BMW E30 323i Spec Comparison to contemporary early-80s rivals...

How does the E30 stack up next to its five most common early 1980s stablemates, the MG Montego Turbo, Peugeot 505 GTi, Renault 25 GTX, Saab 900 Turbo and Subaru RX Turbo?

Great review from MOTOR Magazine, November 1985.

BMW E21 323i Baur wins HERO-ERA Summer Trial

I've been interested in HERO (The Historic Endurance Rallying Organisation) since owning my red E21 and had intended to enter that car in one of the smaller events, as they host a few throughout the year. The big one is the Summer Trial in June and it was nice to see another E21 taking first place this year. A Baur cabriolet no less. Better late than never to throw up a pic of Angus McQueen and Mike Cochrane's HERO winning 323i...

Pic: Classic & Sports Car Magazine, Aug 2021

HERO EVENTS & ERA EVENTS - The Original Classic Rally - https://www.hero-era.com

BMW Bosch Fuel Injection System Trouble-Shooting Guide

SYMPTOM:	PROBABLE CAUSE:
No cold start	Fuel-pump fault or clogged fuel-filter
	Additional air-valve not opening correctly
	Start-valve not opening correctly
	Leak in fuel system
	Throttle-valve plate not opening correctly
	Temp.-sensor fault
	Diode-relay fault
Poor hot start	As above then:
	Leaking / faulty injector
	Heat/time switch fault
Poor idle	Baffle-plate stop wrongly adjusted
	Leak in Vacuum-system
	Fuel-filter clogged
	Mixture-adjustment incorrect
Backfire from engine	Weak fuel mixture
	Fuel pressure too low
	Starter-valve leaking
Engine runs on after shut-off	Leaking / faulty injector
	Stiff/stuck baffle-plate
	Stiff/stuck control-plunger
Excessive fuel consumption	Control pressure too low
	Starter-valve leaking
	Leak in fuel-system
	Fuel mixture too rich
	Heat/time switch fault
Idle-speed too high	Control pressure incorrect
	Additional air-valve stuck open
	Baffle-plate stop wrongly adjusted

Detailed maintenance guide / diagrams in this post [L-Jetronic] - https://www.beemerlab.org/2020/03/bmw-bosch-l-jetronic-fuel-injection.html

Bosch K-Jetronic injection-system overview / diagram here - https://www.beemerlab.org/2019/11/e21e12e28-bosch-k-jetronic-fuel.html

Bosch L-Jetronic injection-system overview / diagram here - https://www.beemerlab.org/2019/11/e30e28e34-bosch-l-jetronic-fuel.html

BMW Bosch L-Jetronic Fuel Injection - Strip-Down / Maintenance Guide + Diagrams [E30, E21, E28]

Throttle Housing:
1. Disconnect the cables (1, 2 or 3) as applicable - Fig. 1.
2. Pull off the vacuum hoses, the coolant hoses (1 and 2) - allowing the coolant to drain - and the air hoses (3 and 4) from the throttle housing - Fig. 2.
3.Remove the vacuum hoses (1 and 2), and the air hose (3) and pull off the multi-pin plug (4) - Fig. 3.
4. Remove the fixing nuts and take off the throttle housing. Do not separate the throttle switch from the housing, as a special gauge will be required to adjust it when refitting.
5. Refitting is a reversal of removal. Use a new gasket and bleed the cooling system.

Throttle Vacuum Control:
1. Pull off the hose (1), release the nut (2) and remove the vacuum control (3) - Fig. 4.
2. When refitting, adjust dimension (B) to between 32.8mm and 33.2mm (1.291" and 1.307") using screw (4).
3. Adjust dimension (A) to between 2.6mm and 3.0mm (0.102" and 0.118") using screw (2) - Fig. 5.

Control Unit:
1. Open the glove compartment and pull the pins from the retaining straps.
2. Remove the screws and place the glovebox cover to one side.
3. Depress the retainer (1) and pull out the multi-pin plug (2) - Fig. 6. Remove the control unit.

Air-flow Sensor:
1. Release the clamp and pull the duct from the air-flow sensor.
2. Disconnect the multi-pin plug, unscrew the fixing nuts and withdraw the sensor.
3. Refitting is a reversal of removal. Renew the seal if necessary.

