Bottom's up M20B27 e2i Build

[cek]

That is pretty neat and represents a lot of work. When you get this finished I'd like to add a reference to it in the "Diagnostics, tips, & tricks by Jim Levie (E30 Jedi Master)" in the FAQ & DIY section. A PDF would probably be ideal and if you will email me a copy I'll add a notice that members could PM you or myself for an email delivered copy.

FYI: The Bentley and ETK shows five main bearing "colors" and slightly different numbers for the journal sizes for each "color".

Yeah, I just saw that in Bentley. On page 5-17 (E28) it reads "On 528e models, double classification replacement bearings are no longer available from BMW. The triple classification bearings (yellow, green, and white) can be used in engines with double classification bearings. Replace red bearings with yellow bearings and blue bearings with green bearings."

I've updated the sheet to include yellow, green, and white for Standard size. I'll do the undersize one's later.

[cek]

Question about piston ring side clearance:

The main ring side clearance spec is 0.0028". I can get a 0.0030" feeler in there. What's worn, the rings or the piston? Or is this close enough?

I've searched and found no (!) discussions on piston ring side clearance...

[cek]

Mostly done measuring things...



There's almost no conicity (taper) on this block.

The bores are also almost round; well within spec.

It wore very uniformly. At ~0.0028" cylinder to piston clearance I could slap this back together and still be way within max (0.0047").

Kinda mind-blowing for a 360k block. The pistons account for much of the wear.

Crank bearings are worn. Connecting rod bearing diameter is 1.7705-1.7709" with minimum spec being 1.7707".

Main bearing diameters are 2.3609-2.3613" with minimum spec being 2.3614".

Of course, it could be ground down to next size. But I have another crank incoming anyway.

I did not use plastiguage to measure the radial clearances. Out of time for today. But I plan on doing it for the main bearings and caps sometime soon just to get the experience. Never used platsigauge before...

[cek]

Two 325i M20 throttle bodies. One has a broken spring holder. They have different vacuum attachment thingies. I'm wondering which one will be the right one to use.


Oil pump cleaned (mostly). Gears show no wear.


Cleaned up a bunch of other parts today too.

Hopefully I'll be able to pick up the 'new' block and crankshaft this week.

[TobyB]

Gears show no wear

and the housing doesn't show any scoring at all- which is even more impressive... if the bottom
plate's smooth, that's a new pump.

As to ring end gap, yes, it's good to check. I only do on race motors, or where I
am not familiar with the ring vendor.

Side clearance should be minimal- this is why I usually buy new pistons. When it gets
much over the maximum allowed, the ring starts to twist back and forth in the gap,
wear escalates, and then the ring breaks in pretty quick order. I've had it happen with 2
M10's- the first was an unknown shortblock, but the second was only at the max clearance
when I re- ringed it, and it lasted exactly 2 lapping seasons before it ventilated a
piston.

hth

t

[cek]

and the housing doesn't show any scoring at all- which is even more impressive... if the bottom
plate's smooth, that's a new pump.

I doubt the pump is new. It was extremely encrusted. Also, see the plate:


It's got some wear on it. Doesn't seem like much, but what do I know?

[cek]

Can one use main bearing caps from one block in another?

I just realized the block I bought didn't come with the caps.

I have a set from my other block.

In test fitting them, they don't appear to fit.



Are they supposed to be a tight fit? I mean it looks like it will take quite some force to get them in.

And, of course, because I was focused on the block, I bought "old style" bearings, and the caps I have are "new style".



Blarg.

[cek]

Recall my goal has been to build an e2i ‘stroker’ that COULD have FI added later. This build is really just an exercise in getting engine building experience, plus the oppt to dive into FI eventually.

Recap:

- M20B25 block
- M20B27 Super-ETA Pistons (domed)
- 130mm rods (“Max Speeding Pro I-beam”)
- M20B27 crank
- 885 Head
- 8.5:1 comp

I’m at the point of needing to select a head gasket. Should go for a high-end (MLS) HG, or is a standard one ok?

Other than drilling/tapping for the oil return and putting engine bay insulation in, what else shoudl I do be prepared for future FI while there’s no engine in the car (without actually doing all that shit)?

I decided to see if I could find ANOTHER block and came across a 325i motor & 5-speed on CL. Claimed 100k miles. Price was right AND the kid agreed to deliver it to my house (that's twice I've been surprised by CL sellers saying yes when I asked if they could deliver the item!).


It certainly appears to be a low mileage M20B25 as advertised. Tons of cross hatching on cylinder walls and the 885 head looks super clean; no real wear visible/felt on the camshaft. Turns really smoothly.



