Engine Rebuild Pt.1

Take your BMC ‘big four’ to pieces sensitively and systematically

Theo strips down BMC’S B-series.

Lift the bonnet of any mid-range or sporty Austin or BMC car built between 1947 and the early Eighties, and you’re likely to clap eyes on a B-series. Built from cast-iron, granite and Britishness, what this overhead-valve straight-four lacks in sophistication it makes up for in elegant simplicity. It proved flexible enough to grow from 1200cc to 1489cc, 1622cc and finally 1798cc. Later incarnations gained five rather than three main bearings, allowing the original 39bhp to swell to 200bhp and beyond in the hands of tuners.

The B-series is about as simple as it’s possible for a four-stroke four-cylinder engine to be, so rebuilding one at home is a straightforward proposition. Parts supply – particularly for variants installed in MGBS – is second to none. If you’ve never tackled a full engine rebuild before, a B-series is a perfect place to start. Over forthcoming issues of Practical

Classics, we’ll be demonstrating how to restore a tired B-series to better-than-new condition in your shed. We’ll be using nothing more than a basic toolkit, plus a few specialist items that can be bought new for £20 or less. In this issue, we’ll guide you through the strip-down process. After this we’ll cover assessment, writing a shopping list, sending parts off for machining and, finally, putting it all back together again.

Workshop feng shui

Make plenty of space in your workshop before you start, as the engine will expand dramatically as you take it to pieces. Work methodically, make notes, take photographs and loosely replace nuts, bolts and washers after removing components. The engine may look simple as you strip it, but after a month or so of waiting for parts and machining, things won’t seem so clear.

Thanks to Moss Europe (020 8867 2020, moss-europe.com) for expert advice.