How not to bugger up your spark plug threads

As promised here is a guide on how not to bugger up your spark plug threads.

1st things1st always use a good anti seize compound on your spark plug treads, brush some on the plugs before you install them.

Use a proper spark plug socket some have a rubber boot to retain the plug in the socket, but I prefer ones that use a magnet to stop the plug from dropping out, it doesn't  sometimes pull out of the socket staying stuck on the plug insulator buried deep in a recess like rubber ones can.
The brand I use is Ampro. 
The ones I use the most have a swivel at the top of the socket that is permanently attached to a long extension bar. this bar being permanently attached wont leave the socket on the plug when you are installing it, leaving you trying to figure out how to recover the plug socket hidden deep in a recess!
These integrated extensions aren't always convenient in confined spaces so then I use a separate socket and a shorter extension that has a locking collar that keeps the socket locked attached to the socket until you pull back the release collar. this means you can always recover your socket.
For a ratchet handle I use one made especially for spark plugs, made by Champion (the spark plug company) the part number is CT500 these are designed to get in where others cant. I don't know if you can still get them, as I've had the 2 of mine for over 30yrs!

 
Pictured are various anti seize compounds I use depending on application and the plug socket and locking extension described above.
Don't waste you time on bloody great 1/2" drive sockets for spark plugs, you shouldn't need the strength and certainly don't need the bulk of those monsters, 3/8" drive sockets is all you should need.

When installing I start the treads by hand where possible and screw them all the way in by hand, only using the tools to nip them up.
But if the plug holes are heavily recessed I might use the socket and extension to carefully screw in the plug by hand and only put the handle on to nip it tight.
By screwing in the plug by hand you can easily feel if it's not treading right, so you stop, back it out and try again. but if you do it with a handle you risk damaging the thread before you realise you have a problem!
NEVER FORCE tighten a spark plug!

 
Another essential piece of workshop equipment is the kangaroo hide stock whip, this is used the flay the hide off on anyone caught force tightening spark plugs!
You have been warned!

 
Pictured is the installation of a plug in the head of a Leyland 4.4litre V8 using the socket with integrated swivel and extension by hand, not that this engine need it as the plughole aren't in deeply recessed pockets, I chose this engine for the pic as it is easier the show what I'm doing as the plugs aren't deeply recessed!

Another method of installing deeply recessed spark plugs is to use a bit of rubber hose slipped over the insulator of the plug and use this as a handle to hand screw in the plug, then as above use the tools to nip up the plug.
Any plugs that prove difficult to remove will require investigation as to why they're playing hard to get and may need helical thread inserts.
Some engine designs can be notorious for plugs breaking off leaving the threaded section stuck behind in the hole, a couple of these that spring to mind are the old pre crossflow Ford inline sixes found in Falcons, Mustangs etc. these featured a shallow thread with a taper seat and could seize something shocking, fortunately the weren't buried in deeply recessed pockets in the head so were relatively easy to get at, we all cheered when the crossflow heads came out and had normal plugs!
Unlike one of Ford's later efforts the 5.4 litre OHC V8! Every mechanic lives in abject fear of snapping off the plugs on these things!

 

Another corker. One question though; I was told to put the plug in “ clean & dry, plug & head”.
The procedure was, if the plug was new, clean the threads with a good solvent, good solvents could be bought then, (trichloroethane, carbon tetrachloride etc).
If out for a regap, wire brush, preferably rotary, in a lathe even better. Whilst out poke any lead* deposits off the central insulator, tap the electrode on a vice to close the gap & use a proper regapping tool to open up to the correct value.
Clean the head threads with a bottle brush & solvent until it comes out clean.
Then follow Cobber’s guide.
* for our younger viewers; white lead deposits formed on the plug, pistons & valves. Great fun & not at all dangerous.
M

Remember the old Champion Spark plug machines, every mechanic's shop had one, they would grit blast the plug to clean it and they could be used to test the plug too.

