17 replies to this topic

[Malcolm1959]

Hi,

I'm new to this forum.  I'm seeking advice to help improve performance of my November 1959 Austin Seven, which I have re-built as a period rally car.  (I took it for its first event to the H.E.R.O. summer reliability trial last weekend and convinced myself that it could do with a bit more power - it's currently only got 47 BHp).  To comply with the regulations, any modifications fitted must have been available prior to 1 Jan 1960.  Currently the car is running with a standard cylinder head, with c.r. raised to 10:1 and Downton manifold with twin H1 SUs and AEA 731 camshaft.  I would like to increase the valve size, as this would give the easiest power increase, but am not sure whether any larger valves were available for the A series head in 1959.  Looking at the spec of the 1959 rally minis that competed in the RAC rally in Nov 59 and the Monte in Jan 1960, they only used standard size valves - so this is no help.  If anyone out there can point me to literature either by Downton or Speedwell etc showing that larger valves were available, I would be very grateful.  I would need such documentary evidence before I can modify the head - as otherwise the car would be re-classified as a 1960's car and destroy its current advantage of competing as a 1950's car.

Any help will be much appreciated.  Malcolm

[rally1380]

Wow...you're brave rallying a 59 mini!!!! Gonna have the mini mafia after you

 

Edit: Sorry that is no help to you at all.....Cooperman is your best bet for period rally advice as he's old enough to remember what they used...Sorry Pete   ha ha

Edited by rally1380, 25 June 2014 - 08:53 AM.

[Devo]

Hello Malcolm welcome to the forum, I look forward to seeing some pictures of your mini soon 

[keefr22]

I don't know whether he'd be able to help, but we have a 1293 engine from Steve Harris motorsport. Apparently he was a long time employee at Downton, so may be able to point you in the right direction. Or maybe even help you source bits? My son rang him to try & find some more of the spec of our engine when we bought the car, & he was apparently very friendly & helpful, so maybe worth a try? 

 

http://www.bjautobits.co.uk/

 

(no connection at all other than having one of his engines in our car when we bought it!) 

 

Keith

 

PS I echo Devo's request for some pictures...!!

[CobraV8]

Your most power is going to be from the best possible porting and valve area shaping to make the most of the carbs and camshaft. Also look into what you can do on the exhaust side, lightening of flywheel, most likely lower gearing.

[rally1380]

What sort of rallying are you intending on doing?  Is it the HRCR style events?

[miniman24]

The MK1 Conversions forum has a gold mine of knowledge from scans of Speedwell catalogs to mods available year to year, and the guys on there really know their stuff:

 

http://mk1-performan...k/mk1_index.htm

[Cooperman]

Hi Malcolm,

Welcome to our Forum.

It will be difficult to improve any more as even the 1961 rally Minis from the 'works' only had about 47 bhp at the flywheel. I have rallied in a 1961 works-prepared car (the famous 16BOJ) and that had 47 bhp.

During the 4 months from August to December 1959 all the works did was to enter some cars in the RAC rally and not do enough development work to get any sort of result.

Probably the best thing to do is to build it for reliability rather than performance. In 1959, a Mini was as good or better than most things out there with only the Anglia offering any sort of challenge in the small saloon category and that was equally under-developed and lacking in 'grunt' in December 1959.

I had just started rallying back then and an 850 Mini was good for a win on most UK events.

Presumably you have the later crank which doesn't have the oil-fed primary gear and thin tail.

If running twin carbs you can obviously gas-flow the head although bigger valves were not available. You could, maybe, fit Sprite valves as they were slightly larger I believe. The Sprite was built from 1958 so if parts just had to be available then you will be OK. However, if you have to prove 'period use' in the Mini then you'll have a problem. I think the weak 850 crank will limit the power as if you use more than 6000 rpm repeatedly it will snap. In 1960 there was an 850 competition crank introduced which would rev to 7000 rpm, but I doubt you'll fine one now. A 731 cam in an 850 needs to use over 6000 rpm, so be careful how far you go with this.

The big issue will also be the brakes as the 1959 cars had single leading shoe narrow lining drum brakes all round.

By 1961 the Mini was being developed more and 16BOJ was very competitive and was seriously lightened. It had a single 1.5" SU and was still winning area championship rallies in 1963. I won the London Counties Association of Motor Clubs Championship in 1963 in another 850 which I reckon had no more than 40 bhp.

