Lifespan of refurbished Austin 7 engine

[Lowbarn]

From a new Austin 7 owner.

How many miles do people put on a refurbished engine before it needs another rebuild?
Provided it’s treated with respect?

I’ve heard that some of these cars rarely see the light of day. Just wondered if it’s down to the running and maintenance costs needed to keep the old cars mobile.

Richard.

[Parazine]

I reckon that an engine, rebuilt with new everything should last about 40,000 miles before a re-bore becomes necessary. At that mileage, the bottom end, with modern oils should still be fine, although the rear main may benefit from a new bearing. This is based on my use of a Seven in the seventies and eighties, where it was my only transport. In those days, valves were an issue - with leaded petrol, frequent attention was necessary as the lead deposits lifted the exhaust valve off its seat, causing it to burn.

If you use a well fitted air filter, the mileage will go up, perhaps 70,000?

I have a pre-war book on engine rebuilding that reckons 2 1/2 thou bore wear for every 10,000 miles so this tallies quite well.....

Vintage blocks seem to be made from better quality cast iron, so may last a little longer.

[Reckless Rat]

With infrequent use (which is generally the case these days) a properly rebuilt A7 engine should last for years and years providing it is used occasionally, driven sensibly and properly serviced. My own is used pretty regularly but it's not a daily driver. Since a rebore in 2019 it has covered around 5000 miles, including a 2000mile return trip to western Spain. I reckon it's now just nicely run in.

I doubt if I'll still be around when the next rebuild is due.

[Bob Culver]

Prior to the anti acid and other features of oils of the 1950s and thermostats wear of most engines was considerable. Near all makes  were rebored at soem satge. Now .0025 in 100,000 would be a lot in a modern or even a 1960s car.
Condensation from cold running was the death of main bearings; probably now less so with anti corrosive oils. Valves were a trial; part due lead and many cars had mere XB steel or lesser. My car run extensively on the main road needed attention about every 5000 and others reported the same at the time. I presume current valves are of current materials.

[Lowbarn]

Sounds encouraging so far.
I achieved 300 happy miles last year, until last week it’s turned into a workshop project.
Still if I can get it going again, Sounds like I could get a lifetime (mine!) pottering about.

[Peter Naulls]

My special managed 25000 enthusiastic miles before it seized due to an empty radiator. Other than the damage there was minimal wear anywhere and it used virtually no oil. I reckon it would have happily done the same mileage again given the chance. The bottom end and has now done another 5000 miles.

I wonder with the small annual mileages our cars do whether the question should be how many years between rebuilds rather than how many miles. Standing around can't do the bores and bearings any good.

[JFaulknerUlsterRep]

I managed 7 years with the ulster rep until it really went loose and dropped the rods. Mind you I was chasing Dave wilcox in the speedy to Curborough at the time! That was just a bodge up engine. Have now rebuilt and used a quarry engineering rebuilt top end complete with new pistons. Bottom end was a standard Austin crank crack tested and ground by Tony Betts. Rods were white metalled by John Kirkby and then I found a ruby head to finish it off. Also to add we had the front lip on the crankcase repaired and that was all completed in 2012. Steady miles and not thrashing the daylights off it she’s still good today.

[David Stepney]

I have reason to believe that the mileage on my own car, an RP saloon in standard trim now standing at (1)12500 miles is genuine. When I bought the car in 2018, the indicated mileage was 94000, so I have covered about 18500 miles in 3 1/2 years. Shortly after I had the car, I fitted a new rear main bearing. Subsequently, the engine developed a little end knock, so the engine was more thoroughly overhauled. It was found that it had been rebored to 20 thou, and that the bores were in good condition, requiring only sufficient honing to deglaze them. The bottom end was in excellent condition, the crank being the original (it has the engine number stamped on it) and not reground. A quick check with a micrometer showed minimal wear, and the big end bearings were in excellent condition. The engine was reassembled with new gaskets, new pistons and the valves were ground in. Since then, the car has covered about 12500 miles and has been totally dependable. Oil consumption is about 500 miles per pint, but I suspect that it leaks most of this from the tappet cover.

I use a good quality 10W 40 semi-synthetic motor oil, changed every 2500 miles.

It appears that, with care, these engines can be very long lived!

[Parazine]

I doubt if I'll still be around when the next rebuild is due.

With my current annual "Seven" mileage around 2000, split between two cars, my 40,000 estimate will last me 40 years, by which time I'll be 105!

[Malcolm Parker]

I doubt if I'll still be around when the next rebuild is due.

With my current annual "Seven" mileage around 2000, split between two cars, my 40,000 estimate will last me 40 years, by which time I'll be 105!

That'll do, as they say in Yorkshire.