Announcement

Collapse
No announcement yet.

M30/M90 Identification

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    M30/M90 Identification

    I am planning on checking out a car that supposedly has a m30 engine and transmission from a 1983 "European" 735i.

    Question is are all European 735i's come with the M90 (shorter stroke & higher compression m30 variant)? What is the best way to identify this motor? I've read that they are suppose to have a 'L' stamped somewhere on the block.

    Heres a pictures of the engine:



    Let me know what you all think. Thanks!

    #2
    Pretty sure M90s onyl come with the log style intake manifold. Mine also has some older style of distribution going on where the rotor and cap is angled 90 degrees from the front of the head, that looks more like an M30 to me.
    86Zinno

    Comment


      #3
      This would be a good start for engine identification:


      As far as I know the "L" block was discontinued after '81 and yes the "L" block would have been an M90 with the log style manifold. That looks like a B34 to me.
      $500, Diamantschwarz, and a Dream

      Comment


        #4
        The seller states the 735 that was imported was an 82 and registered as an 83.

        Comment


          #5
          I forget how to check for a euro engine but you could always run the VIN through RealOEM just to be sure he isn't pulling your leg. The advice I always heard about determining if it is a high-compression euro b34 is to take one of the spark plugs out and feel the top of the piston. The low compression b34 will be dished the high compression b34 will be piano topped. Hope that helps.
          $500, Diamantschwarz, and a Dream

          Comment


            #6
            Originally posted by TurboFox93 View Post
            I am planning on checking out a car that supposedly has a m30 engine and transmission from a 1983 "European" 735i.

            Question is are all European 735i's come with the M90 (shorter stroke & higher compression m30 variant)? What is the best way to identify this motor? I've read that they are suppose to have a 'L' stamped somewhere on the block.
            No, not all european 735is come with the M90 L-block engine, usually it was pre-83 built cars. Yes there was infact an "L" stamped on these motors. Here are a few basic tips/guidelines to determine if you have the euro high compression motor or the earlier M90 "L" block engine.


            - Check the ECU. Late M90s used a very early version of Motronic 1.0 basic, the last the digits of the DME should read 002. The later euro high compression engines used either a "011" or "061" DME.

            - Check the block. The L-Block stamping should be right between or below the #2-4 intake ports (can't remember exactly where) and will be in a white lettering, not cast into the block.

            - Check the pistons. L-block pistons are flat topped, while the euro high compression pistons are domed, with what looks like the shape of a grand piano. Easiest way would be to pull a plug and get in there with a bore scope to check it out. If don't have the $$ or can't borrow a bore scope then just put the motor at TDC and feel the #1 piston.

            Here is an excellent guide showing the difference in pistons - http://www.m535i.org/officers/ra/article.html#motor

            And also remember that the M90 has 9.3:1 compression ratio, is 3453cc and has a completely different bottom end from the Euro M30B34 which is 10:1 compression ratio, but only 3430cc of displacement.

            Hope this helps and let us know how you proceede.

            -Ben
            Originally posted by BillBrasky
            E36's are the Stephen Baldwin of the 3 series family. They barely hold everything together and they only sold a lot because of the popularity of their older sibling.
            1991 318i Alpine II - S50/5-lug swapped - track car
            1989 325i Cirrusblau - Daily
            1970 2500 - Malaga over Grey Cloth
            2012 F350 6.7PSD

            Comment


              #7
              Thanks. I will check and see if it still stamped and the ECU. With the higher compression looks like I'd have to swap pistons if I want to go forced induction.

              I guess that the log manifold wasnt necessarily on all M90's ?

              Comment


                #8
                I guess that the log manifold wasnt necessarily on all M90's ?
                Correct.
                Originally posted by BillBrasky
                E36's are the Stephen Baldwin of the 3 series family. They barely hold everything together and they only sold a lot because of the popularity of their older sibling.
                1991 318i Alpine II - S50/5-lug swapped - track car
                1989 325i Cirrusblau - Daily
                1970 2500 - Malaga over Grey Cloth
                2012 F350 6.7PSD

                Comment


                  #9
                  some euro blocks also have an F on them...

                  I parted a motor out of a euro 6 that had an "F" and the pistons were piano top

                  Comment


                    #10
                    I put an M90 head on my M30B34 block. The head had a cam that was set up for a 90* distributor, instead of the standard distributor that bolts to the front. I compared the cams and the ends toward the front of the motor were different. I vote for M90 engine.
                    1974.5 Jensen Healey : 2003 330i/5

                    Comment


                      #11
                      M90's did come with the "stacked" typical m30 style manifold. I have never seen an m90 with out the vertical dizzy but I havent seen everything. Also '83 I believe is a little late for a m90, I have one that came from a '79 6'er

                      Another way to tell is to look at the driver side of the block, their is a raised coolant passage about half way up the side, if it is short say 3 inchs thats the usual m30, if it is very long, 2/3 of the block long its an m90.
                      Anything can be done

                      Comment

                      Working...
                      X