Fuel octain ratings and mirrors !

[David FaulknerParticipant]

 Bernie Shaw wrote: I can confirm the “Car Builder Solution” mirrors have been out of stock for about 12 months.

Thanks for the update on the mirrors Bernie as some prices from other sources can be extortionate

[David SelfridgeParticipant]

Hi Rod & David

Attached a photo of the mirrors that I fitted, Well pleased with quality of the product and the very Good Chrome.

Regards Davy 

 

 

 

 

 

 

[David FaulknerParticipant]

I’m reviving this thread following recent issues with my Traction. Basically I had an exhaust valve on No3 cylinder burn out even though the head has hardened valve seats. The car has been run for around 12,000 miles on a mix of 95 ron unleaded and 98 Ron Premium unleaded and with a ‘Spitfire’ additive in the tank.

Reading back through floating power unleaded use has cropped up several times over the years and it appears that professional advice is that using Premium grade fuel makes no difference.

Volume 14 1998 issue 01-2 June/July has an in depth article, part of which is worth repeating:

Fuel History: Before World War 2, leaded fuel was unknown. The maximum octane rating was about 92 but normal petrol had around 70. After the war, octane rating rose to 75 for normal petrol in 1956. At the end of the forties, lead was added.

Traction engine development: The first 70/s had a compression ratio of5. 7:1. Later, with the increase of piston displacement, the compression ratio also rose to 5.9:1 and then to 6.2: 1. The first 11 OJ shad a compression ratio of 5.9: 1, increasing to 6.2:1 with the introduction of the ‘Perfo’ engines. From 1950 until May 1955 it was at 6.5: 1. The 11 D engine had, from 1955 to the end of production, a compression ratio of 6.8: 1. The 15/6 had a ratio of 6.2: 1 until 1949, and later 6.5:1 until the end of production.

Lead additives in petrol not only avoid ‘knocking’ but also decreases the valve seat wear. In addition, the lead helps to improve heat transfer. In the case of leaded petrol, the closing valves ‘beat’ onto a relatively soft, damping layer which is not built-up with un-leaded fuel.

The valve clearances thus decrease more rapidly, and burnt valves can be the consequence of neglecting regularly to check the valve clearances. Until the end of the forties, petrol was unleaded and cylinder head reconditioning was practised every 20,000 to 50,000 km and was considered to be a regular repair.

Volume 14 1998 issue 3 July has an item from FBHVC has a further item basically confirming the 1st article but leaning towards ‘additives’ available only being partially effective

Finally Volume 15 1999 issue 2 May has a further article that concludes that cast iron engines were more at risk from unleaded fuel and that whilst wear rates were unpredictable  and could vary widely in a 4 cylinder configuration No 3 cylinder frequently displayed the highest rate of exhaust valve seat recession which mirrors my personal experience.

The above are selected parts of the articles listed and it is worth reading them fully.

I’m personally guilty of not checking valve clearances since the engine rebuild in 2013 which has proved an expensive error and wish I had read those articles earlier, so will now make valve clearance checks part of my annual routine maintenance.

[Phillip RogersParticipant]

Hi, does anyone have a new email address for Mike Bigland, I am after a set of his mirror Brackets if he still makes them,

tried the email address listed on page 1 and the email bounced back.

regards

Phillip

[BernieParticipant]

Philip,

I have left Mike a voicemail message asking him to check the Forum because you want a pair of his brackets but cannot get through on e-mail.

B……………….

[Phillip RogersParticipant]

Thanks Bernie,

appreciated

Phillip

[Editor FPParticipant]

If you haven’t had an unleaded conversion, then the FBHVC recommendation is an additive.

They endorse Millers VSP Plus, Redline lead substitute and Castrol Valvemaster/ Plus

Engines that are used constantly at the top end of their rev range are probably more likely to be vulnerable to recession than those used in a more leisurely fashion. For this reason I try to avoid long motorway thrashes.

Personally, I wouldn’t dangle fuel additive balls in my fuel tank, even if they were deemed good enough for Rolls Royce Merlin engines.

[Martin de LittleParticipant]

On the matter of the Spitfire Fuel Tin Amalgam pellets etc ….Nope  – a complete waste of time (and indeed anyone’s money)  with no  empirical  or scientific  basis whatsoever.   Roughly on the same level as the  “Find the Lady”  (or 3x card) trick or the extravagant  claims traditionally made for Snake Oil.

Since when did tin  ever dissolve in petrol? My Normale tank has been soldered together and still seems to be holding after 67 years .The  various claims that it replaces lead tera ethyl, it reduces pinking,  it prevents valves from burning out  it has some kind of catalytic properties are yet to be proven.

The entry level  Castrol Lead additive is the stuff you want. If you hunt around there is a version that adds  to the octane  rating of your fuel and there is one that does not. As your engine is all of a magnificent 6:1 compression ratio, trying to improve performance through spending on raising octane levels is  not going to make much or any difference.

Meanwhile only put in   non E numbered fuel. Typically this will NOT be 95E but Super at 98 (yes i know it costs more) . The E stands for Ethanol and that will be bad for any aged motor car for quite a few reasons.  One is the damage it does to non ferrous metals (pipeline, pump and  your carb, and it is said oil seals ) and 2) it absorbs water that then sits around in your tank and fuel system.

Perchance you are going to France  you may find that there is no fuel  available that is E free. Typical fare is E5 – 95 and E10 – 98. In that case you can buy from Millers  (at an eye watering price i am afraid)  an additive that does both valve protection AND negates the damaging effects of Ethanol.

If you still  think that Spitfire stuff is value for money,  I can sell you some shares in the Brooklyn Bridge.

Cheers

MdeL

 

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