Temperature Time Switch:
1. Pull off the plug, then unscrew and remove the switch.
2. Refit the switch using a new sealing washer.

Coolant Temperature Sensor:
1. Pull off the plug and unscrew the sensor. Refit using a new sealing washer.

Cold Start Valve:
1. Pull off the plug (1) and disconnect the fuel line (2) - Fig. 7.
2. Unscrew the mounting bolts (3 and 4) and withdraw the valve.
3. Use new seal when refitting.

Fuel Injectors:
1. Unscrew the four injection tube bolts and push the tube upwards until the fuel injectors have cleared the guide in the intake manifold.
2. Pull off the plug (1) and take out the circlip (2) - Fig. 8.
3. Take off the fuel injector.
4. Refitting is a reversal of removal; use new O-ring seals.

Throttle Shaft Return Springs:
1. Disconnect the throttle, kick-down and cruise-control cables. (The latter two where applicable.)
2. Remove the retainer (1), washer (2) and disconnect the linkage (3) on the lever (4).
3. Raise the lever and turn it to relieve the spring tension.
4. Remove the lever.
5. Remove the spring.
6. Disconnect the spring (1) and unscrew the nut (2) - Fig. 9.
7. Remove the washer (1) and lever (2) - Fig. 10.
8. Remove the sleeve (1) and spring (2) - Fig. 11. - also the wave washer.
9. Reassemble in the reverse order to dismantling and adjust in the following way - Pull off the tamperproof lock (1) and loosen the screw (2) until the lever (3) no longer rests on the screw - Fig. 12.
10. Place a finger on the lever and tighten the screw until the lever just begins to move. Turn the screw a quarter-turn more and refit the tamperproof lock.
11. Adjust the throttle, kick-down and cruise-control cables (where applicable).

Injection-system trouble-shooting guide here - https://www.beemerlab.org/2020/12/bmw-bosch-fuel-injection-system-trouble.html

Bosch L-Jetronic injection-system overview / diagram here - https://www.beemerlab.org/2019/11/e30e28e34-bosch-l-jetronic-fuel.html

BMW E21 / E30 323i Engine Comparison [M20b23 2316cc]

Here's another quick engine comparison, this time the E21 and original E30 flagship models, the 323i. BMW introduced the E30 323i in 1983 using the same M20b23 2316cc injected 6-cylinder motor as the E21 had in its top model since 1977 and displacement was not increased until the better known 325i emerged in 1985. Even with sightly more weight, the E30 323i was still billed as a quicker car than its predecessor, but I have no idea what improvements were made to the engine, so lets see how the specs stack up:

M20 Engine	323i [E21]		323i [E30 <1987]
Bore	80.0mm (3.15")		80.0mm (3.15")
Stroke	76.8mm (3.02")		76.8mm (3.02")
Capacity	2316cc (141.3 cu in)		2316cc (141.3 cu in)
Comp. ratio	9.5 : 1		9.8 : 1
Power (BHP)	141 @ 5800rpm		148 @ 6000rpm
Power (PS)	142.8 @ 5800rpm		150.0 @ 6000rpm
Power (KW)	105 @ 5800rpm		110 @ 6000rpm
Torque (Lbs ft)	140 @ 4600rpm		151 @ 4000rpm
Torque (Nm)	190 @ 4600rpm		205 @ 4000rpm

A little more compression, along with a few extra horse power and a slightly higher redline make for a harder pulling engine in the high rev range, but the big difference seems to be in the torque figures. Not only does the E30 323i have a bit more, but peak-torque is delivered 600rpm lower down than the older engine and that is clearly what makes the E30 feel quicker.

E21/E12/E28: Bosch K-Jetronic Fuel Injection System Diagram / Explanation

Two types of fuel injection system are fitted. E21 3er 323i models are equipped with the Bosch K-Jetronic system, whereas E30 3er 320i and 325i models are fitted with the Bosch L-Jetronic system. This article covers K-Jetronic injection for E21 models, also injected E12 and early E28 5er. For L-Jetronic in E30 models, also later injected E28 5er, see THIS ARTICLE.

