Petrol engines aircooled spark plugs

From VW T25(T3)-Tech
Jump to navigationJump to search

kev the rev

Usual recommended plugs

Spark plugs Bosch W8CC

Electrode gap .6mm

W7CC (a colder running plug than W8CC) also recommended by other sources (see below)

Forum Discussion

81aircooled: LOng trip to Italy, 29 year old T25 with 2.0 CU aircooled engine. Anything else I need to be aware of before setting off?

Gunslinger: ....

... I'd replace the plugs (Bosch W8CC) and clean and regap (.6mm) the old ones to keep as spares.


paul66beetle: Aren't they W7CC's. I've worked from the following table for CU engine it specifies W7CC and for the Aircooled CT/CZ engines W8CC?

  • 2.0 litre CU/CJ/CV engine: Bosch W7CC or equivalent
  • 1.2,1.3,1.5,1.6 litre D/F/AB/AR/H/B/AS/AD/AJ etc: Bosch W8AC or equivalent
  • 1.6 litre CT/CZ engine: Bosch W8CC or equivalent
  • 1.6 litre ACD engine: Bosch W8DTC, Beru UX79 or equivalent

NB. The W7CC is usually gapped at 0.6mm (though depends on engine and ignition system of course - [HM])

Gunslinger: Just had this useful info from Tom Green at The Green Spark Plug Co. (and his prices seem reasonable)

Hi Stuart, The W8CC is the correct plug for your van. The W7CC is a colder plug which you would probably use if you were towing a caravan or similar.

paul66beetle: This sparkplug debate gets curiouser and curiouser :lol:

Just been into Euro Car Parts and they have pulled up W7CC for the T25, Just Kampers only sell the W7CC for the 2.0 CU engine. They sell the W8CC for T25's with the 1600CC engine. Looked on Brickwerks but they dont specify type in their shop.

My thinking is most of my travels will be long distance with a laden van, plus my poptop & the drag efficiency of a brick maybe the W7CC ones are the plug of choice. Probably most excursions will be in the summer albeit a British Summer!

Plugs - heat-range choice

The general rule for plugs is to use the hardest (coldest running) plug, that doesn't oil up or cause poor idling/misfiring - for the conditions of use.

That's the safest.

Idling doesn't matter for a race engine, once started warmed and under way its as cold as allows good pickup from slow sections - this would in the past involve starting on warmer plugs and then changing to a race plug - an extreme example.

For road use, typical load as well as ambient temperatures and engine condition determine what can be tolerated.

Poor cooling, hot intake air or retarded ingition all point to a softer plug overheating, and use of the harder choice

An engine in poor condition, with bad rings, valve seats and low compression can give more oiling, misfiring and idling problems with a harder (colder) plug.

In this case we have two choices which I imagine are quite close together...

In other words a good condition, high compression, clean running engine should easily tolerate the harder choice, and give more confidence in pushing on when everything gets a bit hot. If it's burning a bit of oil and is not spot on, the warmer plug might be the one.

Only you can know, if in fact it matters much, which in general obviously doesn't due to the two recommendations being fairly randomly made...


Other related parts

81Aircooled: Has anyone got a part number for the HT leads? I think it might be 998 031 021 but I'm not sure if they are for Beetle only.

Paul66beetle: Original Part No: 905QHT016 lInk to Just Kampers

HT Leads

These are available from brickwerks The lengths from ETOS are as follows:

Cylinder 3 380mm

Cylinder 1 580mm

Cylinder 4 280mm

cylinder 2 480mm