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Thank you for the input Greg.

wkohler wrote:M90s are a different kettle of fish though. Due to the large bore and shorter stroke, they tend to oval the bores over time. It's worth having them checked.

The piston rings or the cylinder bores? Or both?

Just use M30 ones, a M90 is really just a specific M30. If work was done that recently, it would have good ones if they were replaced, but since you don't know...
Copy that.

Careful, I see mission creep. A shop can't do much more with an assembled short block than you can. Unless you're planning ...

Thanks for the help guys. The head service was done in 2001 or 2002 I believe, but does not specifically mention the seals. I will replace these regardless since I have the time and access. Can I pull the part # from realoem for the M90 specifically or should I be looking for later M30 ones?

As for ...

Thanks for more great info. I had believed the head was never machined, but I remembered a receipt in the folder of records I got from the previous owner (who in turn received it from the original owner) for some headwork done. Here's what the receipt says:

-Diag misfire cyl 2/3 no compression ...

Do you have to deal with smogging the car? It would be interesting to find out if an M90 with Motronic 1.3 will pass a smog test. In general M90s have a reputation of being dirtier than even a Euro M30b34.

If it runs relatively clean, I would love to run Motronic 1.3 with an M90. Those engines are ...

I'd run the B35 cam and I'd also run the B35 intake manifold, too. You'll have to port-match the head, but I think it will be more at home in the E30 than the L-jet manifold.

The very last M90s in the '81 production 635s were Motronic and ran the 002 ECU. They used the 3.2/3.5 intake like the ...

Thank you Mike, that's some helpful and useful information. Do you happen to have a part number or place to look for the adapter you mentioned?

In the event it's not available, I can use a 1/84+ cam that will natively accept the bolt on rotor adapter, I just won't be able to to be certain it will ...

Thanks for the reply Mike. Here is what a well established member on bigcoupe had to offer regarding the cam: "the M30B35 cam is a slightly longer duration/higher lift cam than the one fitted to a euro M90 motor...The cam will lose you a little torque low down but you will get a bit more higher up ...

Greetings! A couple of years ago I bought a grey market euro 1980 635csi locally because I wanted the transmission and engine. After quite some time I finally started digging into it, that I might eventually stick it in here: http://i879.photobucket.com/albums/ab353/4drPwr/HD%20Garage%20Shoot ...