Quick question: What size plug spanner/socket?

[Chris71]

As per the title, does anyone know what size plug socket I need for the Rover V8?

[dog man]

Think they're just a 14mm ''plug socket'' they tend to be one of two sizes so you cant go too far wrong, the other is smaller

[Chimpafrolic]

dog man said:

Think they're just a 14mm ''plug socket'' they tend to be one of two sizes so you cant go too far wrong, the other is smaller

14mm is the thread size, the hex is 21mm so the socket you need is 21mm.

[Chris71]

Thanks gents. Off to Halfords!

Managed to locate the various plugs for the lambda sensor, but still couldn't get any contact on them with the rather stubby probes on my multimeter, so I'm just going for a plug check and air filter clean today.

[Chimpafrolic]

Vintage stuff aside there are three main (hex) sizes of spark plug.

1) 16mm (mostly motorcycle)

2) 18mm (mostly motorcycle but some cars)

3) 21mm (mostly car)

Your plugs are the 21mm type.

Actually the plug socket you require is 13/16" and ideally you need a thin walled one on a 3/8" drive.

But these days they are nearly always stamped as 21mm because its more or less the same thing.

13/16" = 0.8125
21mm = 0.8267716527

The plugs to use are: NGKB7ECS

Thread Diameter:14mm
Thread Reach: 19mm
Seat Type: flat
Hex Size: 21mm
Tip configuration: non projected
Construction/note: Short ground electrode
Terminal Type: Removable

When removing the old plugs its a good idea to spray some penetrating fluid into the plug recesses and let it soak for an hour (perhaps while you are changing the air filter).

When fitting your new plugs be careful not to cross thread or over tighten them, start them in the thread by hand first.

They should screw in freely a turn or two by hand before you need to use your socket.

If you are in any doubt and you have access to a torque 3/8" wrench, torque the plugs to 18 lbs.

If you are unlucky enough to cross thread a plug or the threads have been abused in the past you can usually recover them with a spark plug thread chaser.

For the RV8 you need the following tap (14mm X 1.25mm pitch).

[dog man]

Yes probably looks a bit misleading how I put it sorry. Main point I wanted to make for op's benefit though is they tend to be ''plug sockets'' rather than 21mm sockets but it's all the same thing isn't it! Although ''plug sockets'' will probably have the in built universal joint

[Chimpafrolic]

dog man said:

Yes probably looks a bit misleading how I put it sorry. Main point I wanted to make for op's benefit though is they tend to be ''plug sockets'' rather than 21mm sockets but it's all the same thing isn't it! Although ''plug sockets'' will probably have the in built universal joint

Totally agree Dogman, wast trying to show you up mate.

Even tool suppliers and manufacturers can make this confusing for the consumer, obviously what Chris needs here is a dedicated plug socket or spanner not just a 21mm socket.

A point worth making is I often find a new plug socket is difficult to remove once the new plug is in place.

This is because the rubber insert designed to hold the plug on the socket is a tad too tight when new.

A good tip is to dig out the rubber insert and put a small cut in the central hole with a razor blade before refitting it in the socket.

This saves the frustration of trying and encourage the socket off the newly fitted plug only to find you are left holding the 3/8" extension with the socket still stuck to the plug in the head.

Hope this helps?

[Chris71]

Just having a look at this stage! What do people make of these (forward most plug from each bank):



In the daylight there didn't look to be a huge amount of difference between the two, so I went for a close up of one of them:



Coincidentally, the air filter element is currently drying out next to the radiator! It seemed pretty clean to me. The only odd thing was it was an extremely tight fit to get out through the gap where the grill normally sits - is it possible mine's oversized (and hence perhaps the wrong type with the wrong flow characteristics) or are they normally a bit of a squeeze to remove?

[dog man]

Those plugs look pretty much spot on...perhaps a bit rich, did it get to warm up before they were removed, i.e did it come off choke?

[ralphy12345]

@ Chimpaholic:
thanks for the advice (in both post), really useful stuff.

R

[dog man]

...as for the electrode..well it's hard to tell but I did my plugs in accordance with the service schedule...44k is it? I forget. Anyway they were in really good shape but new ones went in anyway! When I used to work as a mechanic (10+ years ago now) plugs like that would sometimes just get cleaned up and refitted and charged as new plugs

[Chris71]

dog man said:

Those plugs look pretty much spot on...perhaps a bit rich, did it get to warm up before they were removed, i.e did it come off choke?

They were removed with the engine stone cold this afternoon (the last time it went out was a 15 minute run on Thursday evening where it may not even have got up to temperature).

I guess it's possible the remaining 6 cylinders are all incredibly rich if it's one injector per cylinder, but the condition of those tends to suggest it's not the lambda sensor or AFM I'd guess? That would presumably cause the ECU to overfuel all cylinders (or at least all on that bank).

The car often stands for 5+ days at a time, so I think I'd see a pool of petrol or at least smell it if there was a leak. What else can it be?

ETA, from a very old thread I found on a search:

FunkyGibbon said:

FourWheelDrift said:

I get around 14-16mpg with mine (5 litre).

same here (450)

Maybe it really is just too much town driving and cold weather.

Edited by Chris71 on Saturday 29th January 16:26

[Chimpafrolic]

dog man said:

Those plugs look pretty much spot on...perhaps a bit rich, did it get to warm up before they were removed, i.e did it come off choke?

+1

Although they do look a bit sooty if you look closely at the insulator tips on both plugs they look like the right colour to me.

You can also just see the nice grey/brown colour under the black on the electrode, so I would class your plug colour as perfectly normal Chris.

I am pleased to hear your air filter was not too dirty as it indicates the car has been properly looked after.

I actually had my money on you finding it really clogged up, shows you how much I know.

However if you PM me I have something that may help with your economy.

Dave.

[blitzracing]

Chris71 said:

Maybe it really is just too much town driving and cold weather.

Edited by Chris71 on Saturday 29th January 16:26

That may not be so far wrong, and the plugs may just be a result of cool running (The carbon burns off at higher temps so the plug electrode appears whiter.) I think you now need to try and get some stiff copper wire or like (try stripping out some of that grey flat mains cable used in house wiring) to get down the side of the lambda connectors now and check they are cycling on both sides.

[Chris71]

Chimpafrolic said:

I am pleased to hear your air filter was not too dirty as it indicates the car has been properly looked after.

Yep. The stepper motor was practically gleaming when I took that out recently, the oil's nice and clean and the plugs were torqued correctly, so I've relaxed a little after the Wanli tyres saga!

God knows how long the filter is going to take to dry out. Four and a half hours later it's still soggy to the touch...