Tuesday, 25 September 2012

Typical 1940’s racing fuel components

The following technical information is dated 16th May 1946 and is provided in Jimmie Simpson's  little black book.

Specific gravity @ 60°F
Boiling Range
Chemically correct mixture air /fuel by weight
Latent Heat, B.Th.U.S/Lb
Latent heat per pound of air in a chemically correct mixture (see note 2) B.Th.U.S
Lower calorific value B.Th.U.S/Gall
Petrol (aviation) base stock
50-150°C (50% below 100°C)
Benzole (high quality)
78-120°C (90% below 100°C)
Methyl alcohol (Methanol)
Ethyl alcohol (Ethanol)

Petrol (aviation base stock) - Petrols vary widely in boiling range and anti-knock value. Octane number if typical aviation stock is about 75.

Benzole (high quality) – Benzoles subject to variation. Anti-knock value indeterminate (see note 3)

Methyl Alcohol (Methanol) - Anti-knock value indeterminate (see note 3)

Ethyl Alcohol (Ethanol) - Anti-knock value indeterminate (see note 3)

Acetone – Anti-knock value about 100 Octane

Ether – Very poor anti-knock value. Can only be used sparingly. Used to improve volatility.

Water – Used with alcohol fuels to increase the latent heat still further


1)      The question of solubility of one component in another is rarely an involved one. Although it requires careful consideration it is not normally a serious difficulty

2)      In tables such as this, it is usual to give the latent heat of the fuel alone. However, it is considered that the latent heat per lb of air in a “correct” mixture is more significant in practice

3)      The anti-knock values of benzole, methanol and ethanol are normally quoted as being 90-100 Octane. In most racing motor-cycle and car engines, however, the effective anti-knock values of these fuels are very much higher indeed.

Monday, 24 September 2012

Blending Fuels – the 1950’s way

I thought this blog post would give an insight to the method used for blending racing fuels in the 1940/50’s. The guidelines for fuel blending come from Jimmie Simpson’s notebook  (Jimmie Simpson Blog post)used when he was competitions manager of Shell-Mex and B.P. Ltd.

The blending process:

1)      Inspect the 50-gln. Barrels to see that they are thoroughly clean and unlined – for this inspection a special inspection lamp is being sent to the depot.

2)      Clean all equipment that is to be used (measures, funnels etc) by washing with spirit or benzol (dependent on the type of fuel being blended).

3)      Calculate the quantity of components required and stack the cans in separate piles near the blending barrels.

4)      Take a sample of each ingredient from the bottom of the packages by using the valinche and test the specific gravity (see table for specific gravities)  

5)      Calculate the specific gravity of the resultant mixture arithmetically (see example)

6)      Calculate the best means of having complete blends in each of the barrels at your disposal (i.e. halve the components and place half in barrel 1 and half in barrel 2, when blending operations commence).

7)      Start blending by filling into the barrels the ingredients having the lowest specific gravity. Then add alcohol and benzol alternatively. These latter components, having a greater gravity will fall to the bottom of the barrels, whilst the lighter spirit will tend to rise, and in so will mix to a certain extent with the other ingredients. As cans are emptied, stack on one side and leave until the blend is completed, mixed and sampled. Any error in the resultant specific gravity can then be checked against the actual components used. When figures are agreed, remove the empty packages and commence canning of the blend.

8)      Use either a 2-gln. or a 5-gln. measure each time to ensure that the correct quantity has been used. (Do not pour straight from the cans, as it is impossible to say whether they contain the exact tow gallons.)

9)      In adding the dye, care should be taken that it is added a little bit at a time, during the actual blending, to ensure complete mixing.

10)   If it is necessary to add Castor Oil to the mixture, then the oil should be mixed thoroughly with part of the Methanol and/or Ethanol, and added to the blend; vigorous stirring should accompany this process. A milky, frothy mixture will result when the Castor Oil is added to the mixture, but this will disappear when the mixture is assed to the bulk blend. The resultant fuel, however, will not have the same crystal clear appearance as a fuel with no oil addition.

