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1934 BSA 10hp RWD

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JGuppy
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Joined: Mon Aug 05, 2019 12:59 pm
Location: Hastings , East Sussex

1934 BSA 10hp RWD

Post by JGuppy »

Hi everyone
I have just purchased myself a 1935 BSA 10HP RWD Saloon and looking for a few items Can anyone help

BSA owners handbook ( inc Wilson Gearbox )
Wheel Brace

The previous owner has replaced the Solex carburettor with an SU carb and it lacks power so I was considering replacing it back to the original Solex carb
Does anyone have a spare complete carb and air cleaner

also wanting to make contact with other owners I am also a member of the BSA front wheel drive club

kind regards
John
Hastings
East Sussex

Sydsmith
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Re: 1934 BSA 10hp RWD

Post by Sydsmith »

Hi John sorry I cant help with what you need but wanted to say congrats on a great motor, hope it goes well for you. Syd

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John-B
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Re: 1934 BSA 10hp RWD

Post by John-B »

JGuppy wrote: Mon Aug 05, 2019 1:45 pm
The previous owner has replaced the Solex carburettor with an SU carb and it lacks power so I was considering replacing it back to the original Solex carb
Does anyone have a spare complete carb and air cleaner
Really? :o Read this topic where a LA11 owner has got rid of a Solex and replaced it with an SU. Probably different carbs and a different car, but worth reading all 15 pages: http://forum.dloc.co.uk/viewtopic.php?f=5&t=4027

Also it might be worth contacting the BSA registrar Mark Cuthbert Brown username Redcap .

Welcome, we haven't got many BSA members.

JT7196
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Re: 1934 BSA 10hp RWD

Post by JT7196 »

Hi John if you Really want s Solex Carb then let my know .

Cheers Al 😊

JGuppy
Posts: 5
Joined: Mon Aug 05, 2019 12:59 pm
Location: Hastings , East Sussex

Re: 1934 BSA 10hp RWD

Post by JGuppy »

Hi
I can see where you are coming from people have fitted the SU as being better hence I guess I have an SU I would very much like to restore the car to original spec hence looking for a carb and air cleaner , as I am new to this site and its difficult to talk to other owners due to there being so few but I would be interested in your thoughts and views on the subject

Do you have a wheel brace by chance
regards
John

Sydsmith
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Re: 1934 BSA 10hp RWD

Post by Sydsmith »

Hi John. I have a similar problem with my Daimler 15 only the other way round, in that originally it was fitted with an SU carb but some time in its life a Solex has been fitted, a long time ago from the state of it so the engine must at some time have run well with it.

The problem I have with the Solex is that I cannot get it to set up correctly, I and others have tried but with everything screwed down as lean as possible the engine still runs very rich.

After a long search I have found an SU HV4 which is the correct carb but have yet to fit it.

My other two Daimlers have SU carbs and they are so easy to set up, the Solex is not at all easy by comparison.

Simon Hyslop

Re: 1934 BSA 10hp RWD

Post by Simon Hyslop »

If anyone on here has a Solex carburettor which uses jets roughly the shape of a standard size Meccano bolt, but about half as large again, let me know the size you need and I will look through my boxes of jets and if I have what you need, they're yours for the postage cost. I have several matchboxes full of them but those are the only pattern I have.

For what follows, please accept my apologies in advance if some or all of it is already known to you but it is intended to be potentially of some help if help is needed.

I had hoped one of my books would have said what model of carburettor was fitted to the BSA 10 but unfortunately they stop in the middle 30s with exact models. The problem with Solex and Zenith carburettors of the time is that they are exceptionally model specific and so something that superficially looks "the same" has the wrong size choke (not the starting mechanism choke - the cast in air intake diameter) , the wrong jet or jets and on it goes. Early Solexes have a single jet that, when removed, allows the carburettor to come apart but there is also a submerged jet and it's extremely unlikely that a random Solex will be the right one for a BSA or even modifiabale to become the right one. Even Rolls Royce eventually had to accept the values of the SU carburettor and moved on to using them and Standard Triumph asked Zenith to make a copy SU (the CD Stromberg) to avoid being dependant on BMC for this key component.

I accept I am fairly pessimistic about the chances of finding some of these items and I am sometimes proved wrong (fortunately) but some of these items were made in desperately small quantities to start with and owners in the 1940s and 50s had already exhausted many of the spares knocking about.

