Community Forums

TAN · 12-11-2014, 02:39 PM

I just changed spark plugs. I put in 41-101 AC DELCO, but I took out 41-983 AC DELCO. I sure hope I put the right ones in? I removed the wheels so it would be easy to do. When I put the hub caps back on they didn't line up, turned out to be the hardest job of the hole process. I now have them figured out but will have forgot by the time I do it again. I also changed the wires. I had 55000 miles on the plugs. The wires and plugs had miles left in them but I changed them anyway.

Rocky Larson · 12-11-2014, 03:29 PM

I guess you can rest easy........Oemy's Web Site - AC Delco Spark Plugs

"007" · 12-11-2014, 04:27 PM

If the coach has the Brazels Ultra Power Upgrade the plugs are gapped at .45 instead of .60.
If you do not have it do not worry about it.
Re-gap helps with mileage.

TAN · 12-11-2014, 04:56 PM

I did gap them to .045. I hope I did that right? I have not done any upgrades to the motor.

vettenuts · 12-11-2014, 08:15 PM

I just installed the same spark plugs gapped to 0.045". I have read that GM changed the gap on the LS1 motor from 0.060" to 0.045" through a tech bulletin and felt comfortable running the same gap in the RV. (I run this smaller gap in my LS1.). I also went with the Magnum wires. I have the same mileage as you.

mgscott4 · 12-12-2014, 07:14 AM

Quote:

Originally Posted by vettenuts

I just installed the same spark plugs gapped to 0.045". I have read that GM changed the gap on the LS1 motor from 0.060" to 0.045" through a tech bulletin and felt comfortable running the same gap in the RV. (I run this smaller gap in my LS1.). I also went with the Magnum wires. I have the same mileage as you.

I don't care about Ultrapower or what spark plug gap to use with it.

Does anybody have any documentation, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045 not .060 ?

I do know that the 41-101 is the upgrade for the older 41-983 plugs. (Platinum to Iridium)

vettenuts · 12-12-2014, 07:50 PM

I do not have the Ultra Power. The smaller gap is fine and less prone to high RPM miss. Brazil also recommends the smaller gap.

mgscott4 · 12-12-2014, 07:53 PM

You and Brazil can recommend what ever you want.

I am not saying it doesn't help to have a different gap. It probably does. But,

My question is: Does anybody have any documentation, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045 not .060 ?

"007" · 12-12-2014, 09:40 PM

When Brazels set up their Ultra Power program they said to gap the plugs at .045, because that is what they set the program for, instead of the .060 normally gaped for 8.1.
If you do not have program leave gap alone.
Read this thread now say with out the UP program.

UP evaluation

mgscott4 · 12-13-2014, 07:28 AM

As I stated earlier, I don,t care what Brazel recommends.

Does anybody have any documentation, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045 not .060 ?

Maybe I am asking incorrectly.
Does anybody have any documentation from GM, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045?

That is all I want to know.

So it sounds like all this talk about re-gapping your spark plugs to .045 is because of one mechanical shop (garage) has had good results with there UP upgrade and it sounds like they programmed it to operate optimized at .045.

Oemtech · 12-15-2014, 07:32 PM

Quote:

Originally Posted by mgscott4

As I stated earlier, I don,t care what Brazel recommends.

Does anybody have any documentation, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045 not .060 ?

Maybe I am asking incorrectly.
Does anybody have any documentation from GM, not word of mouth, that the spark plug gap on a stock 8.1L engine should be .045?

That is all I want to know.

So it sounds like all this talk about re-gapping your spark plugs to .045 is because of one mechanical shop (garage) has had good results with there UP upgrade and it sounds like they programmed it to operate optimized at .045.

The .045 gap is the result of a lot of testing being done on a dyno and on the road R&D. Remember, that all of GM's specs are geared to pass government regulations and my not provide the best performance for a given application. The 8.1L engine was designed for a medium duty pickup truck.... not a 18,000 lb - 25,000 lb RV

But, to answer your question.... yes I have some doc that shows what the spec is for the spark plug.

vettenuts · 12-15-2014, 09:01 PM

I will still run the 0.045" in my coach. The larger gap was to help light throttle emissions but has resulted in high RPM misses that are not detected by the OBD II diagnostics.

max49 · 12-15-2014, 09:07 PM

Quote:

Originally Posted by oemtech

The .045 gap is the result of a lot of testing being done on a dyno and on the road R&D. Remember, that all of GM's specs are geared to pass government regulations and my not provide the best performance for a given application. The 8.1L engine was designed for a medium duty pickup truck.... not a 18,000 lb - 25,000 lb RV

But, to answer your question.... yes I have some doc that shows what the spec is for the spark plug.

but it says.060, I'll still go for.045, agreed, I believe the .060 and te 195* thermo are for best possible emission rather than best performance

mgscott4 · 12-15-2014, 09:21 PM

So bottom line, Workhorse recommends .060.

But

Quote
"The .045 gap is the result of a lot of testing being done on a dyno and on the road R&D. Remember, that all of GM's specs are geared to pass government regulations and my not provide the best performance for a given application. The 8.1L engine was designed for a medium duty pickup truck.... not a 18,000 lb - 25,000 lb RV"

I don't think i will try the .045 spark plug gap on my next plug change, right now my 41-101's at .060 are working great, at 110,000 miles, my fuel mileage is still just above 8 mpg, and my but dyno says my engine has just as much power as it did when it was new.

"If it ain't broke I ain't fixin it. But I might upgrade it.

Thanks again Oemy.