The Triumph Dolomite Club - Discussion Forum

Just found this on spark plugs. When I first got my dolomite, I struggled a little with mixture. Something like this would have been really useful. Hope it helps someone out there with an equivalent lack of knowledge on classic cars!

Great posting ! Its the sort of thing that needs to be made a "sticky" perhaps.
Tony.

That's a great find, and thanks for sharing, so useful.

Thanks very much guys! I definitely thought it was useful! Tony what do I do to get it stickied?! Do I contact someone in particular?

if the plugs have a slight pink shading or blue that could be a sign the of the head gasket on its way out. Not experienced it on any of my Dollies but did once on a Alfa Romeo

Hi. This is a new question for this post. Does any of the information change when lead-free gasoline is used?
Thanks. Walter

Ridgemeadows wrote: ↑Fri Mar 03, 2023 12:49 am Hi. This is a new question for this post. Does any of the information change when lead-free gasoline is used?
Thanks. Walter

No change in the effect from unleaded fuel, nor, as far as I can tell, from modern E5 or E10 ethanol added fuels. Though you may find that you will need to alter the heat range of the plugs you use to keep up with the hotter running modern fuels and maintain engine efficiency.

Question! Apart from Avgas which is for light aviation use and illegal in road cars, (and flippin' expensive!) can anyone still get leaded fuel?

Steve

Leaded gasoline is still available in Canada, but only in Chevron-brand gas. It is rated at 94 Octane which doesn't compare with the UK octane rating system.

Ridgemeadows wrote: ↑Wed Apr 05, 2023 4:07 am Leaded gasoline is still available in Canada, but only in Chevron-brand gas. It is rated at 94 Octane which doesn't compare with the UK octane rating system.

British petrol (gas) sold today (next week may be different) comes in only 2 basic types. The UK standard is called E10 and is unleaded fuel of approx 95 RON and which contains a maximum of 10% added ethanol.

The other and more expensive variety is now known as E5, formerly "Super Unleaded", an unleaded fuel of 97-99 RON rating (depending on brand) and containing no more than 5% ethanol


The RON rating currently used in the UK roughly corresponds to the old octane rating or around 3 star in the old british star rating, where 2 star was 91-2 octane, 3 star was around 95 octane, 4 star was 98 octane and the late lamented 5 star was 101 octane.

5 star was scheduled to be phased out over 5 years, starting in 1971. In fact, it disappeared from UK forecourts in a matter of weeks! 3 star was phased out somewhere in the late 70s as there was little demand for the "halfway house" grade, leaving only 2 star and 4 star available.

Things stayed that way, through the introduction of unleaded fuel in circa 1986, which became universal in 1988 and on until relatively recently when the first ethanol added fuel was introduced. At first the base fuel was 95 RON E5 and the "Super unleaded" was 97-99 RON and largely without ethanol (though pumps invariably described it as E5 as some counties added ethanol) A couple of years ago the system was updated (?????) again to the current ratings above.

If you have an OHV engined Dolomite In Canada, I would recommend you seek out and use the Chevron 94 octane leaded fuel as this will be kinder to your cast iron head. However the OHC "slant" engine with it's alloy head and steel valve seats is perfectly happy on unleaded fuel. If you have a slant, octane rating is more important than lead content, search out the highest octane unleaded fuel you can easily find, it'll be fine.

One last word of warning. If you are likely to have to use ethanol added fuels, even occasionally, it's best to get all your rubber fuel hoses replaced with ethanol proof material like Gates' "Barricade". Ethanol, even as little as 5%, literally dissolves ordinary rubber fuel pipes and can easily cause fires. I've seen it too often, even here in the UK where awareness of the problem is high!

Steve

I am using E5 petrol, and as mentioned above, it may need different range of plugs to the BN9Y recommended in the manual.
Which is the best spark plug for a standard Sprint with a stainless steel exhaust?

DickA wrote: ↑Fri May 23, 2025 5:29 pm I am using E5 petrol, and as mentioned above, it may need different range of plugs to the BN9Y recommended in the manual.
Which is the best spark plug for a standard Sprint with a stainless steel exhaust?

NGK BP6EFS

Thanks.
Dick