11)   If, on the other hand, it is necessary to add a mineral oil to the mixture, e.g. Triple Shell (Heavy), the same process should be carried out, but the oil should be mixed with the benzol or petrol (preferably the benzol) and not to the alcohol.

12)   When the blend is finished, replace the bung and roll the barrels for a short while to ensure that the components are thoroughly mixed – alternatively stir the mixture with a clean, un-painted wooden or metal dip-stick during blending, which will reduce the rolling period required to a minimum.

13)   Replace the barrel on the stollard and by using the valinche take a sample from the bottom of the barrel and check for appearance and take the specific gravity. This latter should be the same as was calculated in (5) by calculation, but if there is a discrepancy check through all the process and make sure that the correct quantities have been added: also check your calculations.

14)   When the gravity is agreed, canning operations may be started (each can should be carefully examined beforehand to see that it is perfectly clean).

15)   When all filling is finished, carefully clean and dry the hydrometers and keep an exact record of the blend made in a special book, together with dates, quantities of ingredients, etc.

16)   If at any time it is necessary to blend a special mixture for anybody, full details are to be kept, together with the person’s name and performance of the fuel in the engine concerned.

Specific Gravities @ 60°F

Methanol                            .796

Ethanol/Benzol                 .820/.825

Ethanol/224                        .783

Ethanol/Shell                     .783

DTD 224                                .736

Shell                                      .736

Benzol                                  .860/.870

T.T. Benzol                          .873

Swan                                     .685

Acetone                               .796

Water                                   1.000

Shell Castor Oil G              .950


Specific Gravity Correction factors per every 1°F are:-

Petroleum Spirit of Specific gravity           .675/.714                             0.0005

do. do.                                                                  .715/.750                             0.00045

do. do.                                                                  .751/.800                             0.0004

Alcohol                                                                 .780/.820                             .0005

Benzol                                                                  .860/.880                             .0006


Spirit of specific gravity .730 @60°F – to calculate its specific gravity @ 50°F :-

Temperature difference = 60-50 = 10°F

Correction factor - .00045 per 1°F

0.000045 x 10 for 10°F = 0.0045

As temperature is lower than 60°F, add factor to specific gravity @ 60°F: .730 + .0045

= .7345 – Specific Gravity at 50°F


Spirit of specific gravity .730 @60°F – to calculate its specific gravity @ 70°F :-

Temperature difference = 70-60 = 10°F

Correction factor - .00045 per 1°F

0.000045 x 10 for 10°F = 0.0045

As temperature is lower than 60°F, subtract factor to specific gravity @ 60°F: .730 - .0045

= .7255 – Specific Gravity at 70°F


Method of calculating specific gravities:-

Note:    For the purposes of these examples gravities are quoted at 60°F. It should be remembered that should the temperature be below 60°F the component will have a higher specific grvity and if above 60°F, the component will have a lower specific gravity.


Specification:                     %                            S.G.

Methanol                            80x                         .796                        63680

Benzol                                  10x                         .862                        8620

Acetone                               10x                         .796                        7360


Specific gravity of resultant mixture is .7966 by calculation


Specification:                     %                            S.G.

Ethanol                                 70x                         .820                        57400

Benzol                                  20x                         .860                        17200

Shell                                      10x                         .736                        7360


Specific gravity of resultant mixture is .8196 by calculation

 BP Racing Ethyl

Specification:                     %                            S.G.

Methanol                            97x                         .796                        77212

Acetone                               3x                           .796                        2388


Specific gravity of resultant mixture is .796 by calculation


Dye addition = ½ pint Master Dye Solution per 100 gallons

=284 ccs. Master Dye Solution per 100 gallons.

=10 fluid ozs. Master Dye solution per 100 gallons.

Dye addition per gallon = 2.84 ccs. Master Dye Solution per 1 gallon – say 3ccs Master Dye Solution per 1 gallon.

