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6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc |
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75 HP Bristol engine.
I own the HRG 2 Litre. The one and only. An experimental chassis built by HRG in about 1948/9 for a Bristol engine. Having got as far as a rolling chassis with an engine borrowed from Bristol Cars, the penny dropped when HRG realised everyone else was using this engine for racing. The engine was, very reluctantly, returned and the chassis ended up with a cousin on a New South Wales sheep station.
To complete the car I found an early 400 engine near Melbourne. It is engine number 1065, stamped 400/75 on that brass plate on the offside rocker cover. Now the Oz Bristol gurus don't acknowledge the existence of a 75 HP engine outside early Filton development cars, so what have I got? I wrote to Tony Crook a few years ago but did not receive a reply. A pity because long ago when I married in London he lent me a 403 for a weekend. Does anyone out there know whether 75 HP engined cars were sold by Bristol and if so how many and to whom? Lewis. |
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75 HP Bristol engine.
Well, my 400 instruction manual suggests that the "touring engine"
produced 75 bhp at 4500rpm and was equipped with a single dual port solex carburetter, whilst the sports engine (with special camshaft) produced 85 bhp and had three downdraught SU`s. This sports engine is usually referred to as the 85A. The engine and was then fitted with three Solex carbs, became the 85C and was used in the 401. The single Solex was fitted to a special manifold connected to the water circulation system. John P |
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75 HP Bristol engine.
> I had an early Bristol 400 - still in existence, but not with me, unfortunately.
The Bristol Parts list (I still have it) which came with the car shows a SINGLE Solex twin choke carburettor with a separate induction manifold. It also shows three SU carburettors, attached directly to the head, to make it an 85A engine, but with a catalogued power of 80 bhp. My engine was subsequently fitted with three Solex carburettors to turn it into a 85AC engine, with a catalogued power of 85 bhp. I'm sure an engine fitted with a single Solex would have given less than 80 bhp, and Setwright's book refers to early 400 car engines giving 75 bhp. But how many of these were sold, I don't know. Best wishes, Brian Kidd> > > > > |
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75 HP Bristol engine.
Lewis and others,
It is interesting that this engine is marked 400/75 The 400- 403 Workshop Manual states "Type 85 engine is 75BHP at 4200rpm fitted with single Solex30 AAPI 85A is 80BHP at 4200 three SU - D2 85C is 85BHP at 4500 three 32 BI You all would have known this , but there is no mention of a type 75 engine ( it could have been a special engine producing less than 75 BHP ) Of the First series 400's delivered to Australia the BOCA has record of eight 85 series engines , most have been converted by fitting 3 SU's or 3 Solex Lewis your 75 series engine is the only one of it's type that I have heard off . I can only assume it produced lower bhp by lower compression or change of camshaft although there is no mention of those parts in the 400 Parts Book . If you look at Ashley's website www.jel450.com there is a Register I compiled of all known 400's . Engine 400/75 #1065 was originally fitted to a first series chassis # 530 which is Car# 266 ( one can assume the 166th type 400 of approx 420 produced ) , although the engine I assume was the 65th produced & unlikely to be a development engine. Chassis 530 is currently owned by Nick Wood in Perth , W.Australia it would be interesting to find out what was stamped on the bulkhead ID plate. BAC did not assemble type 400's , chassis # , engine # or Car # in any order , its a real jumble , unlike later models . I believe that the standard Filton bodied 400's were produced in Car# sequence and Chassis and Engines were just selected from a stock at random. The Blocks of the early engines were different to later 400 engines . At the rear of the block there is a screw in welsh plug rather than a bolt on alloy plate , Lewis does you engine have this feature ? What engine number is stamped on the block near the starter motor mounting ? Does it have a prefix ? We can all have our theories , but as time passes facts & knowledge pass with men that produced the cars. All the inaccuracies printed in the past by so called experts are reprinted and eventually become fact. Regards Geoff Dowdle |
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75 HP Bristol engine.
Geoff,
You could well be right, however my workshop manual for the 85A engine and gearbox clearly shows an engine with three SU`s and quotes 80 BHP at 4200 rpm. The instruction manual (the book supplied with the car) quotes power output figures at 4500 rpm which are 5 BHP higher. Early marketing speak?? John P |
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75 HP Bristol engine.
