Spark Plug Sockets

[rebelram]

I've been lurking here for about a week. There is an enormous amount of knowledge on these boards! Like most of you, I have a wide variety of tools in my collection.

Here's my question, all spark plug sockets have a nut molded into the top of the socket. Why? For use when a ratchet doesn't have enough clearance? That's the only logical explanation I could come up with. I find that most of the time I'm using an extension and a flex adapter when changing spark plugs. The only other use I have found for the spark plug socket design is the molded nut does make those sockets easier to find in the toolbox.

Also I saw in the Craftsman catalog they now list an 18mm spark plug socket. I have yet to run into an 18mm spark plug. Any American car companies using that size spark plug yet?

 

[Jbullfrog]

the hex is for the plugs on the firewall side of transverse mounted engines, where you can't get a ratchet and socket extracted with the plug.

 

[chammyman]

motorbikes use the 18mm sized ones.

Although its hard to know what they mean when they say 18mm as they use silly sizes like the 10mm plug sockets have a 16mm hex and the 22mm hex ones have the 14mm thread.

but yes its for clearence, often on quads and bikes you only haveroom for the socket and a spanner then need to bend your fingers 5 different ways after breakign them so you can do that to unscrew them!

 

[wantedabiggergarage]

I've seen a few things done in my time. Don't have an extension handy, use a socket on that socket, use a gear (or regular) wrench (their is even a very small version of this for tight fitting engine compartments around headers).

They also have some longer spark plug sockets, and those with a gearwrench do work well in things like vans (PITAccess). Snap~on was the only one that I knew/looked at, that didn't have the hex end. That was why I didn't buy it, you try to leave yourself options, for those times when you need something else to work.

 

[plinker]

A Honda 250 motor uses a 18mm spark plug socket.

 

[rsanter]

on several vintage big block cars, you will need to put a wrench on that spark plug socket to get those plugs out

bob

 

[wantedabiggergarage]

the hex is for the plugs on the firewall side of transverse mounted engines, where you can't get a ratchet and socket extracted with the plug.

It can be useful for that, but it isn't because of that. Look at the old tools and you will see it was already there, yet we weren't using transverse mounted engines much. (not counting things like a Tucker)

 

[rebelram]

I guess that brings up the next question of when was the hex added to the top of spark plug sockets? I have used a couple spark plug sockets that are at least 50 years old and they had them as well. Since both my dad and my grandpa were auto mechanics I've had the opportunity to learn a lot from them as well as use the really old tools they collected over the years. Oldest thing I ever changed a spark plug in was a 1938 John Deere Model L. Last transverse engine I changed spark plugs on was a 3.0L Dodge Stratus. Not bad, but you have to pull the plenum intake to get to back 3 plugs. Fortunately they were down in the center of the valve covers so all you needed was a socket and extension.

 

[ImportTuner]

the hex is for the plugs on the firewall side of transverse mounted engines, where you can't get a ratchet and socket extracted with the plug.

Yep, what Jbullfrog said ...

 

[Thumper]

Also useful when the engine has headers.

 

[Hip2u77]

Also useful when the engine has headers.

Exactly what I was thinking also.

Seems like I had to use the hex with an off-set box wrench to change one of the plugs in my old '77 Chevy Monza. It had a 350 with 5 piece ****** Super-comp headers.

 

[Egghaus]

Also useful when the engine has headers

The hex is very useful on a small block with headers in a small car. In my Nova, one plug on each side has the header tube crossing directly in front of it, so it is impossible to use a ratchet and extension.

 

[eschoendorff]

on several vintage big block cars, you will need to put a wrench on that spark plug socket to get those plugs out

bob

A flex head GearWrench on a spark plug socket gets it done everytime!

 

[Fedwrench]

The hex also makes finger spinning when starting the plug alot easier.

 

[Elroy]

The hex also makes finger spinning when starting the plug alot easier.

That may be but a short piece of 3/8 fuel line works wonders.

 

[Elroy]

.....all spark plug sockets have a nut molded into the top of the socket. Why?

That is not completely true as Elroy offer you this spark plug socket to consider:

 

[Frank Elson]

I have always assumed it was for easier finger spinning. That's what I use it for anyway.

 

[rebelram]

You're right! And my dad has that exact 13/16 Snap On Flex socket. It's the only one I have ever seen like that. Works very well too. I guess other manufacturers make a similar item.

 

[posaune]

A flex head GearWrench on a spark plug socket gets it done everytime!

Not to threadjack, but speaking of that, THIS (Gearwrench ratchet and sparkplug sockets for $37) seems like it might be a good deal. That ratchet alone goes for more usually.

 

[lauver]

Since the sparkplug socket with hex design predates big blocks, headers, and transverse mounted engines, and appeared at a time when most cars had inline 6 cylinder engines, it could be that the hex was not about clearance. It could be that the hex was to make the socket usable to all the folks who didn't have ratchets. All you needed to drive the sparkplug socket was a crescent, open end, or box end wrench, all of which were fairly common. In my case, I owned a sparkplug socket years before I owned a ratchet and other sockets. I have also seen many a sparkplug socket that had a hole drilled across the top of the socket so you could slip a screwdriver thru the socket to tighten the sparkplug.

Now the fact that the hex feature also happens to make the sparkplug socket useful in low clearance situations may be the reason why the hex feature has persisted all these years.

Just my observations.

 

[rebelram]

So when I got home from work today, I decided to check a little more on the hex heads of the sockets. What I found was very interesting.

For spark plug sockets I have the following:

Stanley 3/8 drive in 5/8, 3/4, and 13/16
Craftsman 1/2 drive in 5/8 and 13/16

For the Stanley 5/8 and 3/4 the hex needed a 19mm wrench
For the Stanley 13/16 and Craftsman 13/16 the hex needed a 22mm wrench
For the Craftsman 5/8 the hex needed a 13/16 wrench

It really surprised me that metric wrenches were needed on SAE sockets. I checked them against similar sized SAE wrenches and the 19 and 22 were a better tighter fit.

 

[Elroy]

19mm is .74803" so guess what.

and 22mm is with-in a 1/64" of 7/8". These sockets were designed for English "spanners"

 

[Lightning]

I have the 5/8 Snap On magnetic spark plug socket. It has a hex on top.