.0047" is the max cylinder to piston clearance. The other blocks were > .0030 to .0045". This one is .0026" at worst.


Bore is supposed to be 3.3071". Side-to-side, mid way down bore #3 is 3.373". Nice.


It'll almost be a shame to hone it.


Last weekend I cleaned and prepped and painted the block. I had another can of silver engine paint, this time less sparkley, and used that. I also installed new freeze plugs.



This week I dove into honing with the Flexhone tool I bought. Never done it before so was a bit nervous, but a few Youtube videos later I gained confidence. I did a trial run on the OTHER block just to get practice. It is a messy proceedure with oil flying everywhere, but super easy to do once you get started.

Here's what the 'new' block looked like before:


Here's after:



All ready for bearings now...



Achievement unlocked: Successfully used Plastigage.


Crank to bearing clearance is tits.


Bottom half of the bottom half is done! Turns super smooth. I'm not really sure what it's supposed to feel like, but I'm pretty sure it feels right.


I took extra, extra care to make sure everything was surgically clean. I carefully inspected the crank and the bearings for any burs, scratches or foreign material. I also double checked the journals in the crank were clean.

Got all the pistons and rods prepped. New rings. Sexy 130mm I-beam "MaxSpeed" rods.



Cleaned up the 885 head.


If you like watching paint dry, you can watch me do all of the above in this timelapse: https://youtu.be/QCqzonV3KXo

Then I got the bottom-end all together. I have not torqued the rod bolts because the MaxSpeed rods didn't come with instructions and I can't find the torque specs anywhere for them on the 'net. I emailed customer support, but they are in #Brexit.




I should have done this before, but since i'm eventually going to turbo this motor, I want to tap the block for the oil return now and cap it. I'm trying to determine the optimal location. Ideas?

[cek]

A bunch of updates incoming.... this project was moving very slowly with some back and forths, but is now ALMOST done.

Using these instructions, I rebuilt some injectors.

http://twrite.org/shogunnew/files/fontes/Injector_Rebuild.pdf

Purchased this kit: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1





Pretty clear how injectors can get clogged over time... Look at that grimy old filter...


I *could* paint them, but nah.

[cek]

I'm not sure I mentioned this above, but I changed plans on this motor. I'm no longer going to blow it (pun intended). Instead it's now 40-over and 9.5:1 compression.

Assembly:.

[cek]

Moar assembly. Plus some test fitting to see what parts I'm missing or forgot about. Discovered I'm missing the dowel pin for the camshaft timing belt sprocket and a locator dowel for the timing belt cover to head.

[cek]

A big gift box from Blunt:



And a shipment from Cometic with an MLS head gasket that was specified by the machinist. With this, do believe I have all the parts required to finish assembly (and more).

The machinist apparently didn't chase the threads for the head studs, so I took care of that. Given what I paid him, i'm a little disappointed he didn't do it.


.86" thick, with .86mm bore. Easy to remember.

[cek]

Got the oil pump in and pan on.



Stated putting the timing components on then realized that I didn't really know what I was doing. :shock: Then I ran out of time.



I gotta mount the timing belt sprocket to the head (I was missing the locating dowel; it came from Blunt) and turn the camshaft to get the head aligned for TDC. Right now I have it just sitting there in an orientation where all the pistons are out of the way.

But it's looking more and more like an engine.

[cek]

To most of you this must feel like you're watching paint dry. But trust me, I'm making progress. I'm trying to be super careful and meticulous.





Head is on. Studs torqued. Valves adjusted.

I spent a lot of time test fitting vacuum, fuel, etc... hoses and wires. Found more parts I'm missing. Not sure how that could be because I kept everything from 2+ motors. But alas...

[cek]

This is frustrating.

In starting this project I acquired the following:

- An 88 528e that I parted out.
- An engine from an E30 325e
- An engine from an E30 325i

In all this, I failed to notice that none of these engines came with a 325i intake boot and associated hoses. Both of the intake boots (including the one I dutifully cleaned) I have are from Seta motors (the 528e and 325e) and as a result only fit the SMALLER Seta throttle body, not the larger 325i body.

The weird thing is I have THREE larger throttle bodies and only one smaller one. I simply don't remember how all this happened.

The upshot is I'm missing a bunch of parts.

For reference I took a picture of my buddy's 325ix engine bay. I'm missing everything circled.



I think older 325i had a simpler setup without the dual check valve for the brake booster, but I've been unable to verify this. Most online diagrams are ambiguous.