Re: Spark Plug Query
 

http://uploads.tapatalk-cdn.com/2016...5e3484e960.jpg

#2

Is there an issue? Or do I just live with 2 different styles of plugs?

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Re: Spark Plug Query
 

Let's not worry about what I want to hear LOL I'm happy to keep digging

I completely agree.... it was weird enough that at first I was just assuming that I was having a moment.

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.

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.

Completely understand. I spent a couple of hours last night going over it again and again, because it just doesn't make sense.





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.

Re: Spark Plug Query
 

I thought you were asleep and was re writing my post when you posted, that's why it's gone. But you have it quoted. I see it's 5:30PM there, sorry.

It is possible that you have a tapered head with non tapered plugs that "seems" to fit. That is what we are both thinking. That's what Turbobill said way back. If that is possible, you don't want that. Others will chime in tomorrow. BigBlockV6 has a post talking about tapered for larger motors. D10 plug.

ALSO: Your spark plug hole picture does not look right at all for 305. Is that a weld fillet holding in an insert or greasy spot painted orange? What the **** is that? It's either what Big V6's look like or it's a fix. That's what FMAP said way back. Show a hole in the other head.

Thanks to K:champagne: for asking for a picture.

Re: Spark Plug Query
 

http://uploads.tapatalk-cdn.com/2016...2624fe1bdf.jpg enlarged picture of the #2 (one of the ones that won't take the short plug [all 3 look the same]

http://uploads.tapatalk-cdn.com/2016...8320f99745.jpg
Enlarged picture of #1 (one of the 3 that will take the short plug [all 3 look the same]

I can see now that the difference is that the even cylinders are inset. So the short er plug won't ever work because the threads won't reach.


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Re: Spark Plug Query
 

It look like sometime in the truck past a head was change out.You might want to make sure the threads in the heads is the same length as the spark plug reach. If the long reach plug is place in a hole design for a head with a short reach the expose threads could cause a couple of problems. It could have a build up of carbon making it difficult to remove the next time and/or could create a hot spot in the combustion chamber and pre-ignite the fuel charge (cause spark knock and loss of power).

My truck heads required the long reach but only the tip half of the plug is threaded into the head. They use to make plugs this way but decided to do away with them to cut their inventory (see picture). I also have two spare set of heads. One is made like the one in my truck the other is machine for a short reach plug.

Re: Spark Plug Query
 

I can't tell for certain from the picture. But, it looks like the older style plug doesn't have a metal gasket on it, is that correct?

The reason why I'm asking is I'm trying to work out whether or not the plug I need has a tapered or a gasket seat. Is there some way that I can tell by looking at the plug hole?

Re: Spark Plug Query
 

Your pictures show the head seat area very dirty, however it look like both of them is taper. Can you clean it up a little better and see if they match one of the pictures?

Looking at my pictures (of my spare heads) the long reach has a squared off seat. The short reach has a taper seat.

Re: Spark Plug Query
 

Yes that plug picture is a taper seat plug. The pencil is pointing at the taper.

Re: Spark Plug Query
 

It is a bit atrocious how dirty they are. I hit them with some air while the old spark plugs were in. But, it clearly didn't do the trick.

What have you used to get yours so clean? I'm super paranoid about letting anything fall through into the chamber.

Re: Spark Plug Query
 

I use an awl, the one you normally would see with a 90° bend on one tip and the other end is straight with the plug install about half way in, and scrap around the plug. Then I use a air nozzle with a long small snout to blow out all loose debris. Then I removed the spark plug and insert a rag large enough to plug the hole and finish cleaning and blowing it off.