Monday, 30 July 2012

Jimmie Simpson – motorcycle racer and Shell-Mex & B.P. Ltd racing manager

This is the first of a few posts I will do which relate to Jimmie Simpson.

Jimmie is best known for his motorcycle racing exploits. He was the first man to lap the IOM at 60, 70 and then 80 mph. In recognition of these feats the Jimmie Simpson is awarded annually at the TT for the rider who posted the fastest lap of the week.

Jimmie’s first TT was on a Scott in 1922, but from 1923-28 he raced for AJS. From 1929 he joined the Norton team.  Even with many wins all over Europe and the lap records at the IOM, a TT win eluded him. Jimmie’s final year racing was 1934. In the winter of 1933 Jimmie became racing manager for Shell-Mex and B.P. Ltd. Shell-Mex still allowed Jimmie to do one more year of racing. At the 1934 TT Jimmie had his best ever with two second places in the Senior and Junior and a long overdue victory in the Lightweight on a 250cc Rudge.
Jimmie Simpson

Throughout his racing career Jimmie was European champion 5 times (350cc in 1924, 1927, 1933 and 1934, and 500cc in 1926), as well as winning many important races.

His contribution to racing is better documented elsewhere, but the blog posts I will do on Jimmie is based on his role as racing manager for Shell-Mex & B.P. Ltd. Jimmie stayed with Shell for the rest of his working life and in his role was involved in many important aspects of both motor car and motorcycle racing. It is through Jimmie’s notebook from his time as Shell-Mex racing manager that I hope to give an insight into the role of a competitions manager of a major oil company.
Jimmie Simpson's notebook from his time as Shell-Mex & B.P. Ltd. racing manager

Tuesday, 19 June 2012

Valves for the Hopper special

I thought I would do a little blog post about the latest work that has been done on the Hopper special’s Lea Francis engine.

It is not often when you get original correspondence from the engine builder about how he built his engine. In this case we were very lucky when it came to the Hopper special valves.

Below is a picture of a standard Lea Francis valve which is suitable for the 1500cc Dirt Track engine.

Std Lea Francis valve

The next couple of photos show a letter and drawing from Ian Hopper about how he wanted to modify the valves for the Hopper special.
Letter from Ian Hopper

Drawing showing modifications to the inlet valve

Given Ian wanted to build his engine this way, it was only right to remove all the valves and machine them as he intended. The photo below shows the newly machined valves to Hopper specification as well as some of Ian’s old valves.
New valves modified to Hopper's specification along with some of the original valves

The final scan is of Ian Hopper in his mk3 Hopper special and is from an advert in this years’ Classic Monte Carlo rally programme.
A picture of Ian Hopper in his mk3 Hopper special at the Rest and be Thankful

Monday, 11 June 2012

Biscuits and Motorcyclist from Glasgow

I know it is a strange sounding title for this blog post, but if we go back to the 1950-60’s to the outskirts of Glasgow, we find a link between the two.

As you may have seen in some of my other Blog posts, Joe Potts ran a very successful motorcycle racing team from Bellshill. Joe’s business interest went further than bikes, as he also ran a successful garage, filling station and funeral parlour. Joe was well liked by all who worked for him and was known for looking after his staff.

One such way Joe looked after his staff was to give each of them a hamper at Christmas. This is where the biscuits link comes in.

Tunnocks which are based round the corner from Bellshill in Uddingston have been a family bakers since 1890. It was in the 1950’s that Tunnocks expanded and started to produce the products they are now famous for, for example the caramel wafer bar, teacakes, snowballs etc.

So when it came to Christmas, Joe made sure that the hampers for his employees were filled with Tunnocks products.

This isn’t where the link ended. During the 1950’s, motorcycling clubs were very important in Scotland, and one of the most famous from the area was the Avon Valley club. At club nights it would be common to have special events. One of the most influential members of the Avon Valley club was Charlie Bruce, who spent much time with the racing team at Bellshill. Charlie had arranged the likes of Bob McIntyre to speak on club nights.

