E21 320 - Using 2002 Transmission for conversion

[Paris]

Hi all,

I own an automatic 320. a 1977 model.

I drive it every day, it has been great.

I am now faced with an issue, cylinder 1 is down on compression and it is blowing smoke, the motor requires an overhaul. It has over 300,000km's on it, what do you expect from such milage.

It is a single Solex Carburetted car, it's not fast, but it starts easy and is very easy to drive.

One thing i've always wanted is for it to be manual, the automatic really doesn't give the car justice (It's sitting on coilovers and handles like a dream), so as part of making a new motor for it, I require a list of parts I need to obtain.

I have two 2 litre 4 speed 2002 complete cars that are too rusty to rescue that I can borrow parts from.

So, first up, building a hot M10... I use an E12 head... can I use a 2002 bottom end? Should I use my E21 head? Should I have the head ported, do they need hardened valve seats for unleaded petrol? Which carburetors should I use? What works best?

Gearboxes... Can I use the 4 speed from the M10 powered 2002's, do they have the required speedo drive? Can I use the 2002 prop shaft? Can I use the 2002 gear end, or are the E21 auto differential ratios OK?

Where do I grab a pedal/clutch assembly from? Are they hydraulic or cable? Are the required holes and mounting points in the E21 firewall already? Can I use 2002 parts or do I require E21 parts? Can I use M20 E21 parts?

Where do I can twin carb linkages from? Can I use the single Solex throttle cable?

Thanks

[Jeroen]

Welcome here! Hope to see a little presentation of the car in the Owners Gallery in the near future

A lot of Q's, let me try to make a start. You have a 4 cil 320? As in '77 (at least here) is the changeover year to 6 cylinder.
Also note that you can find a lit of info here as well: http://www.bmwe21.net/?page_id=124

Not all E21 and 2002 heads and bottom end can be mated, need more details but perhaps its even easier to use one of your complete 2002 engines.

What to do with the head depends on your wishes and budget, I believe hardened valve seats are advised, unless you have a later replacement engine as BMW supplied hardened valve seats on all engines produced from 1983 on.

I believe the 02 boxes do fit and they do have the speedo drive indeed. Prop is a different length though. Diff is practically the same, same housing, you just need to fit an E21 diff cover. As for ratios, depends on what you want but perhaps you should just stick tou your current E21 diff? E21 diff ratios are all on our website's specs pages and are the same for manual and auto.

Clutch operation is hydraulic. There is a separate panel (E21 specific) you can swap out when converting to manual that has the correct attachments for the clutch pedal etc. Also see http://bmwfans.info/parts-catalog/E21/J ... ht_switch/ for an example.

Last one from me is a link to another conversion topic in our Top Tech Topics here.