AC spark plug for our 78 403

[Bob Dunahugh]

When the PO put AC plugs in. R46SX plugs were installed. According to a shop manual that I have. The correct plug for the 403 is R46SZ. I'm not up on the meaning of the X, and Z. I'm sticking with the AC plugs. Bob Dunahugh

 

[emerystora]

According to plug information I have the R46SZ replaced the R46SX. The SX's were gapped for .080 and the SZ was gapped at .060. Only difference. Just bend your tab on an SX and make it work. However the current thinking is that a .038 gas is better with the hei system.

Emery Stora

>
> When the PO put AC plugs in. R46SX plugs were installed. According to a shop manual that I have. The correct plug for the 403 is R46SZ. I'm not up on the meaning of the X, and Z. I'm sticking with the AC plugs. Bob Dunahugh
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[CGeils]

FYI ACDelco still offers the R45S plug. This is gapped at .040 and "45" is one heat range colder than the R46SX.
--
Chris Geils - Twin Cities
1978 26' Kingsley w/ very few mods; Headers, Progressive Dynamics 9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, 50k mi

 

[Bob Dunahugh]

The 46 heat range seemed hot to me. But the plugs that I remove looked the perfect color as to heat. They have about 12,000 miles on them. I'll put new ones in anyway. And I want to index them trod the combustion chamber to alien the flame front. Not a big thing. Just me being anile with details.

________________________________
From: Bob Dunahugh
Sent: Thursday, November 23, 2017 6:55 PM
To: gmclist
Subject: AC spark plug for our 78 403

When the PO put AC plugs in. R46SX plugs were installed. According to a shop manual that I have. The correct plug for the 403 is R46SZ. I'm not up on the meaning of the X, and Z. I'm sticking with the AC plugs. Bob Dunahugh

 

[wrightjohn 2646]

Gentlemen,
There is a spark plug chart that has been published in the GMCMI parts interchange and available here:

http://www.gmcmhphotos.com/photos/data/5237/Spark_Plug_Application_Guide.pdf

Altho this was done in 2013 there has been no real updates in plugs available since then.

JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan

>
> The 46 heat range seemed hot to me. But the plugs that I remove looked the perfect color as to heat. They have about 12,000 miles on them. I'll put new ones in anyway. And I want to index them trod the combustion chamber to alien the flame front. Not a big thing. Just me being anile with details.
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Thursday, November 23, 2017 6:55 PM
> To: gmclist
> Subject: AC spark plug for our 78 403
>
>
> When the PO put AC plugs in. R46SX plugs were installed. According to a shop manual that I have. The correct plug for the 403 is R46SZ. I'm not up on the meaning of the X, and Z. I'm sticking with the AC plugs. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[john r. lebetski]

I thought R45S was correct --are those discon? My understanding was the x was long reach electrodes
--
John Lebetski
Woodstock, IL
77 Eleganza II