John,
Standard Engines available for 400's (from 1946 to 1951)were as follows 85 Single Solex STD Cam 75bhp 85A 3 SU STD Cam 80 bhp 85B 3 SU Sports Cam 85bhp 85C 3 Solex STD Cam 85bhp 85AC 3 Solex STD Cam 85bhp ( Note the 85AC engine is possibly a 85A upgraded to 85C spec with change of carbs from 3 SU to 3 Solex. I have never seen reference to this 85AC designation in any BAC produced manual , handbook, partsbook, etc . The only reference I have seen is in the BOC Register . Does any one have a 400 with a 85AC engine fitted who can confirm the stampings on the bulkhead plate , rocker cover plate and engine/head stampings.) There were at least two 400's fitted with a FNS engine from new , number FNS1/5 for the Aldingtons of AFN Ltd. Prototype #2 (Regn# NHX115) which I understand was destroyed in a rally accident . This engine was then fitted to a new car Chassis 600 , but it is not currently with that chassis . Does anyone know of it's current location? Chassis 500 was ordered by W.H. Lowe on Melbourne , Australia in 1948 with a Special Sports engine , with designation 85BS/1592 . It is possibly a FNS type engine stamped as a BS (Bristol Sports) engine . I have not seen the car or engine for many years but believe it has a counter balance 2 in main crank, sports cam , higher compression, 3 Solex carbs ,STD 85 sump and possibly larger valves with about 120bhp(similar spec to the FNS engine 126bhp at 5500 rpm). This engine predates most of the other BS engines by a few years and is unusual that it has 2in main journals . Although in the" Bristol 2 Litre Sports Manual" there is reference to BS1/SC & BS1A/SC engine types which have 2in main cranks . (SC for Small crank ) and other specs similar to the BS1 and BS1A type engines that were fitted to Cooper Bristols , Tojerio's, etc in the early 1950's. As for the 400/75 designation , it is a bit of a mystery . It could have been a mistake by a BAC staff member stamping the rocker cover 75 instead of 85 or another special order engine . Geoff D |
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75 hp Engine No. 1065
Thank you all for the interesting speculation and forgive me for not responding more promptly. We have been shepherding the youngest son through Year 12 exams and, frankly, mounting a takeover for BHP would be easier. His school days over, he will be concentrating on the pursuit of young women and booze.
I bought this engine from Graeme Lowe of Mornington (?), Victoria. It was the usual heap of boxes filled with almost unrecognizable bits of metal. There were no carburetors, manifold or crankshaft. A bloke in Geelong had just made two crankshafts, at the request I believe of Will Bailey who bought one and I was able to buy the other. Colin Young supplied three Solex carburetors and manifold. It looks as if mine was the "Touring" engine with a single carburettor, although as it seems likely to have been the 65th made, not a particularly early one. Why would anyone want to buy a Bristol with a less powerful engine? One presumes the cars were originally bought, as now, by people who generally wanted something better and faster than the usual run. I cannot see what is at the rear of the block. The body is a tight fit and the block is only an inch or two from the bulkhead with the lip of the bonnet rim blocking vision. I'll see what I can do next time the car is serviced. The number stamped on the block by the starter motor is 1065, no prefix. Perhaps Geoff's suggestion of a mistake by the man who stamped the plates is correct. I don't think we'll ever get to the bottom of this. Regards, Lewis |
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Tuning Solex Carburetors
I need some advice.
Could somebody post a short, simple, chlld's guide to tuning triple Solex downdraft carburettors. I suspect Geoff Dowdle may not be able to resist. And nobody is to fall about laughing. I have done it before. When I bought my first 403, back in 1965, I had one of those marvelous carburetor balancing devices and used to happily play with mixture and throttle settings, but the device was sold with the car and I have never found another. Reason for all this is the alteration of the linkage from accelerator pedal up to the carbs to eliminate most vibration when I hit a bump. Inevitably carburetor balance has suffered and I would like to confidently go back to square 1. Regards, Lewis |
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Tuning Solex Carburetors
Until Geoff recovers from his trip to Thailand you could try the
workshop manual, which is a download from www.jel450.com Hopefully you'll be starting with the correct jets which was more than I had. It months and guidance from Geoff to get my 5000 rpm! Ashley |
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Tuning Solex Carburetors
Hi Lewis, There are balancing devices available from Holden. I had the
Balance meter SD/090.33 and there is also a carburettor synchroniser SD/090.043. Go to www.holden.co.uk The only problem with the balancer was that there is not enough room beneath the bonnet for-aft bar so I had a rt. angle plastic pipe joint to use it sideways! Brian |
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Tuning Solex Carburetors
Thank you Ashley James. www.jel450 was exactly what I wanted. Having read the relevant bits of the manuals I now remember what it was I did so many years ago. Now if my youngest son (who is at that wonderful age where he knows everything) will spare a moment to persuade my computer to correctly size the pages for printing I will be in business.
