I think it all got a bit gloomy and even off thread yesterday. I was pleased to read Ray's input above. Martin was after "the truth" which I think comes in three parts: 1) if fitting a 3 bearing engine into a special, beware of the potential to put strain on the crankcase as described above 2) the crank must be free of cracks, as shown by magnetic particle inspection (MPI test), and be true
3)getting the centre bearing in line is crucial - the crank must spin freely before moving on with the rest of the engine assembly - see the Speedex notes.
In other words it demands good engineering. Tony Johns made 3 brg engines race!!
Regarding cost/availability of cranks you need to belong to the Bristol Club!! We have more than you can shake a stick at for very low prices! After that it's up to the member to check out that it's got potential!
I suggest Martin strips his engine sufficiently to see how freely the crank spins and determines (by "Speedex method") if there is excess clearance of the centre main. If it looks OK and spins OK I would take a gamble on the crack aspect if he is confident of low useage.

Ron

Location: Thornbury

Location: Shropshire

Sorry Martin, Ian is right. You simply can't run Austin Sevens on a shoestring these days if you want something that is usable and reliable. Of course you can build more modern engines etc. for far less than a Seven. That's because parts are more plentiful for the more modern engine. With scale comes economy. If you want to run your three bearing engine with any degree of reliability then I sincerely hope it works for you. I've been around Sevens since I was 14 years old. I'm now 61 and I wouldn't touch a three bearing engine but that's my experience. I hope yours is different. That experience has taught me that the only way to properly do something is do it once, do it right. Most of us have run cars on a shoestring and have learned that it's false economy in the long run. Breaking a crank is one thing. It's the damage it does to the rest of the engine that is the real consideration and that can be considerable. Been there, done that and very much hope I don't go there again.

Sorry if you found Ian's comment about the Corsa offensive. Frankly, I thought it realistic. However, calling Austin Seven engines 'silly little' things might be considered a touch offensive by some - particularly when they might have been involved with them for most of their lifetime. You asked for opinions about three bearing Austin 7 engines. You got some. They don't suit you but we can only give our considered view based on experience. To do anything else would be incorrect.

Steve

Location: Nr. Selby, North Yorkshire

There are very few alternative engines that will fit in an Austin 7 chassis.

I fitted a SAAB 3 cylinder 2 stroke engine + Austin 7 gearbox in a Box saloon for Barry Argent. It was dreadful!
He soon took the Saab engine out and fitted an Austin engine. The saloon was converted to a sort of 6' 3" RP but he never resolved the problem of very narrow doors, so he used it without. I wonder where it is now?

Previously Barry had an Austin 7 pick-up with a BMC 'A' series engine. Of course the engine would not fit in the chassis so it sat on top and drove the back axle through a modern prop shaft working at extreme angles.

I don't think the Hillman Imp or Reliant engine will fit in the chassis.

750 formula cars generally got rid of the forged nosepiece and used a space frame built with the chassis members wider apart .

Don Rawson has been racing a 750cc Coventry Climax engined Austin special for some years. http://www.750trophyracing.co.uk/the-formula/9-1-sporting-regulations-general.html

There have been quite a few specials built recently using a Big 7 chassis. This chassis has a much larger space at the front of the chassis and it is possible to fit all sorts of engines.

Location: Oxted

Martin, I wanted a period engine for my special and like yourself it had to be done on a budget. I fitted an 1172 Ford e93a. Not too difficult to fit and was common practice in the 1950's. Limited to 3 gears though!
I will add that the whole project was built from bits, and a complete car wasn't destroyed!

In view of the high cost of an engine rebuild has anybody considered fitting on air filter, particularly on cars with updraught carburettors to stop all the dust thrown up by the front wheel from being inducted to accelerate engine wear?
This would be relatively easy with the 24T2 carburettor but would mean disabling the choke on a 22FZB and 26VA. I noticed this when watching a saloon driving down a dusty road during our glorious summer.

By 1930 the Colonial FZB had an air filter and 'air strangler' fitted - although I have only seen a few here.

Tony.

Location: Malvern, Melbourne, Victoria, Australia .

Im new to the world of tuning small Austins, and have read this thread with interest, However Im not new to tuning, Having spent most of my car life with 105E Anglias and Cortinas, I have never broken an engine, except for a split liner, I used to experiment with parts from different engines, Things like Datsun 180B cranks in crossflows, gives you a forged stroker crank and 1800+cc. or even the Fiesta Diesel crank offset ground will give you a good crank, but a lot of work to get the weight down.
What Im saying there must be other ways to build a strong engine, I have not done any research, but Fords made a couple of 3 bearing engines which are still easy to find and not expensive, 100E, the early Anglia 105e and Classic all had 3 bearing engines. Counterbalanced too, They all may be dimensionally be miles away, but Being an Engineer, I tend to "look outside the box". Another option I suppose could be a billet counterbalanced crank made to Austin dimensions, probably cost prohibitive, but an option. going this way gives you an option on on what rods to use, you could find some quality OEM forged rods, even forged pistons that could be modified to fit, make it long stroke you bring up the torque, which is acceleration, make it short stroke, you put the HP up with revs, which gives speed.
Sorry if this way of thought causes upset, But A7s have been modified since their inception, perhaps not with as much Foreign internals, Im just offering suggestions.

