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Re: 3 bearing engines.. just what IS the truth?

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

Re: 3 bearing engines.. just what IS the truth?

Martin Field
Hello all,
as some may know, I had planned my Cambridge Special to have a Sunbeam 928cc engine, a la Coventry Climax, but today I find that the gearbox won'tgo near the A78 chassis and I'm not even sure if the engine will. I think they're bigger than the 750 CC engine currently in vogue in the racing fraternity.
Not being keen to have adaptor plates made and all that jazz to fit an A7 gearbox and not keen to pay out what I recently did to rebuild a Reliant 850 engine all over again, I am thinking perhaps I'll go for the 3 bearing, unused fire pump A7 engine I acquired recently.
So, if we do (the Special is now a joint thing twixt me and my son, tell us, what is so very bad about the 3 bearing lump? There are, after all, a lot of people happily bumbling round in their Rubies, Pearls, Opals, vans, Specials, etc.

If it is a real no-no, then we will have to go the Sunbeam route.

Martin


Read this http://www.speedex750.co.uk/index_files/Page2152.htm

Location: Shropshire

Re: 3 bearing engines.. just what IS the truth?

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

Re: 3 bearing engines.. just what IS the truth?

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