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FAQ / REFERENCE => M42 Reference => Topic started by: wannam42 on December 21, 2009, 08:54:41 AM

Title: E36 M42 engine rebuild factory specs?
Post by: wannam42 on December 21, 2009, 08:54:41 AM

I'm planning to do a full rebuild of an M42 from an E36. Does anyone have a list of specs / tolerances for the machine shop to follow?

The E36 Bentley manual lists some but it's for the head and it may not even be complete. I don't have the Haynes.

I've read on this forum that the E36 and E30 M42s do not share the same set of piston rings. I'm not sure what else is different. :confused:

Can anyone help me?

Title: E36 M42 engine rebuild factory specs?
Post by: longtallsally on December 25, 2009, 06:45:56 PM

Ooooh.  I wanna know some of this too as I'd eventually like to rebuild my engine, or swap in one that I've rebuilt.

Title: E36 M42 engine rebuild factory specs?
Post by: BlueBMW on December 26, 2009, 09:41:52 AM

Here's what I've gathered from the technical data I have access to.  This is for an E36 318is coupe with an M42b18 (US Spec of course)  Hope this helps
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/1-1.png)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/2.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/3.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/4.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/5.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/6.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/7.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/8.jpg)
(http://i905.photobucket.com/albums/ac253/bmcdanold/Car%20stuff/9.jpg)

Title: E36 M42 engine rebuild factory specs?
Post by: wannam42 on December 30, 2009, 11:20:24 PM

Many thanks BlueBMW! I can't understand half of it though. :o

What does the +0.014 mean in the bore dimensions?

Did I read it right that valve guides aren't replaceable for the E36 M42?

The conrod bearing journals have a +0.009 and a +0.025 notation. What does this mean?

The piston-to-wall clearance is 0.01 - 0.04mm? That's 0.00039 inches! So what does the 0.15mm max wear clearance between piston and cylinder mean? :confused:

Title: E36 M42 engine rebuild factory specs?
Post by: dwtaylorpdx on December 31, 2009, 12:37:21 AM

They are drilled in place, however a good engine builder can bore them out and put sil-bronze ones in.

Dave

Title: E36 M42 engine rebuild factory specs?
Post by: BlueBMW on December 31, 2009, 06:51:39 AM

From what I can tell those + numbers are tolerances meaning it could be up to that much larger than spec.  I haven't done much engine building so I cant say for sure.  Those are just what I could find in technical documentation.

Title: E36 M42 engine rebuild factory specs?
Post by: wannam42 on January 01, 2010, 11:03:56 PM

No worries, BlueBMW. :)

Interestingly, this is more complete and quite similar to the tech info that cecotto gave in this thread: http://m42club.com/forums/showthread.php?t=1985 (http://m42club.com/forums/showthread.php?t=1985)

It looks like the E36 and E30 clearances are the same.

Title: E36 M42 engine rebuild factory specs?
Post by: wannam42 on January 01, 2010, 11:10:58 PM

I almost forgot. Thanks for the info as well, Dave. :) I'll be sure to ask the machine shop to do this. Not sure if this is really necessary though. What do you think?