’m using 10w-30 oil.

I started a log when I first got the Jeep, but got bad about keeping it updated.

I have the Haynes manual and read the fsm online when I need it.

 

[RiverandSand]

I do have a HEI distributor, which I read needs a wider gap. I’m using 10w-30 oil.

I started a log when I first got the Jeep, but got bad about keeping it updated.

I have the Haynes manual and read the fsm online when I need it.

The plug looks OK to me, you want a tanish color. What you don't want to see is black sooty plug (rich) or oily plug (oil burning). As for deposits that can come from gas used, filters not filtering properly or pcv sucking up small amounts of oil instead of just air, I wouldn't be to alarmed by that, just check filters and pcv valve. HEI is usually a hotter spark than a stock jeep, the gap of 040 to 045 is normal. That plug is fairly hot (extended tip) for HEI which typically runs a little colder plug (tip closer to base).

 

[Gungho]

What type of spark plug do you recommend?

 

[Lumpy Grits]

Standard Autolite 985.
LG