Just don't slow down for corners  .

[Pitcrew6464]

Hi Malcom

Welcome to the Forum! Your mini sounds awesome a very rare gem of a mini I would love to see photos of her
You need to contact Rob Selby on 07770 861615 he specialises in mini race engines and had many successful years building them for competition he also builds rally spec a series engines so the perfect person to talk with as he knows all there is to know, let him know Shaun Tarlton has put you in touch with him, also his website is http://www.selbyengineering.com

[lucas1amps]

good to see another 59 racer best of luck Slark racing engines are very good founded by  Brian slark he specialised in cylinder heads for downton back in the 60/70's. 

[Ivor Badger]

The first thing to do, if not already done, is fit a full set of camshaft bearings. 850s of that age only have a front one.

 

If the mods are time period limited, was a 731 cam available in 59?

 

Are any Formula Junior mods permissible? I would have thought falling back on A30/35 mods of the period was the way to go.

[Cooperman]

What regulations are you running to?

If you want a lot more power you will need to get a new crankshaft made from a billet of steel for starters. That is the only way you'll get the revs to use a hot camshaft and a head with larger valves, twin carbs, etc.

With only an original 850 crank the revs will be limited, and thus so will the power.

It's no good looking at race 850 engines as they run to different rules and will not be acceptable for pre-1960 rallying regulations. You are strictly restricted by the pre-60 rules, or so it would seem, but it seems unlikely that a 'billet steel' crank would be detected unless the engine was stripped by the scrutineers. To some extent it depends on how much you want to play 'by the rules' if you get my drift. If you start beating a lot of other pre-60 cars there will be 'questions in the house' as to the legality of your engine.

By the way, a 731 cam will not be ideal for an 850.

[lucas1amps]

we are building a fast 850 for our 59. you can get 60 bhp without too much trouble.

[Cooperman]

we are building a fast 850 for our 59. you can get 60 bhp without too much trouble.

I bet that wouldn't comply with the rally regulations for pre-1960 cars. You won't get 60 bhp from an 850 with the original split-skirt pistons and valve sizes.

Even the 1961 'works' rally Minis with the competition cranks only produced around 48 bhp. I know because I've navigated one and done work on it.

If you turn up on a rally and enter as pre-1960, then your car has so much more power than any other car in that class, the scrutineers will be all over it to check for eligibility. Remember, a 1959 Mini should have an oil fed primary gear and a thin-tail crank. Virtually no performance parts were homologated pre-1960. That is the problem the OP is struggling with.

Of course, if later Mini engine technology is used, such as a 12G295 head with larger inlet valves, flat-top solid-skirt pistons, billet steel crank, 3-into-1 Cooper exhaust manifold, 'S' lightened rockers, lightened flywheel, duplex timing gears, different cam (not a 731) and other 'goodies' are used it is possible to get around 65 bhp, but that engine will not be either suitable for rallying or meet the pre-'60 regs. 

In fact, to do well in pre-1960 class in a Mini it should not be necessary to have huge power. Reliability, road-holding and handling will mean you will more than match any other small engined car. For example, a 1959 Mini will annihilate a Renault 750 or Dauphine, an Austin A40, a Minor 1000, a 100E Anglia, an Austin A35, a VW Beetle or similar.

Best bet is to aim for 40 to 45 bhp with reliable transmission and good mid-range torque. Then drive it accurately and you'll have a class winner.

Good luck with it.

[rally1380]

 

we are building a fast 850 for our 59. you can get 60 bhp without too much trouble.

 

In fact, to do well in pre-1960 class in a Mini it should not be necessary to have huge power. Reliability, road-holding and handling will mean you will more than match any other small engined car. For example, a 1959 Mini will annihilate a Renault 750 or Dauphine, an Austin A40, a Minor 1000, a 100E Anglia, an Austin A35, a VW Beetle or similar.

Best bet is to aim for 40 to 45 bhp with reliable transmission and good mid-range torque. Then drive it accurately and you'll have a class winner.

Good luck with it.

 

 

Well said Coop's.

 

Power most definately isn't the be all and end all but reliability most definately is....to finish first, first you must finish....or 'start' in my case!!!!!!!

 

The relatively low powered mini can out handle most, if not all cars of the 1959 era, just a case of carrying as much speed as possible through the twisty bits so you don't suffer with the lack of power on the straights.....easier said than done I admit, but great fun!!!