M40 Exhaust Manifold on M42?

[markpopaj]

Hello,

I'm picking up a M42 this weekend to replace my M40b18 in my RHD touring. The engine should drop right onto the existing mounts and bolt right up to the transmission (salvaging the M40 flywheel). My biggest worry is will the M40 exhaust manifold bolt onto the M42? If not, are the LHD and RHD exhaust manifolds extremely different. Some say the steering coupling is in the way, but can anybody confirm?

I already posted to M42Club, but I figured I might have better luck on here.

Thanks

[roguetoaster]

I don't think the bolt patterns are the same between M40 and M42. As to LHD stuff fitting RHD, the part numbers are different, but I can't quickly dig up a visual reference, so I don't know how they differ.

[bmwman91]

I managed to find some photos of a stock RHD M42 manifold in someone's Photobucket through an old M42Club post. It's pretty different than the LHD manifold, enough that I am pretty sure that the LHD one would not clear the steering hardware in a RHD car. At least you can see the bolt pattern, so maybe the M40 manifold would bolt up.

[roguetoaster]

Pretty sure the M40s run a diagonal offset two bolt per extractor setup.

[varg]

^Yep. M40s have a very different flange, it won't work. It would probably be cheaper to have someone make you a custom header that will fit around the steering shaft than to get a RHD header imported from the UK. I used to have a picture of the RHD M42 header which nicely showed the difference between it and a LHD header kicking around somewhere but I can't find it now. May as well get a custom header made and turbo it as well