Petrol for Vintage Car

[l5foye]

I am about to put a 1930's Austin on the road. I'm told that I need to put an additive in the petrol. However
unleaded petrol was not introduced in the UK until the late 1960's.The car would have been run on unleaded petrol was over 30 years, so my question is -why would it be necessary to put in an additive now? Am I missing something?

 

[daveenty]

Leaded petrol was still available until c2000, though most people had either had the valve seats hardened by then or were using an additive in the fuel.

Have a look HERE for some information on fuel additives.

 

[grober]

Tetra ethyl lead was used as an anti-knock additive to prevent pre-ignition as higher compression engines demanded higher octane fuel. It had the added advantage of lubricating the valve seats reducing wear/erosion. Relapping worn valve seats was a fairly constant process on pre WW2 engines to maintain any compression so an additive with anti wear characteristics might not be a bad idea even if not required from an octane enhancer point of view?

 

[Swotty]

Contact the owners' club - don't second-guess. Also contact previous owners, if you have their details.

Do you know if the engine has ever been modified to accept modern fuels? Probably not for the age of your car. Short of stripping it, best to ask.

Classic car ownership can be so rewarding and yet, at times, so frustrating! My oldest car is a '54 Sunbeam Talbot 90. Unmodified, it needs an additive. My 1965 Wolseley 6/110, with only 45,000 miles, had an engine rebuild in 2003 in Holland. The seller told me it needed an additive. When I checked with the garage in Holland (thank God they all speak English over there!), they confirmed it had hardened valve seats, so will run happily on unleaded.

I would start with the owners' club.

Good luck,

Stuart

 

[190]

The potential issue is valve seat recession on the exhaust valve. Without the lead to lubricate the valve seat, micro welding takes places between the valve face and seat stripping off material. That's the theory but if this happens at all it will be at sustained high revs when the valve and seat are at the highest temperature. My practical experience is with a 79 BMW motorcycle which has cast iron valve seats. Over my 12 years of ownership I have never used a proprietary additive and I've not experienced any measurable valve set recession. Basically if you notice the valve clearances closing up between services then that's an indicator of valve seat recession. For me the whole issue was way overblown when unleaded fuel was introduced. Yes it can happen but it's not inevitable on a moderately driven vehicle. Of course the manufacturers of expensive additives will have you believe otherwise.

 

[markjay]

I am about to put a 1930's Austin on the road. I'm told that I need to put an additive in the petrol. However
unleaded petrol was not introduced in the UK until the late 1960's.The car would have been run on unleaded petrol was over 30 years, so my question is -why would it be necessary to put in an additive now? Am I missing something?

I am not sure when exactly lead in petrol became common in the UK, but the benefits of adding
Tetraethyl lead to gasoline were first demonstrated in the US in 1921, so presumably your 1930's Austin engine drank leaded petrol for most if not all of it's service life?

 

[grober]

According to
Lord Montagu of Beaulieu in the House of Lords in Hansard in 1998

The search for a miracle ingredient had been instigated 15 years earlier by Charles Kettering, the engineering genius of General Motors and a research chemist named Midgley, after reputedly trying 33,000 different chemical compounds. The result was tetra-ethyl lead. It was first brought to Britain in 1928 under the trade name "Ethyl" by Pratts Petroleum, the ancestor of modern Esso. Ethyl also enabled the development of the new generation of aero engines which gave this country the Schneider Trophy victory and the Battle of Britain. For decades it was the essential diet of all good car engines.

this lead me to this rather interesting discussion on aviation fuel ratings used by piston engined aircraft in WW2
High Octane fuel in Britain WW2 | Forums

 

[grober]

Getting back on topic- exactly which 1930's Austin model are we talking about?

 

[l5foye]

It is an Austin 10 Cambridge. I checked with the Club and opinions seem to be divided as to whether an additive is necessary or not.

 

[ioweddie]

Surely it won't hurt to add it anyway, better safe than sorry

 

[grober]

ROAD TEST - AUSTIN 10/4 CAMBRIDGE | Classics World

1125cc sidevalve engine - cast iron block alloy head?
here's a video for those unfamiliar with side valve engines.

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and here's the basics of lapping in a valve [ albeit on a smaller engine]

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[WOODYTHEWISE]

Thanks ever so much for posting that.
I bet people in the past have had tool kits including the valve stick with rubber and wondered what the he'll it was for. Now they know.

 

[markjay]

...
I bet people in the past have had tool kits including the valve stick with rubber and wondered what the he'll it was for. Now they know.

Oy! I used this... with fine grinding paste... slow manual process... it wasn't that long ago

 

[markjay]

3:10

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[WOODYTHEWISE]

I know...been there...done that. Hand lapped large water and live steam valves, then used gland packing and tallow to seel .
Those were the days my friend....

 

[grober]

The PERMATEX Valve Grinding Compound is Silicon Carbide in a gell carrier.
Silicon carbide was discovered by the American inventor Edward G. Acheson in 1891
Silicon carbide | chemical compound

 

[brucemillar]

I know...been there...done that. Hand lapped large water and live steam valves, then used gland packing and tallow to seel .
Those were the days my friend....

I love those double ended dual coarseness pots of lapping paste. I did used to cheat (no surprises there) and have a lapping tool on my leccy drill. Still a boring job to do. But well worth the finished results when doe properly.

 

[219]

I am about to put a 1930's Austin on the road. I'm told that I need to put an additive in the petrol. However
unleaded petrol was not introduced in the UK until the late 1960's.The car would have been run on unleaded petrol was over 30 years, so my question is -why would it be necessary to put in an additive now? Am I missing something?

I thought the addition of tetra ethyl lead only came in post war and that all vintage and earlier cars would have originally ran on unleaded equivalent of two star anyway ?

 

[Benzowner]

Have a google at "New valve seats cost" There are a number of companies there who will refurb your head for about £100 or so. Did the same on my 1966 mini 850 many years ago. By far the best solution, adds value to your car and no more additives.

If you run the engine on unleaded, you will burn out the valve seats.

 

[grober]

this AUSTRALIAN FORUM may be of interest?
Leaded or Unleaded Fuel for 1932 Austin 10 (Page 1) / Public Requests For Club Assistance / Austin Ten Drivers Club
quote :-
The introduction of lead in petrol in the 1930s raised the octane rating. Top grade was 80 octane. Standard grade was 75 Octane. Post war pool petrol was even lower http://hansard.millbanksystems.com/comm … l-standard

Austin Ten's are side-valve low compression and will run on the lowest octane you are likely to find today. 91 is fine.

Your lead replacement additive will help reduce valve recession and lengthen the periods the between de-cokes & valve grinding (2000 miles & 4000 miles in your '32 handbook). FBHVC has tested and recommended most of the available brands http://www.fbhvc.co.uk/legislation-and- … formation/

If fuel in Australia now has ethanol added you may need to use another additive to counter that.

FOLLOW UP THAT SECOND LINK FOR ADDITIVES
Fuel Information

ps As with all fuel additives which are in more concentrated form until diluted with fuel, care should be exercised in handling/ dispensing them.