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.
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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.
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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
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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?