On one occasion the Tunnocks link was again utilised, as a tour of the Tunnocks factory was arranged for the members of the Avon Valley club to go on a tour of the factory.

Tunnocks themselves have been involved in racing. For example, Boyd Tunnock who runs the company competed at the Bo’ness hill climb in 1962.

So when I was in Bellshill this last week I had to take the opportunity to visit the Tunnocks factory - and what a wonderful factory it is! The reception area is beautifully laid out with wonderful paraphernalia relating to the history of Tunnocks.

I am very pleased to say that Tunnocks are very happy with their association with the local business which was run Joe Potts. With this in mind Tunnocks were happy to donate some caramel wafer bars to the Joe Potts collection of racing bikes/cars. These caramel wafer bars will be available to members of the public who visit the Joe Potts stand at the Bo’ness revival hill climb in September. Be warned, they will be given out on a first come first serve basis, and given how tasty they are, I can’t see them lasting long!

Wednesday, 9 May 2012

OHC Velocette – it could only be in a shed in Yorkshire

I was ferreting around West Yorkshire, when I ended up next to the Emley Moor radio mast. When I see that mast it means only one thing, I must go and call on an old friend who is in the vicinity.

When I think of Velocette ‘Specials’, bikes made in Yorkshire spring to mind. When you think of Yorkshire Velocettes, the name Swallow also springs to mind. If you combine Yorkshire, Velocettes and Swallows you end up with some interesting machines indeed.
Alec's badge of honour

The Swallow name is synonymous with Velocette, due to Ken Swallow being a Velocette dealer for many years in Station Road, Golcar. It was one of Ken’s son’s Alec that I went to visit.

As the van was parked on the main Kirkburton road, I immediately heard a single cylinder fire into life. Knowing this could only be Alec, I had to run to his house before he disappeared off on something tasty.

It was indeed Alec who had just finished sorting a Velo for a customer of his and was about to ride off to Leeds to deliver it. Seeing as we had called, Alec was quite happy to delay the trip so we could spend half an hour or so in the shed.
The Velo Alec had just finished rebuilding for a customer

If you asked Alec how he spends his time, he would probably say “pottering”. Now if Alec’s time is spent pottering, it is the sort of pottering I approve of!

Every time I visit Alec he seems to have been up to something new. Alec ‘s engineering work is not in the style of many – i.e. open up the cheque book and pay for a collection of parts. Alec is a man after my own heart – he enjoys building specials, and he does it himself. After all this is Yorkshire.

It was only a quick trip to see Alec, so I only got chance for a brief natter and to take a few photos of what he’s been up to. To quote Alec, “it’s not one for the purists” – and that is what makes it far more interesting!
Always something exciting to see - Alec's new SOHC Velo

The basis for the engine is a trusty Venom, but it is fair to say it looks a little different. When you consider that Alec has re-vamped the valve train and converted the engine to a SOHC setup, it is quite remarkable that the engine still looks so similar to a standard Venom. It is a neat setup that Alec has come up with and is pleasing on the eye. The camshaft is driven by a chain running from the original cam gear in the timing case, which still provides the required 2:1 reduction. This means that an equal number of teeth can be used on the drive sprockets, which in turn allows the chain-wheel in the head to be of a small diameter. This makes for a light and attractive looking top-end.  You might notice that ‘mk3’ is stamped on the cam chain cover – and for good reason. Alec has built two over-head-cam Venoms before – one a DOHC and one a SOHC.

 You see what I mean about Alec liking to do things himself?

 These earlier machines were built during Alec’s racing days in the 1960/70’s. It was not just special engines that were made during this period, as he also built his own frames (including a spine frame for a Velo based upon the Loch Ness monster) and built his own fibreglass fairings, tanks etc.

