M103 Head Compatibility (Late vs Old)
 

Hello,

I am wondering how compatible a late model cylinder head is with an old M103 block. I currently have an 86 M103 3.0 motor sitting in my garage that I plan to throw into a 201 as an upgrade. But smog requires me to have a functional smog pump to pass visual inspection. The 86 M103 does not have a port on the cylinder head for smog pump.

I'm wondering how compatible a late model head with smog pump is against the old block? Is it pretty much bolt on and it works? Or are there some significant differences I need to pay attention to?

Or is it not worth it in the end and I should find a proper late model M103 3.0 with smog pump?

Thanks in advanced.

Chamber design changed for the late heads, in addition to the AIR injection crap plus EGR. My guess would be late head on early bottom end would reduce static compression among other issues.

Truth be told, 103s are so common here in Texas at least, I would just find the proper model you need to save the hassle.

I assume you are putting a 3.0L ,103 into a W201 which already has a M103 2.6 in it.

Trying to put a M103 into a 4 cylinder W201 is a massive job. It's easier to source a m103 engined car than upgrade.

It wont work. Someone over at benzworld did it last month and the valves were touching the pistons. The chamber is a different shape to start.

You MUST find the identical head.

Further - The M103 2.6 litre engine head is different to the M103 3.0 litre head.