WTB: 2.0ltr M20 6cyl Head (M20B20)

[riverdale21]

Want to buy a used M20B20 cylinder head from the M20 2.0 liter 6 E30 320i.

[SchnellerVert]

What model? Distributer head or Motronic? This is an important factor.

[riverdale21]

Motronic

[SchnellerVert]

You can't use a Eta head?

[riverdale21]

I read the M20B20 head had the largest stock port size out of the M20's

[Ruffian]

This is the same head as the 323i. While much bigger than the eta head, the ports are smaller than the b25 head. The beauty of the b20/b23 head is that you don't have the ridiculously low compression ratio when putting it on the eta block.

That said, I do have one(from the b20), and would be interested in hearing your offer. As far as with the distributor or not, I believe that's just a simple matter of changing the cam/timing belt gear.(please feel free to correct me if not)

[rs4pro3]

only the 731 head has the big ports(euro 323i), the B20 has a standard eta head

[euro3]

This is the same head as the 323i. While much bigger than the eta head, the ports are smaller than the b25 head. The beauty of the b20/b23 head is that you don't have the ridiculously low compression ratio when putting it on the eta block.

That said, I do have one(from the b20), and would be interested in hearing your offer. As far as with the distributor or not, I believe that's just a simple matter of changing the cam/timing belt gear.(please feel free to correct me if not)

The cam gear has a dowel for the motronic unit (for timing). The earlier model cam shaft is missing the dowel so it would be very difficult to get the timing right.

[Ruffian]

only the 731 head has the big ports(euro 323i), the B20 has a standard eta head

Just not true. Actually, let me clarify, YES the 731 head has the big ports, and NO, the b20 doesn't have just a standard eta head. The b23 and b20 of the m20 variety have the same head. backed up by realoem, and backed up by my going outside and looking at the head of my euro 320i

[Ruffian]

The cam gear has a dowel for the motronic unit (for timing). The earlier model cam shaft is missing the dowel so it would be very difficult to get the timing right.

I also believe this is incorrect, as both cams should have the dowel. The only difference is that the earlier units had the adapter that allowed for adjusting/turning the cam with a 1/2" socket mounted to the outside of the camshaft timing belt gear. The later units had the three bolt adapter on the outside of the gear for bolting the rotor to the cam.

I attached the two real oem pictures for example. Both pictures are taken from an early('84) 320i euro. They show the differences between the distributor model and the camshaft mounted distributor(motronic) model.

Basically, the dowel is necessary to ensure that the gear doesn't spin. In all cases, the dowel holds the gear in the correct position for lining up the timing.

[SchnellerVert]

What 320i are you taking about? There are two variants of it.

[Ruffian]

I'm not sure what kind of variant you're talking about. My references are to the e30 6 cylinder 320i with the designation m20b20. This is a eurospec only car that wasn't available in the u.s. Some e21 models had the same engine and are referred to as the 320i/6. Other e21 models had the m10 in a 2.0 liter configuration and still some e21's had an m20 6 cylinder that wasn't designated as a 320i, but rather a 320. That non i motor was never issued in an e30.

So the OP asked for a head from the e30 m20 2.0 liter 320i, so I figured that's what we're talking about. Regardless of motronic or distributor configurations, the head is identical except for the cam gear configuration noted above.

I'm not a know-it-all, my wife will attest to that, so if you know something different, please explain.

[SchnellerVert]

Well there was the early metal bumper 320i which had 92kw or 125hp and was L jetronic and then the later model pastic bumper cars had 95kw Motronic that's 129 hp.


The valves are slightly differant sized between the two variants.

[Ruffian]

Well there was the early metal bumper 320i which had 92kw or 125hp and was L jetronic and then the later model pastic bumper cars had 95kw Motronic that's 129 hp.


The valves are slightly differant sized between the two variants.

The 4hp was a change between the engine management. There is no difference between the valves. If you have a link or something, I'd like to see it.

[SchnellerVert]

I will look for it, I seem to remember there is and Eli can chime in on it. The 731 head is what you want for an eta conversion for ease factor.