It is not just this new mk3 SOHC Venom engine that Alec has been working on. He has fitted the engine in a standard Velocette frame, which he has had to modify to accommodate. I was really impressed to see that Alec had made all the moulds and then done the fibreglass work for the tank, seat and oil tank on this bike. You will also see the interesting brake on the front of the machine. This is another leftover from Alec’s racing days, which uses a hydraulic conversion brake plate in a Norton hub.
A very neat looking machine
Alec's very nice hydraulic brake conversion

So that was my short trip to see one of the characters of the Yorkshire Velocette Mafia. It was only a fleeting visit to Alec’s so I have only kept this post short. But next time I am up I will go into a few other Velo specials that Alec has made over the years.
Alec even made the tanks, seat and mudguard for his new special

Sunday, 26 February 2012

Barton Motors - the Sparton, the Phoenix and more

In the late 1970’s some of the most powerful racing motorcycles were built in an isolated chapel in Caernarvonshire. From the Nazareth chapel in Pontrug , Barton Motors produced some very interesting large capacity two-stroke racing motorcycles.
Nazareth Chapel Pontrug

Barton Motors was started by Barry Hart and Tony Ryan. The Barton name is derived from the first name of the two company founders. Barry and Tony started the company by investing £15 each, in order to set up a barn with two lathes. Early business concentrated on producing racing gearboxes for Japanese bikes, then went on to clutches, cylinder barrels and heads.
Graham Dyson, Marilyn and Barry Hart and the Phoenix

One of Barton’s first breaks was when they were approached by Rex White of Suzuki GB. Rex wanted a 350cc Suzuki for Barry Sheene to race, and enquired with Barton whether they could do something with the Suzuki GT380. What Barton came up with was a water-cooled engine which still utilised the GT380 crankcases and crank. At a practice session at Brands Hatch, Barry Sheene was able to lap inside the existing lap record. However, the Barton 350cc was never raced. The official line was that Suzuki Japan heard of the 350cc, and put a stop to it as Sheene was contracted to race in the 500 and 750cc classes only.  In reality the Barton 350cc although promising, needed further development.
Sparton 500cc engine

The 350cc three cylinder became the ancestor of the 500cc Sparton motorcycle. The Sparton name comes from Barton engine coupled to a Spondon rolling chassis. During the development of the Sparton, Tony Ryan left the business as he was less interested in motorcycles. Barry Hart and his wife Marilyn moved from Surrey to Caernarvon with the business. Graham Dyson (now of Nova transmissions) joined Barton Motors soon after they moved to the chapel at Pontrug.
Sparton cylinder heads

It was 1974 when the 350cc three cylinder Sparton was starting to get off the ground. The engine had a 52 x 54mm bore and stroke, and utilised a Suzuki bottom end with special gear ratios. The initial 350cc Sparton was a little heavy compared to a Yamaha twin, so for 1975 a special lightweight unit with magnesium cylinder block and chromed aluminium liners was produced. Due to the chromed bore, Barton Motors spent much of 1975 waiting for the special piston rings which were necessary. Barry Hart therefore decided to concentrate on the 500cc class. The 350cc Sparton was sold to Monster Car Hire at Thames Ditton for Peter Dalby to ride.
Sparton 500

The initial Sparton 500s were actually 458cc engines using Omega pistons with a bore and stroke of 60 x 54mm. The Suzuki GT380 crankcases still formed the basis of the engine. The standard Suzuki is a 120 degree triple with six main bearings, geared primary drive and a six speed gearbox. The cylinders on the standard Suzuki are quite widely spaced apart to allow good airflow around the barrels. This made it easy to make space for water jackets for the water-cooled Sparton. One of the most obvious differences between the Sparton and standard Suzuki, is the use of a gear driven water pump on the drive side of the Barton and the Krober electronic ignition which is driven directly from the other side of the crankshaft. Inside the crankcases there were further differences, for example an extra bearing was added on the Sparton due to the   small supporting area on the timing side of the crankshaft.

