Decoding my M30

['69 2800cs]

I'd like to know what motor I have in my car, and so far I'm coming up blank. It's certainly a replacement motor.

The block has the 3.5 on the side and the head is dated 1983. Current induction is two 32/36 webers.

The motor number is 40813799, which doesn't seem to tell me much, and I don't see any other numbers stamped in the same place. I tried putting the full number, then the final 7 digits into realoem but nothing came up.

The head has the numbers 277 358, which I've read is a casting number and doesn't tell much either.

Any ideas? I'd like to know what I have so I can plan out next steps.

 

[sfdon]

Look on the pass. side of the block for the block date 1st and then run a compression test.
Post your results here.

 

['69 2800cs]

Thanks Don....block date is 1 K 85.

I may be able to get to a compression test this weekend.

 

[x_atlas0]

If it is a M90 block, it should have a different driver side coolant passage than later blocks and have a "L" painted on the block. Hard to read on most cars, though.

http://forum.roadfly.com/threads/11654982-How-can-i-tell-if-I-have-a-SOHC-M535i-Engine

 

['69 2800cs]

An M90...I should be so lucky!

I found the rebuild receipt from 1998...piston part number is 11-25-1-286-438, which indicates an overbore 8 to 1 piston.

I'll still do the compression check when I get around to a valve adjustment.