How do you clean your slant six plugs, or do you even clean them at all?

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cruiser

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Hi Guys: I run NGK ZFR-5N plugs in the totally stock 225 six in my 74 Duster. Rebuilt Holley 1945 runs well, air/fuel mixture and idle set to factory specs, timing at 10 degrees before. The engine has 95K miles on it. The plugs seem to foul a bit after about 11000 miles, so I just bought a pneumatic spark plug cleaner from Harbor Freight. It didn't work very well, even when used as directed. Why would a healthy engine foul the plugs this soon? The accompanying photo shows the plugs after 11K miles, with the #1 plug at the top and #6 at the bottom. How do they look to you? Is it easier to just put new plugs in? That's kinda pricey. What do you do to get your plugs squeaky clean before you reinstall them? How long would you normally expect a set of good plugs to last in a slant? Is 11000 miles about when you clean or replace yours? Thanks.

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I use a wire brush and just clean all the crud off them and put them back in. If they are real bad I've been known to scrape the junk off as well, but at that point it's probably a good idea to just replace them.
 
Whats wrong with those? Top looks a little black but it could be a ring issue. Maybe a hotter plug next time? NGK are lower number is a hotter plug.
 
Whats wrong with those? Top looks a little black but it could be a ring issue. Maybe a hotter plug next time? NGK are lower number is a hotter plug.
I'm not sure why the #1 plug is fouled like that. When I installed a set of new identical plugs, the car immediately idled a lot better.
 
Five of your plugs don't look fouled to me—not at all. They look fantastic; they speak of damn-near-perfect fuel mixture and excellent oil control. The uppermost plug is slightly dirtier, but still has trouble meeting any real definition of "fouled". There's no crusty, gummy, or flaky buildup, and nothing bridging the gap.

If the engine idled a lot better with new plugs, I'd say leave 'em in awhile and see how it goes. You should be able to get at least 20k miles out of a set of good-quality plugs—one of the advantages of today's much cleaner gasoline versus the dirty gunk that was available when these cars were new.

Also quit buying "tools" from Harbor Freight—it's easier and more efficient to just set a pile of cash on the street and light it on fire.

Also, back in the "good old days" when service stations had sandblaster-type spark plug cleaners, a whole hell of a lot of sand stayed in the crevices of the spark plug, and got released directly into the engine after the plugs were reinstalled.
 
Five of your plugs don't look fouled to me—not at all. They look fantastic; they speak of damn-near-perfect fuel mixture and excellent oil control. The uppermost plug is slightly dirtier, but still has trouble meeting any real definition of "fouled". There's no crusty, gummy, or flaky buildup, and nothing bridging the gap.

If the engine idled a lot better with new plugs, I'd say leave 'em in awhile and see how it goes. You should be able to get at least 20k miles out of a set of good-quality plugs—one of the advantages of today's much cleaner gasoline versus the dirty gunk that was available when these cars were new.

Also quit buying "tools" from Harbor Freight—it's easier and more efficient to just set a pile of cash on the street and light it on fire.

Also, back in the "good old days" when service stations had sandblaster-type spark plug cleaners, a whole hell of a lot of sand stayed in the crevices of the spark plug, and got released directly into the engine after the plugs were reinstalled.
Thanks, Dan. Last time I tuned the motor, I set the idle speed by guessing since I didn't have a tachometer. I then set the idle mixture by "feel", trying to get the smoothest idle with the vacuum advance line removed and plugged as the shop manual recommends. That, along with the new NGK plugs, really made her run well. Later on, I finally got an old school dial type tachometer and checked the idle speed that I set previously. It was at 725 RPM. The shop manual recommends 750, so I'm a good guesser I suppose. As for cleaning the plugs, yeah I scrupulously clean out even the tiniest bit of grit from the inner electrode after I clean them. I'm certain that not a single bit of blasting material or anything else gets introduced into my cylinders. I use a really sharp narrow tipped X-Acto knife to do this. Finally, your point about Harbor Freight is well taken. I returned the plug cleaner and the abrasive that I bought there the next day.
 
Hi Guys: I run NGK ZFR-5N plugs in the totally stock 225 six in my 74 Duster. Rebuilt Holley 1945 runs well, air/fuel mixture and idle set to factory specs, timing at 10 degrees before. The engine has 95K miles on it. The plugs seem to foul a bit after about 11000 miles, so I just bought a pneumatic spark plug cleaner from Harbor Freight. It didn't work very well, even when used as directed. Why would a healthy engine foul the plugs this soon? The accompanying photo shows the plugs after 11K miles, with the #1 plug at the top and #6 at the bottom. How do they look to you? Is it easier to just put new plugs in? That's kinda pricey. What do you do to get your plugs squeaky clean before you reinstall them? How long would you normally expect a set of good plugs to last in a slant? Is 11000 miles about when you clean or replace yours? Thanks.

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You might also want to do a compression test on your #1 and another cylinder to compare the two. If the compression on #1 is low, put about a tablespoon of oil into the plug hole and run another test. If the pressure improves, then the oil is temporarily sealing the rings. Fresh plugs require less spark to fire, so if the compression on #1 is close to the same as the others, then you may have a flaky plug wire on #1.
 
You might also want to do a compression test on your #1 and another cylinder to compare the two. If the compression on #1 is low, put about a tablespoon of oil into the plug hole and run another test. If the pressure improves, then the oil is temporarily sealing the rings. Fresh plugs require less spark to fire, so if the compression on #1 is close to the same as the others, then you may have a flaky plug wire on #1.
Okay, will do. The plug wires are brand new, BTW, so I'm kinda ruling them out. Thanks - cruiser
 
When son was running jet skis a lot years back, we had a little spark plug sand blaster. Worked great. Sandblasted them and then blew them out with compressed air. I forget what the medium was, but it wasn’t sand.
 
When son was running jet skis a lot years back, we had a little spark plug sand blaster. Worked great. Sandblasted them and then blew them out with compressed air. I forget what the medium was, but it wasn’t sand.
The real issue with those was people would not blow the media out of the plug when finished. JC Whitney used to sell those as I recall.
 
Was the #1 plug dark like that before changing the wires? Did you change the distributor cap & rotor as well?
I'm not sure what the #1 plug looked like prior to changing the wires, because I didn't check it. But yes, I did replace the cap and rotor.
 
I'm not sure what the #1 plug looked like prior to changing the wires, because I didn't check it. But yes, I did replace the cap and rotor.
If your compression test comes back good on #1, then I would swap plug wires between #1 and #2 (assuming length is good) to see if the problem moves to #2. Just to rule out a bad plug wire. Ya never know!
 
Unless I'm tuning, if used plugs are coming out, new plugs are going in
 
The real issue with those was people would not blow the media out of the plug when finished. JC Whitney used to sell those as I recall.

Yep, ours was probably jc Whitney. As often as those stand up jet skis fouled plugs, we would have gone broke buying new plugs.
 
Plugs the correct heat range and an engine in proper tune, the plugs will keep themselves clean.
 
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