K-Jetronic Operation:
Fuel is drawn from the fuel tank by an electrically-operated pump and is then fed, via a pressure reservoir and filter unit, to the fuel distributor-unit. The fuel is then pumped direct to the fuel injectors which are located near the inlet valves, but mounted in four induction-manifold branches. The system is continuous acting type and the amount of fuel admitted to the injectors, by the fuel distributor, is governed by a pivoting baffle-plate mounted in the air-intake. Air drawn into the engine lifts the baffle-plate and this action moves a metering shuffle-valve in the fuel distributor. The ratio of air to fuel is thus controlled to a fine degree. After the mixture is drawn into the cylinder, the normal four-stroke combustion cycle takes place.

The fuel is maintained at a constant pressure by a pressure-regulator incorporated into the fuel distributor-unit, excess fuel being diverted through a return-line back to the fuel tank.

For cold starting, a solenoid valve injects fuel into the air-intake for a period determined by the coolant temperature. In addition, a temperature sensitive (warm-up) regulator, working in conjunction with an additional air slide-valve, is connected to the fuel distributor-unit and has the effect of increasing the amount of fuel delivered by the injectors. Later models are fitted with a throttle bypass-valve in place of the additional air slide-valve. On some specific versions this valve is coolant-heated.

A normal type throttle butterfly-valve, mounted between the baffle-plate and the cylinders, is connected to the accelerator pedal linkage. These constant flow injection systems work in a similar manner to a carburettor, vaporising fuel in the inlet-manifold and metering it into the engine.

E30/E28/E34: Bosch L-Jetronic Fuel Injection System Diagram / Explanation

Two types of fuel injection system are fitted. E21 3er 323i models are equipped with the Bosch K-Jetronic system, whereas E30 3er 320i and 325i models are fitted with the Bosch L-Jetronic system. This article covers L-Jetronic injection for E30 models, also later injected E28 and early E34 5er  For K-Jetronic in E21 models, also injected E12 and early E28 5er, see THIS ARTICLE.

K-Jetronic Operation:
In fuel injection systems of Bosch L-Jetronic type, the volume of air drawn in by the engine is measured.

Each cylinder has its own independent injector.

An additional air slide-valve bypasses the throttle butterfly stub pipe and controls the additional air volume required when the air is still cold. When the engine is warm, idle speed airflow control is by means of another bypass around the throttle butterfly.

Fuel supply and pressure is provided by an electric pump with an inline filter and pressure regulator.

The volume of air drawn into the engine is measured by the air flow meter and this is converted into an electric impulse and transmitted to the control unit. A calculation is made to determine the quantity of fuel to be injected (based upon the engine running speed) into each cylinder.

Automatic cold-start and warm up devices are incorporated into the system with corrections made to the amount of fuel delivered for idle-speed and full-load by contacts in the throttle butterfly switch. When the engine is on the overrun and throttle is closed, due delivery is shut off completely.

The electronic control unit processes information from the various engine sensors and sends an impulse to the electromagnetic fuel injectors, telling them to open for a precisely defined period and deliver a set amount of fuel for each ignition. This is how most modern fuel-injection systems (with the exception of direct-injection systems) work.

E21: Steering Wheel Retrofit Guide

I got asked on eBay UK if my E21 steering wheel would actually fit an E30, which it turns out they don't. The wheel was then snapped up by someone with an early '70s 2002, but only after I could convince them it would fit...

It's not straight forward, so to clarify...

Later E30/E36/E46 3-Ser / E28/E34/E39 5-Ser / E24 6-Ser Etc. Steering-Wheel to E21 + other Classic BMW:

To fit later model steering-wheels with the modern spline to your E21 or other pre-'82 BMW, then you will need a steering 'boss' adapter, which bolts to the steering-column and usually has multiple sets of bolt-holes to accept any after-market steering-wheel. Some may only have holes to fit the brand of steering-wheel that make the hub, such as the MOMO one, here for about £60, but could be easily adapted to fit whatever wheel you have. Getting a universal one is harder, sites like meanmachines.biz claim to have ones here for £25 that fit, but they may need adapting to go on the E21.

Earlier E6 [1602/2002] / E12 5-Ser Steering-Wheel to E21:

Not sure why you want the thin, bendy rim of the older model steering-wheels to noon your E21 around, but they are a straight fit and require no modification to the wheel or dash/trim. The horn contact ring at the back needs modifying to work - refer to step 3 of the guide below.


