BMW E21
The E21 was the first 3 series, successor to the '02' range which ran from around 1977 to 1983 and often reffered to as the unloved classic BMW. But they are reliable, handle well (being tail happy) and are considerably lighter than E30s.
Values have started to rise in the past 6 months, so buy one soon if your
going to. According to VOSA there was only 491 3 series BMWs dated 1977
to 82 that passed their MOTs during 2008 - so rare they are!
They come in 4cyl and 6cyl engines, but we'll stick to UK models here!
M10:
The 4 cyl 8 valve m10 engines in either 1600 (74bhp-ish) and 1800 (90bhp-ish) are very hardy engines taking big miles with ease if looked after. Both are Solex carbed engines.
These respond well to basic tuning methods, indeed 130bhp can be seen on
the 1800 units with simple performance cam, exhaust and a Weber
replacement carb mods.
Don't forget turboing these m10 engines took the bmw F1 cars of the 70s
to several victories, having nearly 1000bhp from engines based on the
m10 design!
Retro turbo kits are out there on sale though few and far between - or using home
brew bits and bobs it's been done by several people making 200-300bhp!
M20:
The 6 cylinder m20 engines came in either 2.0 320/6 (120bhp-ish) or 2.3 inj 323i (145bhp). These are very under stressed engines in standard form both capable of silly mileages if looked after. The 2.0 is a Solex carbed engine, the 323i being a K-jet mechanical fuel injection based system engine. Both benefit very well from having their aging fuel and ignition systems dragged into the 1990s with a Motronic conversion from an e30 320i, chipped to suit. Or even better, leave the Motronic 1.3 system attached to a 325i engine and stick that in. It's all just nuts and bolts and soldering (6 wires). This makes a world of difference, with 170bhp the E21 really comes alive.
Engine swaps:
Other engine changes are possible. I've seen 3.5 m30, LS1 V8, BMW V8
conversions. and of course 2.7 m20 ETA engines - not easy or simple though TBH!!
If you go much above 200bhp you'll need a rear diff conversion, as alll E21s had small case diffs and quite weedy driveshafts - and they break. Conversions are either E30 or E12 diff conversions, both involve
chopping up rear beams using the wishbones and driveshafts in different
ways.
Alpina:
There were two Alpina prepped road cars.
The C1 Alpina was merely a 323i with Alpina bits and bobs bolted to it. In England this involved a standard 323i (already at a dealer) and some
boxes of Alpina spoilers, steering wheels, gear knobs and stickers from Germany for UK dealers to bolt on. Hardly worth paying extra for IMO.
The real deal was the B6 Alpina involving a breathed on 2.8 m30 engine
producing 180bhp-ish. Proper Alpina suspension and brakes, dogleg
gearbox, LSD and a Recaro full leather interior all featured in the spec.
Brakes:
Brakes wise, all cars had disc fronts and drums on the rear. 323i though had
discs all round with vented fronts. A popular mod is to fit vented front
discs and calipers from the 323i to lesser models. There are other
budget conversions involving Volvo 240 front 4 pot calipers etc.
ROT is your enemy with E21s. They can rot almost anywhere! Sills, boot
floor, foot wells, anywhere.
So watch out. E21s have either been welded or need it! You have been warned...
Power steering and 5 speed gearboxes are reasonably rare, being a cost
option when new. LSDs are silly expensive too, being very rare things - £400-ish second hand!
Expect to pay.....
A rotten 4 cyl car or 320/6 can be had for a few hundred quid. Easy to
weld it up and 325i it for a few hundered more.
A tidy 323i will cost you £1500-£2500 though.
Mint 323is are 4k plus!
Alpina versions......... dont even ask how much they are!
Any more info that you need, pm me or see www.bmwe21.net.
Thanks for being arsed to read, go fuck yourselves! 
Written by Murran.
