Spark Plugs which one??

[al koffman]

On Oemy's web site it calls for AC-983 plugs. In the 2004 Workhorse chassis manual it lists the plugs as AC-99321.

[oemtech]

Don't know where you read that.... But, you may want to read AC Delco Spark Plugs

The 41-983 is the stock plug gapped at .060.

The 41-932 was the replacement plug gapped at .045.

The 41-932 was replaced with the 42-993. Same plug just a different number. Just like the GF481 fuel filter that was renumbered to GF652.

[al koffman]

Thanks Dale, looks like I want is the 41-983 with a .045 gap. The 41-99321 which is what the 04 WH gas chassis manual lists must be a typo or whatever.

Just out of curiosity, why was the .060 gap changed to .045?

[DriVer]

Quote:

Originally Posted by al koffman Thanks Dale, looks like I want is the 41-983 with a .045 gap. Just out of curiosity, why was the .060 gap changed to .045?

al, The AC 41-983 is a direct OE replacement or your engine or it could be equipped with Denso plugs. Both of these platinum tipped plugs in a box stock engine should be gapped to .060.

A great many owners have chosen a alternate path and have engaged the use of aftermarket performace items such as Ultrapower. In these installations the AC Delco 41-993 platinum tipped spark plugs are used and gapped at .045.

To answer your question above, the gap has not been changed on the OE AC 41-983 plugs and it remains .060.

[oemtech]

Quote:

Originally Posted by al koffman Thanks Dale, looks like I want is the 41-983 with a .045 gap. The 41-99321 which is what the 04 WH gas chassis manual lists must be a typo or whatever. Just out of curiosity, why was the .060 gap changed to .045?

This a pretty common change.. a little hotter spark.

[DriVer]

Quote:

Originally Posted by oemtech This a pretty common change.. a little hotter spark.

Dale, Would you not agree that the words "spark plug" be added in front of "change"?

I hope that the OP is not receiving a bad message in trying to regap OE 41-983 plugs to .045. You and I both know if we're going to pull OE plugs that we're going to replace those with plugs that are gapped at .045.

[oemtech]

Quote:

Originally Posted by DriVer Dale, Would you not agree that the words "spark plug" be added in front of "change"? I hope that the OP is not receiving a bad message in trying to regap OE 41-983 plugs to .045. You and I both know if we're going to pull OE plugs that we're going to replace those with plugs that are gapped at .045.

Regapping spark plugs from .060 to .045 is a fairly common change with the hot rod guys. I plan to do it on my "new to me" 83 Monte Carlo SS.

When UltraPower first came out we regapped the 983's to .045. I have tested some NGK's gapped at .045 and they performed just fine. The only real way to tell with be comparison runs on a dyno.

[al koffman]

OK guys, let me put it this way. When I buy new plugs, 41-983, they will be gapped at .060, correct? Should I leave them there or re gap to .045, or will it really not matter for my engine with no changes?

Thanks to both of you.

[DriVer]

Quote:

Originally Posted by oemtech When UltraPower first came out we regapped the 983's to .045. I have tested some NGK's gapped at .045 and they performed just fine. The only real way to tell with be comparison runs on a dyno.

I think we have seen that done and it's the reason why 41-993s are used, it's all about the Dyno!

There's a PO unit IFO my house. The PD unit is an unmarked white PU/T. The POs are in civilian clothing with BPVs on w/ Police on the back. Roxy is going crazy barking and running back and forth.

[DriVer]

Quote:

Originally Posted by al koffman OK guys, let me put it this way. When I buy new plugs, 41-983, they will be gapped at .060, correct? Should I leave them there or re gap to .045, or will it really not matter for my engine with no changes?

If you have a box stock motor go with the 983 plugs. Make sure the gaps is set for .060 as I wouldn't trust the gaps to be accurate out of the box. Use an anti seize on the threads. Be careful pulling the spark plug wires off - there's a good chance that you will at least break one or two wires.

Good luck with your project.

■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■

This was my 13,000 Post !!

That was; One Baker's Dozen Thousand Posts! --- onward to 14K!

■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■ - ■

[oemtech]

Quote:

Originally Posted by DriVer There's a PO unit IFO my house. The PD unit is an unmarked white PU/T. The POs are in civilian clothing with BPVs on w/ Police on the back. Roxy is going crazy barking and running back and forth.

Pay the parking ticket next time!

[oemtech]

Quote:

Originally Posted by al koffman OK guys, let me put it this way. When I buy new plugs, 41-983, they will be gapped at .060, correct? Should I leave them there or re gap to .045, or will it really not matter for my engine with no changes? Thanks to both of you.

If you get them from me... pre-gapped at .045.

If you destroy a couple plug wires and don't plan to put a set of Taylors on let me know and I will ship you what you need for free. I think I have maybe 14 spares (stock Workhorse version).

[DriVer]

Quote:

Originally Posted by oemtech Pay the parking ticket next time!

Very werd! They made the driver of the stopped vehicle remove the garbage he had on the back deck under the glass and shove it in the trunk. I think they also gave him a ticket for obstructed vision. Must have been something for all that fracas -- there were 3 PD units on the scene. After all was said and done, .. the guy just got in his car and drove away....

[dieselclacker]

Maybe they just wanted to see what was in the trunk.

Dieselclacker