E21 Steering-Wheel to E6 [1602/2002] and E12 5-Ser:

This is a common mod and it makes sense to upgrade 60s and 70s BMWs with the old-style steering wheels to E21 types - they're newer in design, better to use and safer in an accident. E21 wheels are a straight fit to the spline, but some cutting it required to the dash or back of the wheel to get it to fit. The horn button-contact at the back also needs modification.The definitive guide on tidily retrofitting E21 wheels to 2002 etc. is on the 'Bay Area '02' club site- http://www.bayarea02.com/techtips/320_wheel/index.html

The are highlights taken from the bayarea02 guide:
Spline Fitment:
If you place the 320i 4-spoke steering wheel onto the '02 steering column, you'll find that the bottom portion of the steering wheel interferes with the padding on the steering column by about a 1/4 inch. Grab a sharp utility knife and carefully trim away the bottom of the steering wheel, or install some sort of 1/4-inch thick spacer between the steering wheel and the steering column.

If you choose the spacer approach, you have to make your own spacer, as commercial flat washers are too large. The spacer needs to have an inner diameter of about 5/8 inch and can be no larger than 1 inch. When I installed a 320is steering wheel into my '02, I made the spacer out of a piece of 1/8-inch diameter aluminum rod and bent it into a ring using one of the sockets from my toolbox as a mandrel.

One cautionary note about the use of a spacer: The lock nut might not grip the shaft threads if the spacer is too thick. Losing a steering wheel in mid-apex is BAD!

Horn Buttons:

Take a sharp utility knife, and make a radial cut completely through the brass ring on the 320i steering wheel. Once the ring is split, use pliers to carefully bend up one end of the ring high enough to form a cantilever leaf spring. Then bend the tip of the ring over to form a smooth contact surface for the steering column.

This method works well with the standard 4-spoke 320i steering wheel because there is little, if any, access to the internal wires going to the horn buttons.

The classic BMW parts market is a lucrative one, as I will detail my own exploits in another post. I assumed E30 steering-wheels where fair game for the E21 and at the time I listed mine the going rate for an E30 foam-plastic wheel was £30. I got £50 for my original E21 wheel, but I wonder if I could have got more. Due to the scarcity of E21s, I would estimate the value of the basic 4-spoke steering-wheels at minimum £50. The 3-spoke 'sport' wheel in foam-plastic is even more sought after and should fetch up to £100 in good condition and at least £100 for a leather-bound one. The wheel fitted to me E21 was a period AC Schnitzer 3-spoke leather wheel with a removable centre. The boss-adapter and condition of the wheel led me to believe this had been pulled from an E30, though I've never seen another like it and wish I'd put the original one back on to sell the car.

E21: Seat Fitment Guide:

Swapping seats round in a BMW E21 3-series is a nightmare, thanks to the floor-mounts being two different heights. To fit level-based seats from another car requires chopping out the welded floor-mounts and once this is done there is no going back.

1. Check if your floor-mounts have been chopped:

Check the outer floor-mounts on either side, spot-welded in place just inside the door-sill. They should look the one in the left photo below.

If they don't, and they look more like the right photo [with or without the wood], then you have chopped mounts and seats not originally from an E21. You also won't be going back to E21 seats very easily, so to preserve the style and make the ride a lot better, throw in seats from a newer BMW.

2.1 Fitting stock BMW seats from E30, E36 etc. :

This makes sense. E21 seats are sprung and uncomfortable and were dropped in almost every succeeding model. Other BMW seats are easier to come by and cheaper. E30 seats preserve the look almost identically and are far superior in construct. They also fit the inner seat mounts on the E21, the ones against the trans.-tunnel, so only the only outer ones need adapting. I am sure this is the case with seats from other 80s BMWs, possibly the E36 and E46 as I've seen it done, but need confirmation.
Modifying the outer floor-mounts, the ones against the door sills, is impossible as they just sit that much higher than the inner ones, the E21 of course having a crazy odd-height sub-frame design, so they need cutting out. Putting in new ones is pretty straight forward though, you can fabricate them with steel or alloy C-channel, wooden blocks, improvised stilts - these are all popular methods. Tilt-forward seats don't tend to be very strong anyway, so the new mounts don't have to be rock solid as long as they're bolted or welded securely to the floor-pan. Mine used the stock inner floor-mounts and a wooden block on the outer side to get the height - this presented no problem to the UK MOT (roadworthiness-test).

