Replacement of Spark plugs and HT leads.

Whilst the spark plugs and high tension (HT) leads are designed for a reliable 5 year life, some including Roger Parker, advocate the more regular replacement of spark plugs for optimal performance, fuel efficiency and emissions. This is an easy job, so there is no reason why an eager DIYer shouldn't take on a spark plug replacement every 2 years/24000 miles. Here is how it is done.

Tools required.
  • 10 mm socket for removal of engine inspection cover.
  • Spark plug box spanner (pictured right, costs about 5 quid from Halfords, it is long enough to reach the spark plugs found deep in the cam cover of the engine and well worth the investment).
  • A large Phillips screw driver.

sparkwrench.jpg (3208 bytes)

Time required:

Spark Plug removal:

Before starting work, make sure that the engine is cold enough to work on.
1 Remove the engine inspection cover, to expose the engine as seen in panel A.
2 Remove the spark plug cover from the engine cam cover as shown in photo B - it is held on by two Philips-headed screws.
3 Remove the HT lead, one at a time for the individual spark plug you are about to replace. Whilst it is unlikely you could mix up the order of the HT leads with this ignition system design, this method reduces the likelihood of a cock-up even more! In photograph C one can make out the spark plug deep in the recess of the head.
4 Use the spark plug spanner and remove the spark plug.
5 Make sure that the new spark plug is correctly gapped (0.9 mm or 32 thousandth of an inch for the MGF - 1.0 mm on the later TF), and using the spark plug spanner install new spark plug into the engine.

 Ensure that the plug is adequately torqued (25Nm) in and replace HT lead.

 The lead should attach with a palpable 'snap'.

sparkers.jpg (48141 bytes)

HT lead removal:

Replacement of HT leads follows the same procedures as the spark plug instructions as above. Here are shown the 8 mm Magnecor ignition leads as retailed by Brown and Gammons. They are numbered, and are a direct swap for the original leads.

Mk1 MGF MPi leads run from a distributor mounted to the inlet cam (top right corner of picture, opposite). A further lead runs from the coil tucked under the inlet manifold.

Mk1 VVCs have twin coil ignition, and no distributer - and therefore VVC HT leads are not compatible with leads intended for the MPi.

Later, Mk2/MY2000 MGF and all TFs use MEMS3 engine management. On these engines there are twin coils but mounted in the cylinder head for both MPi and VVC variants. Unsurprisingly the leads are not interchangeable!

HTleads.jpg (18147 bytes)

Spark Plug FAQs

Frequently Asked Questions: MGF/TF Spark Plugs

A common question come service time is what spark plug to buy when replacement is due. The original fit spark plugs are long-life, 60k mile platinum tipped Champion RC8PYP or Unipart GSP 9652 (MG Rover/ X-Part part number NLP100290 or NLP100290P; Land Rover part number NLP100190) and these were fitted both to the multi-point injection (MPi) and variable valve control (VVC) engine variants of the 1.8 litre K-series. The smaller-capacity 1.6 also uses the same spark plug.

Do I have to use long-life spark plugs? In fact the answer here is no. Roger Parker has been an exponent of the use of cheaper copper-cored spark plugs but these will need more regular changes (perhaps every 20k miles). As our MGs get older, the annual mileage tends to drop, so the chances are a 20k mile spark plug will have a very long duration service life. There again, a platinum plug could last decades depending on the use you subject the car to!

Personally, because the cylinder head is made of relatively soft aluminium, I would suggest the use of a long-life plug so as to give the cylinder head an easier time: over-torquing the spark plug can lead to stripping of the thread and an unusable engine. This is not the end of the world fortunately: damaged cylinder heads can usually be recovered using a "Helicoil" but is a complication best avoided.

Do I have to use the originally specified Champion or Unipart brands? Again the answer is no. Equivalents are widely available from the likes of Bosch and NGK. For example, in the NGK range the single electrode NGK BKR6E, double electrode NGK BKR6EK and platinum tipped NGK PFR6N-11 are all listed as being suitable for the 16-valve K-series engine.

