Which Spark Plug and Gap????

[Capt Joe]

Thought while I was messing around in the engine compartment that I'd go on and change my plugs. Been reading a lot of old posts about the different plugs being used...41-932/933/983/993 etc and gaps from .045 to .065 and it gets confusing.

Anybody give an up to date plug and gap that would be preferred in my 2003 8.1 (no modifications...completely stock) to give max power and mileage?

Thanks greatly...Hope to get it buttoned up tomorrow so we can take a little ride on Wed.

[LVJ58]

If it's running OK and no engine miss, I highly recommend leave it alone. Spark plugs in today's engines, usually last up to 100k miles. Newer ignition systems put out higher voltage but less amperage to burn the electrodes.

I have read a few posts where folks experienced burnt plug wires with some 8.1 engines.

I strongly subscribe to that old saying, "If it works, leave it alone" "If it's broke, fix it."

Happy & safe travels

[JonBrazel]

We recommend, and use, the 41-932 plug gapped at .045

[Capt Joe]

Jon,
Thanks for the reply. What is the difference in the 932 and the 933 plugs. The local NAPA has the 933's only.
Will the .045 gap work in a non-modified 8.1 to give better response, power and hopefully a bit better mileage?

[JonBrazel]

Yeah, I believe the 933's will work fine. The power and mileage increase will be negligible, but we have dyno tested this setup on a stock engine and seen an increase of around 3 HP. To get a seat of the pants increase in performance you will have to do something more, such as UltraPower or air modifications.

[oemtech]

Yep, the plugs will probably run 100,000 miles BUT... They can be a real PAIN to remove at that mileage. Here is a set with 78,000 miles on them.



Here is a comparison of NEW at .045 and OLD at .060.

[sknight]

The 100,000 mile part is deceiving. Yes they can go 100K in a car easily. But consider the life your engine has. It lives working at 50-80% compared to a passenger car cruising at 25-50%. It working harder means shorter life for the plugs.

Despite what commercials tell you just changing plugs won't give you better power or mileage. The gains that most people see is from installing new plugs after their old ones have pretty much given up the ghost. You can swap out ten different sets of new plugs and see a five HP difference between them, and your 8.1 may react different compared to another 8.1 with the same plugs.

[Bigdaddy]

If you can change the plugs, DO it! At 43K miles, mine looked like the pictures of the used plugs. BTY, I did pick about 1MPG.

[Jeepster47]

oemtech,

Those old plugs look like there from Ed G's 8.1 engine.

Ed H.

[DriVer]

Quote:

Originally Posted by Jeepster47 Those old plugs look like there from Ed G's 8.1 engine.

Na couldn't be! They just look old and crusty "like" Ed.

[oemtech]

Yuppers... "OLD" ED made the contribution to Oemy's Rogues Photo Gallery

[Gregg]

Guys,
Now I'm confused,
Jon said, "We recommend, and use, the 41-932 plug gapped at .045 "
I thought the "41-932" was discontinued and the new recommendation was the
"41-993" ??

[DriVer]

Quote:

Originally Posted by Gregg Jon said, "We recommend, and use, the 41-932 plug gapped at .045 " I thought the "41-932" was discontinued and the new recommendation was the "41-993" ??

Gregg, You're right. That said, if you have a ton of 932s in stock, there's no need to throw them out. If you go to NAPA and ask for a 932 they will give you a 993.

[Gregg]

Thanks DriVer !!