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Posted: **Sat Mar 22, 2014 11:23 am**

Duracel79 wrote:Hi Keith,

I have built a few of these and there are many ways to go.

A Key point is you must use the pistons that match the head. 325 pistons with an 885 head or Eta pistons with a 200 or 731 head.
If this isn't followed you will either have:

ETA pistons with 885 head - Very low compression and possible valve to piston contact - pistons need valve cutouts machining to fix.
325 pistons with 200/731 head - major contact between piston and head - head combustion chambers need machining to replicate the 885 head chamber.

This is assuming the piston height has been corrected in the block.
-------------------------

With the parts you already have, I'm not 100% what the length of the diesel conrods are but if they are 130mm they are useable.
You will need flat top 84mm ETA pistons to run in a 323i (200) head, I'd prefer using a 731 head as the chambers are the same but the ports are much better.

323i block can be bored out to 84mm quite easily. Best way to get a fresh bore rather than a worn 325 block that is not worn over the full stroke of a 2.7.
No need to skim the block down if you get ETA pistons.

I'd recommend a vernier pulley to time up the camshaft and ensure you get the best valve/piston clearance. Especially if you don't know the full spec of the camshaft.

This would are still work well with the std K-Jet if its working properly. There are Warmup regulators which allow adjustment which can help get the best out of the system.
Would help with the increased capacity.

------------------------------------------

Best spec with stock (ish) parts would be

323i block bored to 84mm
Block deck machined down by 1.5 to 2mm
324d crank or ETA balanced
lightened & balanced 323i conrods
Early Pre87 (6E1) 325i pistons (new rings)
885 head lightly ported on the exhaust side
Vernier pulley to correct cam timing and get valve clearance

-----------------------------------

There are other variations such as the Super ETA available in the states which uses 325i style pistons in an 885 head but I doubt they are easy to come by.

Having said all that - If you could afford a set of new Forged pistons they can be specified to suit any head/conrod/block combination possibly giving the best of all worlds but they do come at a price!!

Hope some of this helps

Ben

There is so much advice on how to build one of these but how much of this is correct is difficult to know but Ben's answer seems to be the most comprehensive direct advice I've seen so far.

The 324d crank is allegedly stronger so I'll probably go with that, the 324d rods are allegedly the correct length but I haven't measured them yet, I have the 323 rods I could use anyway. If I can find a pre '87 325 engine will this come with the 885 head and matching pistons?

Posted: **Sat Mar 22, 2014 12:41 pm**

Yes pre 87 325 engine should have and engine code 25 6E1 stamped by the engine number. These will be the early 9.75 CR pistons and an 885 head, unless its been changed at any point ( usually with another 885,number can be found cast in the head just above the inlet ports ). There is a 25 6E2 ( 9.4 CR ) engine that was built for short time over the changeover years and then they made the 25 6K ( 8.8 CR ) engine.

It is possible to use the 325i block from any of these after carefully inspecting it. Needs to still show good factory hone marks and no ridges or increase in diameter at the top of the bores where the original rings get up to.
If the wear is minimal you could get away with a light hone of the bores and get the block machined by 1.5 to 2mm.
Everyone says 1.5 to 2mm because at 1.5 it is safe. With high lift cams the valve to piston clearance on overlap can be very tight at 2mm.
There are also 0.3mm thicker head gaskets available if needed to aid clearance.

You'll need a new set of rings on the 325 pistons no matter what due to the extra fresh bore you will be using at the top/bottom of the bore.
Get new big ends and mains for the 81mm crank after measuring the journals and fit it all with a nice bit of lube.

Expected CR for a 2.7 with 885 head assuming no head skim:

256E1 pistons, 1.5mm block decked, 81mm crank = 9.92 CR
256E1 pistons, 2.0mm block decked, 81mm crank = 10.45 CR

256E2 pistons, 1.5mm block decked, 81mm crank = 9.58 CR
256E2 pistons, 2.0mm block decked, 81mm crank = 10.07 CR

256K pistons, 1.5mm block decked, 81mm crank = 9.00 CR
256K pistons, 2.0mm block decked, 81mm crank = 9.42 CR

Regards

Ben

Posted: **Sat Mar 22, 2014 6:28 pm**

OK, that all sort of makes sense and I have a friend with a '86 engine with 885 head in his garden. Getting near the end of the questions now.

Can I run the '86 325 head/block with the e21 injection system and side mounted distributor as I want it to look stock?

Posted: **Mon Mar 24, 2014 4:28 pm**

Yes the 325i engines have a blanking plug where the dizzy mounts, so easy to fit it in there.

The K-Jet system all fit and bolt up to the engine head. The only diff would be where the WUR (warm up regulator / control pressure valve) is mounted. the 323i has a hole in the block and two studs for the mounting near the dizzy.
The 325i block does not have this. The WUR is also warmed up by the water system so not too much of an issue, just mount it near the area with the required water hoses attached.

I would recommend dremmelling out the K-jet inlet manifold so that is matches the 325i inlet gaskets better. But otherswise it should fit ok.

As for the fuelling side I already mentioned that the control pressure can be played with to increase the fueling.
This may be required with a good 2.7 to get the most out of it. This is where you get an adjustable version of the WUR. Or modify one to be adjustable.
Needs setting up on a RR ideally.

Cheers

Ben

Posted: **Wed Mar 26, 2014 2:57 pm**

Many thanks for all the input.
So the bits I have so far:
885 head with matching pistons,
Pre facelift block
324d Crank and conrods
New camshaft , cant remember what it is but supposed to be the same as a Schrick, have to check
6-branch manifold, not sure if its e21, e28, e34 or e30 so may need to be modified or disgarded,
Vernier timing kit (ebay special)
Adjustable fuel pressure regulator (I have in stock from an e30)

The last remaining part of the puzzle is who to get to do all the machining work (somewhere in the M4 corridor would be great but I can travel) and where to get a set of rings at a not too stupid price!

Posted: **Wed Mar 26, 2014 3:08 pm**

I bought GOETZE piston rings on ebay
http://www.ebay.co.uk/itm/BMW-E28-E30-E ... 3f2254ff0f

the only difference between M20B27 pistons and M20B25 is that the B27 are 1mm thicker.

about this : Vernier timing kit (ebay special)

can you show what you bought? Because mine was for a M20 engine (stated in the ebay add) but wasn't for a M20 (just another ebay scammer).

Posted: **Wed Mar 26, 2014 5:57 pm**

I haven't bought the Vernier kit but was looking at this

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1149450039

Posted: **Wed Mar 26, 2014 9:55 pm**

bought one just like this, only in purple-ish colour, belt didnt fit (the distance between the teeth was wrong).

Posted: **Thu Mar 27, 2014 11:15 am**

Thanks, I'll bare that in mind when I order.

Does anyone have ideas on a company to do the machining work, somewhere in the Thames Valley or South East?

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