The 460cc Sparton produced 95bhp compared to the standard Suzuki GT380’s 37bhp. A special 525cc Sparton which used Yamaha pistons produced 100bhp. The 500 Sparton shot to prominence at the 1975 TT when Martin Sharpe reached 146mph at the speed trap – fastest in its class jointly with the Works Kawasakis. In 1976 things got better for the Sparton with a 1-2 victory For Martin Sharpe followed by Big Frank Kennedy at the North West 200.

Graham Wood raced the latest version of the Sparton, which utilised a short-stroke 497cc engine to produce an estimated 105-110bhp. This Sparton was capable if over 160mph. In 1977 Graham Wood scored 12 firsts as a privateer on the Sparton 500. The Sparton engine cost £1300 on exchange (£1450 complete) whereas a Suzuki RG500 would cost more than double. Reliability of the engine was always an issue due to the use of Suzuki 380cc crankcases. A Sparton 500 engine weighed 92lb complete, which was 30lb lighter than an RG500 unit. However, due to the cycle parts utilised the Sparton actually weighed more as a complete machine than the Suzuki.

Barton Motors didn’t just make their own engines. They also modified many types of racing engines. Barton Motors offered mods to private owners for the Suzuki GT 750 which had established itself in F750 racing. Barton Motors offered four different stages of tune which resulted in the engine producing up to 115bhp. The conversion was extensive and included, keying the crankshaft tp prevent twisting, the insertion of spacers on the crank in place of oil thrower plates so that petroil could reach the main bearings, while big-end bearings were made fully floating to prevent seizure. A dry clutch mates the engine to a six speed gearbox and ignition is by Krober or the cheaper Femsa alternative. Barrels were re-worked and could be sleeved for ease of repair, heads were modified, and a floating exhaust system with expansion boxes was allowed to resonate on flexible stubs. The 750 development brought Barton Motors closer to Suzuki and they re-sleeved barrels for the Works racers and also manufactured replacement parts.

The Barton aim was not merely to cater for clubmen racers, so they went head-to-head with the Japenese. The Barton Phoenix was their attempt to make a machine to rival the Japanese is the large capacity classes. The Phoenix was to be produced in 500cc and 750cc sizes.
Phoenix 750cc square four

The Phoenix project started in 1976. The Phoenix was a square four two-stroke which followed the Suzuki RG500 concept. Barry Hart choose not to use reed valves (like the Yamaha 750 utilised) as they restrict performance at the top end. The Phoenix used disc valves like the RG500, as they permit the use of asymmetrical inlet timing.

Although the Phoenix followed RG500 principles, there were some improvements to increase the internal strength of the engine. The Phoenix crankcases have more reinforcement and water passages do not cross joint faces as in the Suzuki. The internal crankshaft coupling was improved (an area of weakness on early RG500s), the gearbox is stronger and the clutch is lighter by using Yamaha 750 clutch plates with improved pressure plate bearings and a less complicated release mechanism. In several places the bearing support and lubrication was also improved over the RG500.

The Phoenix engine was entirely of Barton manufacture apart from RG500 bearings and Yamaha pistons – OW31 for the 750cc and Yamaha 250 pistons for the 500cc. For cylinder liners, the Phoenix engines used aluminium sleeves with chrome bores which drop into the pot from the top where they are located in the block and held by the head. The porting of the Phoenix 500cc was like a 250 Yamaha, whilst the 750cc used OW31 porting but with disc valve induction.

By 1979 approximately ten Phoenix engines had been manufactured (two of which were 500cc). The Barton team were honest by suggesting they “wish to sell these engines to people who are prepared to work with us to solve any problems that may occur”. In 1978 Graham Wood aboard a Phoenix beat Ron Haslam on an OW31 at Donington in a heat. He nearly did the same in the final, until a plug oiled due to an overly rich mixture. By 1979 Barry Hart still regarded the Sparton 500 as a more suitable engine for 500cc GP racing due to its reduced weight than the Phoenix unit.