b35 Crankshaft

[decoupe]

Where can I find or can someone supply the specs and tolerances of a crankshaft from a 1990 535i. Need to check if one I have found can be used in my m90 block to up the displacement to 3.7 litres.

The attached quote from a X_atlas post (thanks) gives a background to the question.

Thanks

I've been looking for the last few days over dicussions about the M30 and M90 engines. (bimmerforums, bigcoupegroup, firstfives, the lot of them) I've been attempting to determine which would work best for a twin-screw kit I've been cooking up.

As far as I can tell, the M90, being significantly oversquare, makes more low-end torque, but dies above 5k or so due to head design.

The M30, however, being a significantly more square engine, (in B35 trim) means it had more even torque over the RPM spread and started to croak at abut 5500 RPM, although I haven't been able to tell if that is because of the larger valves or the displacement setup.

I know the M90 has the advantage of being easily stroked with a M30B35 crank to bring it to ~3.650L, but it also has the disadvantage of head upgrade restrictions and the use of a distributor, whereas the M30 has the later "distributorless" Motronic 1.3 setup and larger valves later in life.

Given how the M90 is based off the M88, I also don't know if the M88 head (not the S38 head) is a bolt-on affair. If it is, that is a very significant advantage to a M90-based engine.

So any other pros/cons between the M30B35 and the M90?

 

[x_atlas0]

What kind of specs are you looking for? Crank journal concentricity, cylindricity, profile tolerance, hardness, that kind of thing, or something more basic like stroke?

As far as I know, all M30 cranks are interchangeable, as long as they are paired with bearings to match the crank.

 

[sfdon]

The M90 crank was notorious for poor quality - piston height at the deck was all over the place.
Keep in mind the M90 is not about the head- it's the bore and the compression.

 

[Nicad]

What kind of specs are you looking for? Crank journal concentricity, cylindricity, profile tolerance, hardness, that kind of thing, or something more basic like stroke?

As far as I know, all M30 cranks are interchangeable, as long as they are paired with bearings to match the crank.

I know from experience a 733i crank does not fit in a 1972 3.0 cs block.

 

[DerSchwede]

I know from experience a 733i crank does not fit in a 1972 3.0 cs block.

But the 86 mm L-jet/Motronic crank and the 88,9 mm 3.3L (carbed) crank fit the 3.0 engines from 1974 and on - look for the 3.0/3.3 marking on the water channel below the carbs.

 

[decoupe]

What kind of specs are you looking for? Crank journal concentricity, cylindricity, profile tolerance, hardness, that kind of thing, or something more basic like stroke?

As far as I know, all M30 cranks are interchangeable, as long as they are paired with bearings to match the crank.

I guess what I'm looking for is what should I measure (and what are the specs) to see if this crank is worn to the point of being unacceptable - came from a decent running rust bucket of a car. This would be done by a machine shop but they aren't specialists in these engines (there aren't any in Calgary).

Or is this just something a good shop can determine without the factory specs?

Thanks

 

[sfdon]

I believe I copied that info off my German microfiche years ago,
It also could be in the specification appendix of the factory repair manual cd.
I can check next week when I get home.

 

[sfdon]

Ok - I think found it.
10 years ok I copied from microfiche. All my libraries of factory info are hosted by Scottie Sharpe. Be careful what you download- there are thousands of pages.
I think you want this file:


File Library
File Library » Factory Technical Manuals
Search for...
Select File Categories:

M30 Engine Specs
ADD an item to the library!
File Information
Title: M30 Engine Specs
File Version:
Post Date: Jan 26 2003
Post Date: 81 745i
84 745i
82 745i
83 745i
85 745i
86 745i
80 745i
Difficulty: Normal
Author: BMW
File: Download Now
Readme Included: Yes
Discussion: Topic Link
Rating: Not yet rated

Downloads: 430
Description
M30 Engine Specifications masterfully scanned by Don. Engine building clearances for the M30 motor. Plus other valuable specifications for the wonderful six.

You need to go to : http://bmwturbos.scottiesharpe.com
After login you go to resources then file library and then factory technical manuals
If you can't login- contact me and I will share my password with you.

There is another file that would have the info I think too- look for :


M102 Factory Repair Manual Author: BMW
Downloaded: 597 Added: Jan 21 2003 Read reviews | Opinar/Avaliar | Rated:
Engine manual scans from the expansive Lawrence library... About 3.5 mb


Good luck

 

[decoupe]

Gulp....

Thanks Don ... back to school time for me.

 

[DerSchwede]

Thanks Don ... back to school time for me.

If you have access to the blue BMW manuals, it's all in there.

 

[x_atlas0]

I know from experience a 733i crank does not fit in a 1972 3.0 cs block.

What didn't fit? I'd like to know.