Spark plug "reach" 440 with 915 heads
#1124569
11/30/11 07:19 PM
11/30/11 07:19 PM
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HelleOnWheels
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I am trying to understand spark plug "reach" and which plugs I can use in my mostly stock 440 with 915 heads. When I check for plugs at Napa/Autozone/etc, I am given a wide range of plugs that come up when searching my car in the system. Some of them have a longer reach and some have a shorter reach. I am concerned with them reaching too far in and possibly causing damage. 1. What plugs should I be running? 2. Is there any performance difference with longer vs shorter reaching plugs? I have read many posts on here about this but most of them talk about modified motors/heads. 
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Re: Spark plug "reach" 440 with 915 heads
[Re: mikemee1331]
#1124572
11/30/11 10:29 PM
11/30/11 10:29 PM
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Posts: 228
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HelleOnWheels
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Quote:
you just need a stock length plug. autolite or NGK are good plugs. i have modified 906 heads on my 440 i use a stock plug. my mods are all to the ports. autolite 85
Are these the 2 plugs you are referencing? Is there any reason to buy NGK over Autolite?
http://www.summitracing.com/compare.aspx
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Re: Spark plug "reach" 440 with 915 heads
[Re: mikemee1331]
#1124574
11/30/11 11:11 PM
11/30/11 11:11 PM
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HelleOnWheels
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Quote:
your link goes nowhere. you don't need Summit, just any parts store in your area. i've never used NGK, just read what people here have said. i've only ever used autolite, why mess with something that works. you will of course now get a hundred different opinions but i'm cool with autolite.
I wasn't going to buy them from Summit. I was just comparing the 2 plugs side by side using their website. My local parts place has the 85's and the NGK3332's available. I will probably use whichever one is in stock when I arrive:)
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Re: Spark plug "reach" 440 with 915 heads
[Re: lewtot184]
#1124576
12/01/11 11:55 AM
12/01/11 11:55 AM
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Joined: Jan 2003
Posts: 16,376
dogdays
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The reach is the distance from the seat to the end of the threads. Most B/RB engines use a 3/8" reach gasketed plug, 14mm thread diameter. These are also used in 318 Polys.
Other plugs that you can't use are 3/8" reach tapered, also called "peanut plugs", and 3/4" reach plugs in both tapered and gasketed. LA motors, for example, use a 3/4" reach gasketed plug.
I have found many varieties of 3/8" gasketed plugs. At a swap meet I found a box of 50 RJ18YC which are a real hot plug that work well in my oil-burning Poly. I have also bought Bosch Platinum + plugs.
Autolite 85 and 86 work, and I have had really good luck with AC plugs, I think R44TS.
I think you are always better off with an extended tip spark plug if it will fit in your engine and not hit the piston.
Spark plugs are not magic, but some do work better than others. This may depend on your individual engine or driving habits. Don't be afraid to experiment.
R.
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Re: Spark plug "reach" 440 with 915 heads
[Re: Cab_Burge]
#1124577
12/01/11 12:00 PM
12/01/11 12:00 PM
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Joined: Jan 2003
Posts: 7,861
Witness Protection Program
Kudakidd
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Quote:
The Autolite 85 is a resitor plug and it is the hottest one made by Autolite, I think  I would probally want to try the Autolite # 84 or # 74(non resistor) with those heads, especially if the compression ratio is going to be close to 9.5 to 1 or higher 
 but try finding a non resistor Autolite 75 or 74. They're like hen's teeth!
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Re: Spark plug "reach" 440 with 915 heads
[Re: HelleOnWheels]
#1124579
12/01/11 12:21 PM
12/01/11 12:21 PM
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Posts: 75,082
U.S.S.A.
JohnRR
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I Win
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Quote:
Quote:
you just need a stock length plug. autolite or NGK are good plugs. i have modified 906 heads on my 440 i use a stock plug. my mods are all to the ports. autolite 85
Are these the 2 plugs you are referencing? Is there any reason to buy NGK over Autolite?
Maybe , the standard Autolites have now been outsourced to largest country in Aisa for production and there quality is questionable.
If you want Autolites buy the race plug version, they are at least made on this continent.
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