What is the correct electrode gap? For the Rover K-series, this gap should be 0.9 (MGF) or 1.0mm (MGTF), 0.05mm. I personally would check and confirm the gap out of the box even if they are sold "pre-gapped."

Possible alternative spark plugs for Champion RC8PYP:

  • Autolite APP3923
  • Beru 14 FR-7 DPU3
  • Beru 14FR-5DPUX
  • Beru 14FR-7KPUX
  • Beru 14F-6DPUR02
  • Beru 14F-7DPUR02
  • Beru 14FR-7DPU3
  • Bosch FR6DPP332X
  • Bosch F7DPP222T
  • Bosch FR6KPP332S
  • Bosch FR7DPP22U
  • Bosch FRDPP10
  • Bosch FR5DP
  • Bosch FR7DPP+
  • Bosch FR6DPP22U
  • Bosch +11
  • Bosch FR6DPP33X
  • Bosch FR7DPP33
  • Bosch F7DPER
  • Bosch FR7DPP10
  • Bosch FR5DP1X
  • Brisk DR14ZC
  • Daihatsu 9004851166000
  • Denso PK20R13
  • Denso IK20
  • Denso PK20TR11
  • Denso PK20PRP8
  • Denso PK20R11
  • Denso PK20PR-P8
  • Denso PK20R8
  • Denso VK20
  • Denso K20TT
  • Denso PK20PTRS9
  • Eyquem RFC58LZDP
  • Fiat 60569957
  • Mitsubishi MS851346
  • Motorcraft AGPS22PP1
  • Motorcraft AGPS22P1
  • Motorcraft AGPR12PP8
  • NGK PFR6T-10G
  • NGK PFR6B-11
  • NGK PFR6U-11G
  • NGK PFR6G-11
  • NGK PFR6J-11
  • NGK BKR6EP-11
  • NGK PFR7G-9
  • NGK PFR6B-11C
  • NGK PFR6G-9
  • NGK PFR7G-11
  • NGK PFR6N-11
  • NGK PFR6J11
  • NGK BKR6EP-8
  • NGK stk 2743
  • Unipart GSP2055
  • Unipart GSP9652
  • Volkswagen VW 101000063AA
  • Volkswagen VW 101.905.611
  • Volvo 9179100
  • Volvo 917910

    Analogous \ Similar Parts of UNIPART GSP9652




    BOSCH 0 242 236 544 Spark Plug
    CHAMPION OE136/R04 Spark Plug
    CHAMPION OE136/T10 Spark Plug
    DENSO PK20PR-P8 Spark Plug


    ROVER NLP 1001 90 (NLP100190) Analogous / Similar Parts




    BOSCH 0 242 236 544 Spark Plug
    CHAMPION OE136/R04 Spark Plug
    CHAMPION OE136/T10 Spark Plug
    CHAMPION OE136/U04 Spark Plug
    DENSO K20PR-U11 Spark Plug
    LAND ROVER NLP100190 Spark Plug

    Manufacturer NGK

    Number 3546

    Description Spark Plug

    Spanner Size 16,0 mm

    Outer Thread [mm] 14,0

    Thread Length [mm] 19

    Spark Position [mm] 3,5

    Spark Plug 1 - Earthed Electrode

    Spark Plug Fixed SAE connector

    Spark Plug Nickel Middle Electrode

    Spark Plug With gasket seat

    Spark Plug interference Suppression 5 kOhm

    Assembly Ignition System

    Cross numbers KIA 0K55818110

    MG NLP100290

    ROVER NLP100290

    HT lead part numbers:

    Set-high tension lead ignition - Genuine MG Rover

    1800cc - K Series


    Set-High Tension Lead Ignition   

    1800cc - K Series


    Lumenition Silicone Blue BLS535 Ignition Lead Set 

    1800cc - K Series


    Lumenition Silicone Blue BLS535/BLC535A Ignition Lead Set with Coil Lead 

    1800cc - K Series


    Lumenition Silicone Blue BLC535A Ignition Coil Lead 

    1800cc - K Series