Quote:
Originally Posted by AZKen
You have to analyze this problem before we can rest. Before we will answer. I know you want to hear to just use them. Go ahead if you do not want to know what is wrong.
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Let's not worry about what I want to hear LOL I'm happy to keep digging
Quote:
Originally Posted by AZKen
If the two different plugs have the same 14mm and one fits and the other does not and the one that does not is short, it has to thread in. It makes absolutely no sense.
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I completely agree.... it was weird enough that at first I was just assuming that I was having a moment.
Quote:
Originally Posted by AZKen
Is the reason it won't "fit" is that the threads won't start? or the hex on the plug hits the casting? or your wrench hits or what????? Are you saying it's too short to reach the first thread in the head????
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Most of this is by feel, because I can't see anything. But, the best way that I can think of to describe it is that the plug just free spins. Considering that longer plugs I had in were also 14mm, and they went in fine, logic is telling me it's got to be that the shorter ones are just to short.
Quote:
Originally Posted by AZKen
do the threads in the head look odd? like a helicoil or some repair plug???
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The photo that I took is the best look I've actually been able to have.... But, nothing looks glaringly wrong. When I look at the threads on the plugs that I've pulled (the long ones that fit) they don't look damaged or anything like that.
Quote:
Originally Posted by AZKen
Can you understand that from here it seems impossible if all plugs have the same pitch/size thread? 14mm.
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Completely understand. I spent a couple of hours last night going over it again and again, because it just doesn't make sense.
Quote:
Originally Posted by AZKen
This seems to indicate a different plug, tapered seat?. I got the feeling it is different mechanically not just spark. Guess what? the Delco 10 has 14mm threads also and is a tad longer than 3/8. If by taper they mean "different" thread shape than 305 plugs, then you could have some heads from the larger motors (if they even fit). If you are using a "normal" plug in a head that is built for taper (whatever that means)
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Some digging on the NGK site has provided some clarity.....
https://www.ngk.com/product.aspx?zpid=9371
It looks like the tapered seat (which apparently is all about how it makes a seal) can come in the same pitch and thread size as the gasket style plugs. They're not interchangeable.