| [GMCnet] Newest, bestest spark plugs? [message #255009] |
Thu, 10 July 2014 19:35  |
kelvin
Messages: 608
Registered: February 2004
Location: Eugene, OR
Karma: 0
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So what's the latest answer to, "Which spark plug should I use?"
455 in the '73. I've been using AC Delco R46SZ since 2005. 20,000
miles on them so it's probably time to swap 'em. Haven't pulled them out
yet but they've gotta be a bit rounded. I'm happy with these plugs but
willing to entertain other ideas.
Kelvin
'73 23' in Eugene, OR
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| Re: [GMCnet] Newest, bestest spark plugs? [message #255012 is a reply to message #255010] |
Thu, 10 July 2014 19:55  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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As recommended by Dick Paterson, NGK XR51X (7355), gapped at 0.038.
The combination of Dick's Distributor, Ignition Wies and these plugs sure woke up my 455.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] Newest, bestest spark plugs? [message #255029 is a reply to message #255012] |
Thu, 10 July 2014 22:27 |
kelvin
Messages: 608
Registered: February 2004
Location: Eugene, OR
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On 7/10/2014 5:55 PM, Thomas Phipps wrote:
> As recommended by Dick Paterson, NGK XR51X (7355), gapped at 0.038.
> The combination of Dick's Distributor, Ignition Wies and these plugs sure woke up my 455.
> Tom, MS II
Installed one of his distributors and a set of his wires in 2003. The
first best thing I did for the mileage. If I had a rebuildable GMC
Q-Jet I'd have one of his carbs, too.
I think I'll take his advice on the plugs. Besides, I swear by NGKs in
my Datsun so that's kind of proper.
Kelvin
'73 23' and '71 510 in Eugene, OR
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| Re: [GMCnet] Newest, bestest spark plugs? [message #255030 is a reply to message #255009] |
Thu, 10 July 2014 23:22 |
mrgmc3
Messages: 210
Registered: September 2013
Location: W Washington
Karma: 2
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Kelvin Dietz wrote on Thu, 10 July 2014 19:35So what's the latest answer to, "Which spark plug should I use?"
455 in the '73. I've been using AC Delco R46SZ since 2005. 20,000
miles on them so it's probably time to swap 'em.
I would recommend going with a heat range colder, that is to an R45SZ. The heat range is a compromise between cold fouling on one end and resistance to pre-ignition on the other. Since almost none of us need worry about cold fouling (the reason for a higher heat range) then it is a good idea to get more margin from potential pre-ignition by going a range or two colder.
Chris Geils - Twin Cities / W Wa
1978 26' Kingsley w/ very few mods; PD9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, Alcoas, 54k mi
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| Re: [GMCnet] Newest, bestest spark plugs? [message #255057 is a reply to message #255029] |
Fri, 11 July 2014 10:03 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Kelvin,
I just replaced my 22,000 mile AC/Delco plugs with the recommended NGK Iridium tipped plugs. I got them from Jim K, didn't pay attention to the price. I'm not sure I really needed to install 100,000 mile spark plugs in an engine with 88,000 miles on it. I guess I can reuse them in the rebuild in a couple of years if it comes to that.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Newest, bestest spark plugs? [message #255086 is a reply to message #255009] |
Fri, 11 July 2014 14:58 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Back in the late 60's early 70's I worked at the High Performance Center...a hot rod shop...in Milwaukee. Did all of they're balancing and a lot of engine assembly. We had a 67 Camaro that just had a HP 427 that we ran on a chasse dyno with four major brands of spark plugs and one off brand. This motor was putting out close to 600hp. Ran is so hard that I thought it was going to jump of the dyno and end up out the front window into the street. We found no difference in HP output between the plugs accept we noted that Autolites were less likely to misfire at extreme RPM and load than all of the others. This was only under extreme conditions, something that we would never see with our MH's. I'm not convinced that it makes any difference what brand of plug you run as long is it is the right heat range for the application. That being said, I'd sure like to hear from Dick Paterson about his experience with plug brands. Maybe I'll ask him about that at the Wisconsin rally.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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