Check out my guide here: http://e21dub.blogspot.co.uk/2013/09/e30-sports-seats-fitted.html

Or check out HSVTurbo's guide HERE [where I got my idea] in THIS THREAD on bimmerforums.

2.2 Fitting rigid Racing bucket-seats:

If you're building a track car then it's obviously best to keep things as stiff and secure as possible. The neatest and most weight-saving method is to cut some steel cross-beams to fit and weld them across the floor-pan, from the trans.-tunnel to the door-sill. This could be done with or without removing the outer floor-mount, but you will probably have to do this to get the seat low enough. Two cross-beams under each seat would probably be best, but it is most often done with just reasonably thick one.

More info. HERE on bimmerforums.

2.3 Fitting non-BMW stock seats (VW, Ford Recaro etc.) :

To get the right height and a central-position with stock seats from non-BMWs there is a lot of modification to the mounts - these seats will always have the bolt-holes in the wrong place. The tidiest way would probably be to weld in rigid cross-beams like in the above guide [2.2], otherwise you will need to fabricate custom mounts. [I used a combination of wood-block and steel cross-beam to fit Ford RS Recaros to mine in THIS POST].

Check out my guide here: http://e21dub.blogspot.co.uk/2013/08/recaro-seat-base-adapter-finally-solved.html

3. Re-fitting stock E21 seats:

I have never seen anyone online do this. If you have level floor-mounts then I see no reason to switch back to E21 seats. All but the Recaros are uncomfortable, sprung nightmares. They give a truly bouncy and uncertain ride - only the most restoration mad would want it. The Recaros are super-rare and overpriced to fit the E21s mounts. E30 Recaros are a fraction of the price, have level mounts and are better anyway. If you are so desperate to restore your E21 dutifully, then I would consider it having cut floor-mounts a deal-breaker and to find one with stock seats, because the car will never be the same again.

There are 3 ways I see to achieve refitting stock seats:

1. Build custom outer mounts using a combination of the methods above, building them back up to the original and rather tall height for the stock seat-frames. [].

2. Locate a pair of original outer floor-mounts that have been cut out of another E21 and refit them to yours. These would first need to have been cut out carefully from the donor car and preserved by someone. Whether they would advertise them for sale is another matter, but asking on the forums can't hurt. Otherwise, you'll need to find someone with a scrap / breaking E21 and ask to neatly cut out its floor-mounts for a few quid. Either way, obtaining a useable pair is going to be tough.
Once you do though, they would just need to be measured up to where yours were cut off and welded into place. How neat a job you do will determine whether they fit or if it's unnoticeable.

3. Fabricate new outer mounts from the ground up out of steel and weld those in. I will endeavour to make a note of the dimensions of my cut one before passing it on and do a quick CAD design to fab-up a simple one.

**Also, I still have the passenger-side (N/S, Euro/US Driver-side) floor-mount [above], so if anyone wants it to try and weld back in message me! [Sadly, I cut the driver-side one out more severely and this is probably going to be the case if yours are chopped as it gives the wood or whatever more to grab on to.]

E21: Deep 'Alpina' Style Front Valance on eBay UK

** UPDATE - This sold for the same £51 bid that was there on day one of the auction, but alas I missed the end.

I've been looking for a replacement chrome rear-bumper to get rid of the two minor, but ugly, dents on mine and spotted this -

http://www.ebay.co.uk/itm/121179262087?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

A super-rare for the UK deep front-valance / bumper, I think from the 'Alpina' models and it's genuine BMW. Probably going to sell for way over the current £50 bid, but I think I will be having a cheeky bid myself if it doesn't go stratospheric.

E21: Front indicators - a common problem?

Is your front corner-indicator not working, but the bulb and fuse are fine?

Mine wasn't and it turned out to be the metal live-clip that sits against the bottom of the bulb. Not the best of designs, connection is lost to the bulb if the clip is bent back slightly, causing the indicator to fail intermittently [denoted by faster clicking of the turning-signal]. The clip having a little corrosion or crud on it is also enough to stop the bulb getting a signal.