Location: United Kingdom

Ah so somebody knows what the export air filter arrangement looked like. The list of spare parts shows a 22FZB without strangler, an air filter with no visible strangler, an export air strangler control rod BE 90 and different accelerator control parts to clear the filter. So how was the strangler arranged Tony?

I assume it was like a throttle butterfly, but I have no idea how it was assembled.

Tony.

Location: Malvern, Melbourne, Victoria, Australia .

Ian

Your background sounds very interesting!

However with regard to Austin Seven engines I don't see the need to reinvent the wheel....

We have available the various Pheonix cranks in splash and pressure feed and 2 different diameters, plus there are a number of rod choices to pick from.

A combination of the above will build a reasonably bullet proof 2 BEARING ENGINE!!!

The 3 bearing as discussed in this thread is another matter entirely, but as there are not many used then most people just use the 2 bearing with the aforementioned parts. You can I believe convert a 3 bearing case to a 2 bearing crank and therefore use a Pheonix 2 bearing crank in it.

As for using proprietary parts then the older Reliant engines have certainly had internal bits robbed in the past..... Look in the Green book and fitting a Reliant crankshaft is covered in detail, but of course this is largely irrelevant today as the arrival of cranks like the Pheonix and associated rods have made it simple and easy to build up a good bottom end.

Mind you I have to say I like your thinking and there are always some new ideas going to surface, trying to take advantage of modern materials and build techniques, particularly for budget builds.

Steve

OK - here goes with my two bob's worth:

I don't race any of my A7's so they aren't subject to racing or competition stresses however...

If I own something mechanical such as an A7, then it has to work. It has to start and run when I want it to and take me where I want to go (within reason) and with a good chance of getting there. If it doesn't, then it either gets sorted until it behaves or else it goes the journey.

When I bought an A7, I joined the club, listened to sage advice, read all I could and then made my own mind up. Two of my A7's originally had 3 bearing engines. I had both of them fully rebuilt by Ian Bancroft who converted them to 2-bearing engines and fitted Pheonix cranks. They should outlast me easily and I do not expect in my lifetime, to ever see a broken crank or a rod coming out the side of the crankcase.

I consider that if you want to enjoy running a 70+ year old car such as one of our A7's, then it will cost you. How much depends on what you want to do with it and how much you are prepared to spend. But it is an inescapable fact that it WILL cost you.

Sic factum est.

Location: West Torrington

Hi
My Ruby has a three bearing engine in it. The block is dated February 1937 and is sleeved and bored again to +20 thou. I have now driven this car for over ten thousand miles, with just one top end overhaul, but no other serious attention. I must admit that I often wonder how long the crankshaft will last – I would certainly feel more confident running a two bearing engine with a Phoenix crank in it, given all the reports of crankshaft failure with three bearing engines. However, some of these engines must have done 100,000 miles or more (though perhaps not on one crank), so is the problem that the remaining crankshafts are tired by now? What would be the likely life expectancy of a newly manufactured three bearing crankshaft in a well set up engine?
Regards
Colin

Location: North Cheshire

Colin

A properly set up 3 bearing engine with a new crank should be more durable than a 2 bearing.

There are three basic problems

One is that new 3 bearing cranks are currently basically unavailible unless you have a one off made. I suppose you could say that they are availible at a significant cost, but so prohibitive that owners tent to hack the crankcase and fit a 2 bearing.

The second is the issue with the middle bearing being out of line, there are various 'dodges', most of which are in engineering terms ****. A proper job needs money spending with a machine shop, or the kit to do it yourself. This adds to the cost of sorting a 'proper job', and is another reason owners go for the 2 bearing conversion.

The last is the lubrication issue with the middle bearing, this is really a simple fix.

That's one that hasn't broken in the last 20 years then, Fred.

Ian Mc.

Location: Shropshire

As mentioned above , a well maintained 3 bearing engine should be good for 1000s of miles, if it is driven with some respect, yes an Austin 7 will do 55/60 MPH but continuous use at these speeds as many are will soon see it break, It is rather like driving a modern on the red line all day and every day. The desire to keep up with modern traffic is strong and many get used to hearing the engine screaming and think of it as a natural way of driving, which it is not! Treat a 3 bearing with respect and it will last for years.

Location: Pembrokeshire

Hi Martin,

I built my special with a 3-bearing engine which I have used aggressively on VSCC driving tests and on the road for over 5 years. I used standard engine mounts on three of the feet and an arrangement with rubbers then big washers and a valve spring before the nut on the final foot. I had not issues other than over carburation by using an HS2 SU on what is a standard engine.
I have recently changed to a highly tuned engine and removed the 3-bearing as a going concern and backup should I ever have any issues with the other engine.
I do agree with one of the other commenters that running A7s is no longer a shoestring operation.
I may consider selling my spare 3-bearing in the future as its just sitting on my engine stand with all ancilliaries etc.

David