Regards, Lewis |
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Tuning Solex Carburetors
And thank you Brian Cuddigan. Christmas is early this year. I recognise Holden's carb. synchroniser and will have no trouble using it as my small bonnet lifts off, no hinges. I will discuss synchroniser and balancer with my local garagiste. A wild man in his youth (once apprehended by police for driving to work at 130 mph in a 60 zone; having set up roadblocks to catch him they couldn't prove his speed and he got off) he has endured years of servicing Japanese jelly moulds and was intrigued when I came along with the eccentric HRG Bristol. He now looks after six Bristol engined cars, says they are beautifully built and easy to work on and plans to expand his business. Minions will endure the bread and butter work while he plays with proper cars.
Regards, Lewis |
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Tuning Solex Carburetors
Lewis,
it is quite a lengthly process to try and correct 50 plus years of abuse on those old Solex . The most important things to look for before you start tuning as per the manual is ...... 1. Are the 3 carbs the same , especially the throttle bases, make sure they all have the same number of progression holes ie 2 for 401 - 405 , 3 for 406 & D2 . All faces must be flat including the adapter the carbs bolt to. 2. Float levels MUST be at 16mm down from the top of the main body when the engine is idling, this can only be measured by making up an external plastic sight tube attached to a spare main jet holder. The levels are adjusted by shimming the needle & seat unit in the carby top . Note machining of the carby tops can be different different for different Solex applications. 3. Make sure the jetting is correct , ALL JETS & Emulsion tubes. Check the diameters with various size metric drills. Many original jets have been incresed in size over the years by drilling out . As a rule you should need slightly leaner jets than STD as the quality of modern petrol is so much better than the very poor petrol of the late 40's and early 50's 4. I usually replace the nice brass AMAL throttle rod ball joint ends(usually badly worn) with new ones to allow the throttle butterfly's to go back evenly on the adjustment screws. 5 Although not directly related to Carby tuning , valve clearance must be correct, distributor MUST be in good working order , advancing correctly . Very few Lucas distributors work well even when new, they were poorly made. (BAC used Delco Remy twin point for all the BS engines) I usually replace the Lucas with a modified Malloy twin point unit, thats is fully adjustable. There is no point in converting your Lucas to electronic operation while the advance curve is no where near correct. You must have a TDC make on either the flywheel or fcrankshaft fan belt pulley to operate a timing light . 6 Unless you do most or all of the above you will never get a 6 cylinder Bristol running nicely. Must go, Good Luck Geoff Dowdle I |
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Tuning Solex Carburetors
Panic over. The little HRG Bristol is running like a Swiss watch. I downloaded
the JEL450 Bristol Carburetor Tuning manuel and employed the Holden Vintage and Classic UK balancer that arrived in the mail this morning. The years fell away and I was back playing with my first 403 in 1964. So simple; disconnect everything, wind it all back to scratch, factory settings, reconnect linkages identically with finest possible tolerances, a little adjustment and I might have a turbine under the bonnet. Only two snags, the local garagiste, who is now caring for four Bristols, has appropriated the balancer and I have had to order another from Holden, who are terribly excited and have sent me twenty emails in as many minutes. Lewis. |
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Tuning Solex Carburetors
I just bought one! I've the car almost perfect but know from
balancing motorcycle carbs how important it is to get the throttles exactly the same. I was going to use a Morgan Carbtune through holes in the pilots jets, but this is easier. Holdens are the most expensive company on the planet along with Frosts, but they do sometime have things you can't find elswhere. Ashley |
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Tuning Solex Carburetors
To tune the Solex correctly you have to balance the air flow of each carb
, and balance the vacuum on the idle system with in each carb . If you have a 404/405 Workshop Manual there are details on how to do this . Most owners use a Holden type air flow balancer and then just screw the idle mixture screws in or out until the beat of the engine changes then screw it out about half a turn ,this gets the idle mixtures pretty close. But the 404/405 manual has detail instructions of how to make your own triple Manometer , using this the airflow of the three carbs can be adjusted together (as adjustment of the airflw of one carb can slightly adjust the air flow of the other two ) . Once the airflows are matched you use the triple manometer to balance the vacuum at the pilot jets , this is adjusted by screwing the idle mixture screws in or out . Then if the carbs are a matched set , jetted correctly and in good condition you have a chance of tuning the old Solexes correctly . IT IS WELL WORTHWHILE TAKING THE TIME AND VERY LITTLE MONEY TO MAKE YOUR OWN TRIPLE MANOMETER. Every 6 cylinder Bristol owner should have one. Geoff |
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