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Oemtech · 12-30-2008, 04:43 PM

I had a customer stop by the shop for a set of Taylor Wires and some AC/Delco plugs. Needless to say I was a bit surprised when he informed he that the plugs/wires were originals and had 78,000 miles on them.

We lost 4 of wires during removal. 3 of wires broke at the spark plug connector (pretty much normal) and 1 actually separated inside the metal boot cover.

But, the real surprise were the original DENSO spark plugs. I have long said that 100,000 miles is doable but I do not recommend it. Why.... because the OEM's quote numbers under ideal conditions. Motorhomes, by their nature, do not fall into the "ideal cognitions".

78,000 Mile Plugs

Old & New Side by Side

On Edit - correct some grammar

Fred and Bonnie · 12-30-2008, 05:59 PM

Sure burns clean and hot!

Fred

Max Hubrich · 12-31-2008, 04:26 AM

Story time, For what its worth---

In '98 I flew the NASCAR, Robert Yates race team crews (#88 & #28 cars), around for the entire season-- January thru November. I was in the garage area watching and observing after practice lap runs --- many times. As soon as the cars came in, a crew member immediately pulled all the plugs - Every time!! Doug Yates (Robert Yates son) looked at each plug with a high powered, lighted, magnifying glass. After watching so many times I finally asked Doug, kidding -- What in the world are you looking at all the time? He said it's the only way we know what's going on inside the engine! True!!

Doug would have a fit if he saw these plugs!! Efficiency had to be a big zero!

I was there as a "gopher" running out getting the crews lunch most of the time. They gave me $200, and I brought back hamburgers, milk shakes, barbecue, chicken, etc. The drivers, Dale Jarrett and Kenny Irwin always required a special stop at the super market for their "pasta salads" meals. Kenny was killed in New Hampshire two years later. Dale Jarrett finished second in the championship in '98. He won the championship the next year, in '99.

Rock-Rocker · 12-31-2008, 06:23 AM

Do you think there is a chance he'll get better fuel economy now?

Oemtech · 12-31-2008, 07:03 AM

Fred

Clean and hot... I don't think so. I suspect this is oil deposits from GM's (1 qt to 100 gallons of fuel) oil usage solution.

Rock-Rocker,

Will he see better mileage? I can't image that he won't see some improvement.

I did talk to him after he had a chance to drive back to the camp ground, just a short drive of about 30 miles. His initial reaction was as others have said... It seems to run quieter, idles better etc. It is amazing how well the "Butt dyno" works.

Oemtech · 12-31-2008, 07:49 AM

I didn't post this photo with the others just to see what folks thought. But, here is the other side of the 4 plugs in the first photo.

Both sides should look like this. Also, checked the gap and they were .062 to .065. Lastly, the platinum tips are almost gone.

Finhawk · 12-31-2008, 09:37 AM

Ok, so why the difference in the sides? Is that a GM thing??

rogueii · 12-31-2008, 09:39 AM

When I had the Ultrapower done, I ordered new plugs and the new Plug cables. I cleaned the original plugs and re-gapped them to 0.045. My plan is to changed the plugs about every 12k to 15K. Check and clean and/or replace as needed.

Fred and Bonnie · 12-31-2008, 09:53 AM

Quote:

Originally posted by oemtech:
Fred

Clean and hot... I don't think so. I suspect this is oil deposits from GM's (1 qt to 100 gallons of fuel) oil usage solution.

Dale, I would say 1qt in 700 miles is way above acceptable oil consumption.

Fred

Oemtech · 12-31-2008, 11:44 AM

It's called flame travel. Due to the fact that the 8.1L head design is not a "Hemi" style head the combustion flame travels at an angle so you have the conditions you see on the plugs. Now if you what you can "index" the plugs so minimize this condition.

Full-Timers · 01-01-2009, 05:02 PM

Interesting. It looks like the plugs WERE indexed since the “Flame Travel” was in the same direction on all 4 plugs. Odd.

DriVer · 01-01-2009, 05:39 PM

Quote:

Originally posted by rogueii:
My plan is to changed the plugs about every 12k to 15K. Check and clean and/or replace as needed.

I don't think that you will have to replace the plugs with double that mileage and you will want to avoid cleaning these types of plugs with abrasive compressed air type spark plug blasters.

I am not so inclined to clean the plugs given the task of removing them, I might just replace them but I believe I would wait for about 30K if you are really aggressive. May as well gap new ones and throw them in.

Now that said Max Hubrich said the The Yates engine guys pulled the plugs after each run with the engine and put them under a microscope. This is exactly what you need to do when you have that type of engine program.

On our motorhomes, I don't believe it to be that critical however at 50K miles a good look see might be just what the doctor ordered.

Oemtech · 01-02-2009, 04:47 AM

Fulltimers,

The 4 plugs are not off one side. I think this is more coincidence than a case of indexing.

I also agree with DriVer in that I will not clean plugs like we use to back in the day. The cost of a set of plugs is not all that much.

Anyone want an air powered abrasive plug cleaner? I have one, its about 30 years old.

On edit- corrected spelling and grammar.

Bigdaddy · 01-06-2009, 04:51 AM

If I have no mods, what plug and what gap should I use. Have 45k miles and never had a problem with miss-fire. Have not checked plugs. But, on checking plugs, I might as well change them. Thanks in advance.