 

Back in those days the centre electrode was solid and could withstand such rough treatment, but plug technology moved on to copper cored centre electrodes etc. and even more exotic materials such as gold/palladium and platinum. Plugs of these types wouldn't tolerate such treatment, the removal of lead from the fuel and the fact that it became more cost effective to not bother spending time buggerising about with plugs and to just replace them instead. All these factors conspired to render the poor old Champion spark plug machine obsolete, and the survivors lay about as display pieces of garagenalia for collectors. There are even collectors of vintage spark plugs, these guys avidly seek out NOS plugs from ancient workshop clearing sales, and swap meets! 

In fact it probably sat next to another blast from the past, the Churchill Hydralastic suspension machine in the 1960's workshop!
 

 Ah yes, a prototype Dalek.

wrote:

 Ah yes, a prototype Dalek.

 

Yeah they do resemble something the BBC props department cooked up for DR Who.

Even though such a device would still be relevant to us MGF owners, they are by and large obsolete. The problem with these things is that you had to take the car to them, as they are a bit too awkward to move about, which would mean a game of automotive musical chairs would ensue every time you needed it.
Resulting in the disruption of having to move cars about the crowded busy workshop, it's far more convenient to use one of the more modern portable suspension pumps and carry it to the car.

Well well we’ll, & ha ha ha! It’s a long time since I have seen a Dalek.
I had one a goodly time ago & it was simply too unwieldy in the garage, every time I bent down in the store one of those arms would endeavour to damage some part of my anatomy.
I sold it to a chap who had an unhealthy interest in early 1100’s, Maxi’s etc, I bought a smaller model which up til now hasn’t made any attempt to injure me.
It’s good to become reacquainted with the thing. We’re they green, mine wasn’t by the time it arrived at my door.
M

Some were grey, but green was the most common here in OZ at least when new, they all ended up a fetching shade of filth.

Yes, my example was the latter colour, although as the previous owner had it near the paint shop, it also had a homage to all the grim paint colour used by BL over a number of years. It was “cheep rattle can blue” when it left.
M

When I was a younger man we used to use an old plug with a groove filed into the thread to remove any build ups on both 2 stroke motor cycles and then as we graduated to cars, used the same procedure on those.
Always done a good job especially on the ally heads of the M/Cycles. I still do the same now and showed my Son now he does it also.

Ah wonderful, the old grooved plug stunt. I inherited a two set but fortunately never needed to use them. One had a single groove, starting at the second or third thread, this allowed for certain indexing with the head.
Number two plug had four grooves diametrically opposed to each other. A couple of petrol soaked pipe cleaners would be placed over the tip & run down the groove to clean out any dirt left in the threads as it was screwed in. I’ve no idea where they are now.
On Cobber’s comment on plug collectors; the place to go if your fetish is spark plugs is the Shuttleworth Collection at Old Warden airfield near Biggleswade. Here there are display cases full of every conceivable type. The entire collection is worth a visit or two.
Whilst tractor technology was little more than a four wheeled mechanical horse, the plugs had to be regularly removed, stripped & cleaned, especially if the engine was using TVO. A bit of a fag for an agrarian whose life had been spent looking up the arse of a horse.
To digress. It’s bloody cold up here, bloody cold. I went to bring some logs down from the top store, when I tripped over a hose pipe I didn’t know I had. It turn out to be a piece of heat shrink I’d dropped the other day.
M

I can remember an old farmer in the area where I lived as a boy who done most of his daily work with a horse, but he had a really old odd tractor that was started with what looked like a 12 bore cartridge that was put into the engine, made secure and I think it was hit with a hammer to get it started.

Yes, they were the Field Marshall & they did use a shotgun cartridge, obviously without the shot.
The engine would be primed & arrange to be just after TDC, the cartridge inserted, a cap cover dropped over the firing pin & WAP, away it would go.
Brilliant, I don’t recall ever seeing one failing to start.
A German company Lanz used a hot bulb to atomise the fuel, before starting. A fire would be lit under the bulb if the blow lamp (provided) couldn’t get it hot enough.
Mainly a winter problem.
M