I mentioned in another post on here a quote by Henry Ford and it's completely by chance that another one of his comes to mind with the SU design. He said he could have "made a better carburettor out of two tin cans" but in truth, I have to concur with the view that for simplicity, easy tuning and reliability, there is nothing to beat an SU.

I am interested in the question of the BSA not producing enough power. I would not normally ask this as a first question but feel it worthwhile asking , how do you know ? A side valve Austin 10 of the period has a similar sized engine with a much smaller and lighter body and transmission system. They run out of steam on hills that are virtually invisible to the modern car and the addition of any passengers means a lot more changing down. I know that my own LA10 isn't exactly over endowed with power so I just ask whether the car just feels very slow in comparison to newer cars or slow in comparison to other BSA 10s.

However, if it is down on the power output you might expect, the problem can really only be one of three things, assuming all other incidentals such as spark plugs etc are correct and the engine itself is in good condition :



1) Incorrect needle

2)Restricted or over rich fuel supply

3) Ignition timing

Unfortunately, neither in their printed catalogue nor online do Burlen Fuel Systems specify the correct needle for a BSA 10 fitted with an SU. That would lead me to think that it may be unlikely that a previous owner has found exactly the right needle. Burlen may be able to help if you contact them direct and explain the situation. If you can read the small writing on the needle, it will say what it is and with that information, it can be deduced what it may have been fitted to. There is a booklet which details all the SU needle dimensions, measured at 13 or 16 points along the length of the needle depending on whether it's an old fixed type needle or the newer spring loaded type. They are extremely precisely made and the wrong needle will certainly lead to poor performance or economy, or both. I have one of these somewhere but a longer search would be needed to find where it ended up in The Move 2 years ago !

If I was looking for a starting point, I'd maybe try a D4 needle, or an M6 or an M9, assuming an OM carburettor. These were the standard needles for a Riley 9 , a 1930 Rover 10 and a 1933 Standard 9 respectively. If I could find that little book, I may eliminate one or two of these but on paper and thinking about the engine sizes, one of them would maybe be 'close enough'.

If there is a specific point in the power range that your car lacks go, the other possibility is to carefully file a bit off the side of the needle you have. You may wish to use another needle of the same specification to try this on as the process is not reversible (!!) but taking a very little off from the top 1/8" under the shoulder will enrichen the starting off mixture and working down another 1/8"-1/4" will enrichen the acceleration on the go. This first 1/8" or so is the most critical This can work reasonably well on a single carburettor car but doesn't do on a twin carb car because you can't really replicate the dimensions precisely enough to balance them.

If the jet has been adjusted too far down on an SU to compensate for a needle that is too lean at tickover, it would be too rich for normal running and would reduce the power output. Recently I was faced with a car that had a stutter every so often, sometimes leading to a complete stop and then it would go again. The trouble seems to have been (I hope) a new fuel pump which had a defective valve and on dismantling the pump, one of the little valve springs fell out. It had enough petrol to start and sometimes run but not enough to meet the demand when needed.

Ignition timing is maybe unlikely, especially if it starts well enough, but just finding the right spot can sometimes be slightly elusive for good running.

The one application I have found a Solex good for (sorry for repetition as I will have written this before) is on the postwar P2 Rovers. The downdraught SU is such a bother when the piston sticks and the Solexes on the post war ones eliminates that trouble, fortunately.

It would be very interesting to hear how you get on with your car as there are fewer places now for new owners to go and find answers to what ails an older vehicle and the internet resource is probably going to be depended on more and more and we need to keep the cars mobile for the road.

JGuppy
Posts: 5
Joined: Mon Aug 05, 2019 12:59 pm
Location: Hastings , East Sussex

Re: 1934 BSA 10hp RWD

Post by JGuppy »

well perhaps I am wrong did the 1934 BSA come with an SU carb as all I have is information as in the drivers handbook it may be that I should leave it as it is

JT7196
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Re: 1934 BSA 10hp RWD

Post by JT7196 »

Hi Simon, as you know I have fitted a HS2SU to my Lanchester 11 , I have found Burlens to be most helpful and a mine of information re Jet & Needle sizes for any specific model.
I have just been in contact with them , as I have noticed that I need very little Choke when starting from cold, yet when I weaken the mixture by means of the Mixture Adjusting Nut, the Engine starts to “hunt” , Burlens suggested that I fit a Weaker Needle so have just ordered one, will be interesting to see how this works out.
Will let you know how I get on .

CheersAl

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