A quick clean up with emery-cloth and a slight bend forwards so it sits tight on the bulb was enough to get mine working solidly again. This could be a common problem, especially in the UK and Europe where grime gets pushed everywhere in an E21, so if your fuse and bulb appear fine, but the indicator won't work, you can bet it's the live-clip.

PROCESS:

1. Dis-connect the corner indicator wiring by sliding apart the plastic-clip located behind the headlamp under the bonnet and push it through the hole to the outside of the wing.

2. Remove the two crosshead screws holding the corner-indicator lens and lift the lens off.

3. Remove the two crosshead screws holding the indicator-housing to the wing. The housing should now slide forwards and clear the wing.

4. Use nose-pliers to remove the metal live-clip from where it sits in the plastic-housing.

5. Bend the prong [denoted by the arrow] in towards the other prong, bringing the flat-edge down.

6. Clean up the face of the prong and the metal-contact on the bulb with emery-cloth.

7. Replace the live-clip to the plastic-housing and reverse Steps 1-3 to re-fit.

E21: HOW-TO - Stereo Head-Unit Retrofit / Wiring Diagram

I had noticed a few electrical gremlins since fitting the modern stereo and have finally figured out the slight wiring difference between the 316 and the 320, the latter of which is shown in the E21 Wiring Diagrams available on the internet [download here]. Thought I'd throw up an updated diagram of how the wiring can be correctly adapted in the base model E21s.

Basically if the car had a stereo available as an option, which only the higher models did, then the two power wires necessary for a modern stereo are present. On base models [315, 316, 318], only a single aux. power wire is present. It can be made to run a stereo head-unit, but there are problems so if you're thinking of doing this it's worth reading my failsafe guide.

As in the diagram above, a modern radio/CD-player type head-unit will most likely require two power sources. A red wire connected directly to the battery that supplies a small amount of power to save settings and CD positions, and a yellow wire connected to the ignition switch that tells it to only turn on when the car is fired up. *Connecting both wires straight to the battery is an option so the unit can be used with the ignition off, but this will mean a higher drain to the battery and obviously has the potential to be left on by accident.

GUIDE:

At the back of the centre-console somewhere will be a chunky black wiring-connector, referred to as C40 in the diagram above, with 4 prongs and five wires joining either side. Two brown/violet wires from fuses 17 and 18 join at C40 and become a single wire - this is the best source for ignition power. The single brown/violet wire goes to a small 2-prong connector, which shouldn't have anything plugged into it, so connect the yellow wire here. The larger brown earth-wire on the connector goes back to C40 and grounds with the rest of the instruments and interior lights at G49, somewhere to the left hand side of the passenger side footwell. This is an ideal place to ground the black earth-wire from the head-unit, but modern stereos draw a lot of current and it might be worth running the black wire to a new earth-point on the centre-console bracket, as in the diagram above.

The only source in the dashboard connected directly to the battery is the cig. lighter circuit on Fuse 16 and has no spare connector so a wire must be spliced somehow into the red/yellow wire running through connector C40 - I just used a Scotch-block type crimp-connector. This new wire should be connected to the red wire on the head-unit.

To connect the relevant prongs on the head-unit wiring-connector I used short pieces of wire with female spade crimp-connectors. At the other ends are male spade-connectors to fit into the brown/violet wire-connector and similar connectors for the speakers, though I simply cut these off my speaker-wires and connected them straight to the head-unit connector with female spade-connectors.

Unlike the diagram above, 315/6/8 models should have green [pos.] + green/black [neg.] wires for the left-hand speaker and grey [pos.] + grey/black [neg.] wires for the right, to be attached to the corresponding prongs on the head-unit connector. These models should also have no rear speakers, unless they have been added on and will have a range of wiring colours.

Unless your planning on hiding your head-unit away somewhere, which I was originally, then you will need a fascia-adapter. They're not common, but can still be bought new from BMW or BMW Classic or one might come up on eBay, but I haven't found a spurious one yet. I was lucky to be given one with the car, still sealed in its bag. I intended not to use it and stash the head-unit in the glove-box or beneath a flap as security isn't great in the E21s, but I must admit it does look smart.

If a constant live connection to the battery is not something you want or your cig. lighter socket is already running a high-power device, then the simplest method is to just power both the red and yellow wires from the single brown/violet wire terminal [pic below]. This works just fine in powering up the head-unit, but the memory-power is turned off with the ignition and it won't save your settings or jump back to where a CD was previously playing. 

