AC Delco Spark Plugs

[Father Mulcahy]

Dale on your web-site you mentioned 993 plugs should be gapped at .045 if you have ultrapower installed. I recently put the 993's in our motorhome. I have had ultrapower on board since 2005. Motorhome has 49,000 miles and runs great, however I thought it would be best to change out the old plugs. They looked just like the Denso plugs on your site, wore out, gap above 60. With the new 993's in gapped at .045 my Butt Dyno feels like I have lost some get up and go. Motor is running fine, just seems less power with change to new plugs.

Ultrapower gap is .045 correct.

[Brazel's RV Performance]

You may have a loose spark plug wire, I'd start by going back through and making sure they are all tight on the plug.

[Father Mulcahy]

Jon, thanks for you advice. I will re check wires. As I mentioned the motor is idling very smooth and there does not seem to be a miss even on acceleration. If a wire is not on correct, would I notice ruff idle or miss?

[Oemtech]

Originally Posted by Father Mulcahy

Dale on your web-site you mentioned 993 plugs should be gapped at .045 if you have ultrapower installed. I recently put the 993's in our motorhome. I have had ultrapower on board since 2005. Motorhome has 49,000 miles and runs great, however I thought it would be best to change out the old plugs. They looked just like the Denso plugs on your site, wore out, gap above 60. With the new 993's in gapped at .045 my Butt Dyno feels like I have lost some get up and go. Motor is running fine, just seems less power with change to new plugs.

Ultrapower gap is .045 correct.

Say 2 Hail Mary's, Light a Candle, Put $5 in the Poor Box, Take 2 Asprin and call me in the morning. Almost forgot... get the Butt Dyno calibrated.

As Jon said recheck your wires. You should a audible click when they seat, both ends. You may not here a mis until the gap between the plug a wire gets fairly large.

Of course you can always pull the plugs and re-gap them to .060 for a test run.

[KSDP]

At how many miles should the plugs be changed? I have 26,000 on our 2005.

[DriVer]

Originally Posted by KSDP

At how many miles should the plugs be changed? I have 26,000 on our 2005.

The plugs are rated for 100,000 miles however I'm on my 3rd set at 64,000 miles. If that is any indication, change your plugs at 50,000 miles. You have a ways to go yet!

[Oemtech]

Originally Posted by KSDP

At how many miles should the plugs be changed? I have 26,000 on our 2005.

As DriVer say 100,000 is what GM/Workhorse say. But, in the real world 30,000 would not be to early. I would pull a couple and check.

Remember GM/Workhorse does not put "Never Seize" on the plugs and I have had some take a bit of work to get out.

Here is a set with 78k on them and a some new ones. Which set do you want in your motor?

[Rockybird]

Since we are talking about spark plugs, I have a question.

I have purchased a new set of plugs (993’s) and will be installing them sometime next week.

I do not have the ultrapower upgrade on my coach, but did have the Banks exhaust system installed without the chip.

My question is what should I gap the new plugs at 0.60 or 0.45???

[Oemtech]

Me I would gap them at .045.

[DriVer]

Originally Posted by Rockybird

My question is what should I gap the new plugs at 0.60 or 0.45???

I would not disagree with Oemy's preference however unless you have a specific need, the plugs should be gapped at the OE recommendation of .060 unless the plugs are a component of a performance upgrade that may require the .045 gap recommendation.

[Full-Timers]

I think Jon Brazel should do a Dyno on these new plugs.

[Oemtech]

That test has already been run. Remember the 993 was the replacement for the 932. The 932 plug was use in a Dyno test that resulted in the .045 gap for that plug.

[max49]

Dale, is there a "colder" plug that will work with the 8.1? My Mh sits alot but when it goes, it works hard almost always going into or across the Rockies. With my burning plug wire problem and obvious high heat in the exhaust manifold area, a 'colder range' plug could'nt hurt any thing.
A lot of the motorcycles and even my Champion Generator recomend different heat range plugs for differernt operating conditions.
All of my motorcycles give different heat range plug options and even the Iridium plug option but I believe the Iridiums are about 3 or2X more money

[DriVer]

Originally Posted by max49

... With my burning plug wire problem and obvious high heat in the exhaust manifold area, a 'colder range' plug couldn't hurt any thing.

Max, Just because you get a colder range plug doesn't necessarily mean that you are going to physically run any cooler and keep from frying wires.

What you need are fewer mountains ...