Fouled Spark Plugs? 1979

[Pescado]

So while looking around at the engine and planning a carb plus intake mani upgrade I noticed my water pump leaking….Now I was planning a timing belt replacement this spring and already ordered the parts which included a new water pump so I have everything I need to replace it so that’s a bonus. While planning to do the timing belt and pump i pulled out two plugs just to have a look as I’ve read that I’ll need to check the engine for top dead center while working on the timing belt install. The plugs that came out do not look great to me….keep in mind I’m a newbie this is the first car I have really done any work on so lots to learn for sure but I’m really enjoying it and working along side my son has been great. Did some research based on how the plugs look and I feel like these would be classed as “fouled” …car running too rich? Honestly the car runs great and idles nice, there is some oil leaking from the valve covers on to the plugs…could this be the cause of the dirty plugs?

[18Fiatsandcounting]

The plugs that came out do not look great to me….]

They don't look shiny, so it's probably not oil fouling. It looks like it's running rich as you noted, and here are some possible causes:

1. Wrong spark plugs. Champion RN9Y or the equivalent is what's specified.
2. Choke is not disengaging completely.
3. Car driven only on very short trips.
4. Thermostat not working so the engine is very slow to fully warm up.
5. Various carburetor issues including leaks in the hoses.

Do any of those seem like they might apply? By the way, go ahead and pull all 4 plugs and see if they all look fouled. If only two are fouled, it could be another issue.

-Bryan

[Nut124]

Running too rich. Then again, rich usually runs OK, like you are saying, at the expense of fuel economy and some power.

Regarding your timing belt job. Carefully mark the crank and cam pulleys before taking the belt off so you can get it back in the same position. No need to find TDC as long as you can get it back the same it is now, since it runs good.

TDC mark is needed for ignition timing though.

[Pescado]

Thanks Nut124 good to know.

Honestly I think I may hold off the timing belt for a while...seeing as I'm changing plugs, waterpump, drive belt, and have been in up to my elbows bumping things around I'd like to see how the car starts after its hibernation before doing too many changes...just in case things aren't good there will be less to trouble shoot if I'm not questioning my timing belt replacement. I know this means putting parts back on and than taking them off again to do the timing belt but I'll chalk it up as practice.

[Pescado]

Here’s a picture of all 4 spark plugs…2 and 3 definitely look better. What’s the deal?

[Pescado]

The plugs that came out do not look great to me….]

They don't look shiny, so it's probably not oil fouling. It looks like it's running rich as you noted, and here are some possible causes:

1. Wrong spark plugs. Champion RN9Y or the equivalent is what's specified.
2. Choke is not disengaging completely.
3. Car driven only on very short trips.
4. Thermostat not working so the engine is very slow to fully warm up.
5. Various carburetor issues including leaks in the hoses.

Do any of those seem like they might apply? By the way, go ahead and pull all 4 plugs and see if they all look fouled. If only two are fouled, it could be another issue.

-Bryan

1. Very possible I will be replacing with the attached picture
2. How can I check this?
3. Some but not many…I try and make the trips no less than 20min as I have heard about this
4. How can I check this?
5. Most likely but this will be replaced soon

Thanks for the help

[Pescado]

[kilrwail]

Don't use those NGK racing plugs. They are too cold and the engine will barely run. As Bryan suggested, use Champion RN9Y or NGK BPR6ES.

[18Fiatsandcounting]

As suggested by Kilrwail and Nut124, it looks like it might just be a matter of the wrong plugs. For posterity, here are the answers to your questions below.

1. Change out the plugs and see what that gets you.
2. Take off the air filter cover and you should see one, possibly two butterfly valves in the top throats of the carburetor. With the engine cold, they should be closed (or nearly so). When the engine starts, they should open slightly, and as the engine warms up, they should open fully.
3. Sounds like short trips are not the problem.
4. Observe your temperature gauge. Unless you are in a super cold climate, the engine should reach normal operating temperature (about halfway on the gauge) in 10 or 15 minutes (5 to 10 minutes in the Summer). If the gauge shows "cold" for much longer than this, your thermostat could be stuck open. Or you're just in a really cold climate.
5. See answer #1 above.

-Bryan

1. Very possible I will be replacing with the attached picture
2. How can I check this?
3. Some but not many…I try and make the trips no less than 20min as I have heard about this
4. How can I check this?
5. Most likely but this will be replaced soon

[Pescado]

Ok thanks guys…the plugs in the picture are champion 3415.

[Nut124]

Ok thanks guys…the plugs in the picture are champion 3415.

According to google, that Champion plug correlates to NGK heat range of 5. The recommendation for normal use is NGK 6. The champion plug is hotter than NGK 6 so any fouling is unlikely to be because of the plug. 2 & 3 look pretty normal for a carb engine.

Single carb/manifolds do not always distribute even mixture to all cylinders.

The NGK race plugs are NGK heat range 9. Pretty much full race only.

[18Fiatsandcounting]

I'm kinda getting the impression that the "Italian Tune-Up" is what you need. Drive the engine hard, 4000 to 6000 rpm at full throttle for a while, and I'll bet your spark plugs will look perfectly normal. These engines love that.

-Bryan

[18Fiatsandcounting]

Drive the engine hard, 4000 to 6000 rpm at full throttle for a while, and I'll bet your spark plugs will look perfectly normal.

Just remembered that this is a 2L engine, so perhaps 4000 to 5000 rpm is a better idea.
No point in stressing what might be a tired engine.

[Pescado]

Ok thanks guys…the plugs in the picture are champion 3415.

According to google, that Champion plug correlates to NGK heat range of 5. The recommendation for normal use is NGK 6. The champion plug is hotter than NGK 6 so any fouling is unlikely to be because of the plug. 2 & 3 look pretty normal for a carb engine.

Single carb/manifolds do not always distribute even mixture to all cylinders.

The NGK race plugs are NGK heat range 9. Pretty much full race only.

Ya I rushed into buying those plugs…thought I would be ok seeing as they came from a Fiat speciality shop, still my bad. The intake manifold on my 79 is still the original double…Guess I’ll be buying some new plugs thanks for the info.

[Pescado]

Drive the engine hard, 4000 to 6000 rpm at full throttle for a while, and I'll bet your spark plugs will look perfectly normal.

Just remembered that this is a 2L engine, so perhaps 4000 to 5000 rpm is a better idea.
No point in stressing what might be a tired engine.

Well Bryan this sounds like it will be the most exciting of any repairs I’ve done yet…lol.

Can you expand on “tired engine” for me