It will also be drawing the full amperage through the rev. counter circuit, Fuse 17. This shouldn't cause a problem in theory, as the same terminal on connector C40 has a more direct route to ign. power, the other brown/violet wire from Fuse 18, but it still caused a problem for me after a week or two when the rev. counter/clock unit began to trip out and stop power to the radio and instrument lights somehow. Neither fuse would blow, but power would not return to anything on that circuit until both fuse 17 and 18 had been pulled out and re-inserted with the ignition turned on. You may get away with an extra or shorter earth wire, rather than the radio/rev. counter circuit grounding at G49 with the rest of the dashboard etc., but run this setup with caution.

Is the E21 3 Series worth saving??

Nice bit of blurb about the E21 from 2008 on Pistonheads.com, surprisingly at the top of an advert for a Henna Red 316 in the 'Shed Of The Week' section... lol!

Before Chris Bangle came along, BMW styling was simple. Whatever the size or intended market, you'd give it a well-balanced three-box profile, a thrusting shark nose complete with kidney grille, add in the trademark 'Hofmeister kink' on the C-pillar, then put the pen down, with the satisfaction of a job well done. No flame surfacing, no controversial rumps, just variations on an 'if it ain't broke then don't fix it' theme.

The first 3-series - the E21 - was the epitome of this styling approach. And it worked, too. During the course of the first 3-series' production run between 1975 and 1983, BMW factories in Germany, South Africa and Egypt churned out more than 1.3-million E21s, making it the best-selling BMW in history.

In doing so, the smallest BMW helped to define an entire class of car - the compact executive saloon. Now, junior and middle management types could afford a classy, sporty car that looked just like their boss's 5-series.

As you'd expect in a small BMW saloon, the neutral handling, rear-wheel drive, faithful steering and light weight make the E21 a car with track-shed potential, especially if you can find one of the later, fuel injected six-cylinder models.

Full thread here: http://www.pistonheads.com/gassing/topic.asp?t=754821

A lot of people on there panning the four cylinder model E21s, saying only the sixes are worth preserving as classics. I'd have to disagree with this. There are so few E21s still left on the road in Britain, where rust and rot are magnified by 10, that surely they're all worth keeping. 1.3 million E21s may have been produced, but in the UK they were massively overpriced compared to their British Leyland or Japanese counterparts, all of which came with heaps more trim than the BMW and this meant they never really sold that well here in the first place, the E30 becoming a much more common sight in the 1980s. Never the less, Morris Marinas and MGBs, both using the same BL 1800cc lump, are cherished, restored and no one could suggest they be broken up to save one scrapped hot model like a B V8, and who is to say the genre-defining E21 is any less significant or rare?
A 323i for instance is faster than the 316 for sure, but it would get beaten to a pulp by a modern 320d and besides, in a 30+ year old car how fast can it really go? Components are going to be worn and if the car is truly well looked after is it worth pushing it to the limit? Ok, so there are going to be people buying E21s that are destined for the track, but a classic car will need serious modifications for this and when the chassis and brakes have been done is the ancient M20 323i lump going to feel so fast? The real way to make a go-fast E21 is to swap in a modern injected BMW engine. M42 (316/8i) and M43 (318is) engines from the E36 will drop straight in without any modifications to the engine bay and these 4-cylinders will already be keeping up with the six-cyl originals - they'll also be more reliable and a lot easier to find bits for like injectors, ahem. By this point though, you no longer have an original classic and that's the true essence of preserving a car this old.
Who cares if it won't melt tyres when it looks this good? E21s are all about keeping alive the shark-nose BMW tradition that began to fade away with the E30. The quad headlights from the 3.0CSL also became a mainstay on the E21 and brought with it the transition into the meaner looking BMW's of the '80s, most notably the E24 6-series and E28 saloon. Before this were the much softer, European looking models with two large bug-eyed headlights, like the gorgeous 2002 and original E12 5-series. The 315/6/8 E21 hark back to these historic models, where the sixes heralded the sporty future and boy-racer image that bound the marque from there on. This, arguably, makes the single headlight E21 models the prettier car and even more worthy of preserving with the '70s models, as true BMW classics.