M42 cam vs M50 cam

[colin86325]

Hypothetical question here, as I'm just speculating.

Has anyone tried to adapt an M50 cam to work in an M42?  Since the two engines are relatively similar, I'm wondering whether the M50/S50 (US) cam can be shortened to fit in the M42.  Sorry if this is a stupid question, but if I had an M50/S50 cam in front of me I would just do the measurements myself.

I'm just looking for a mild cam upgrade and the idea crossed my mind.

[Boyracer]

I can think few reasons why it might not work:

1. If you just chop off 2 cylinders worth of cam lenght away from 6 cylinder cam and stick it to M42 I'm am pretty sure the cam lobes are not in synch with pistons and rest of the bottom end. So valves are open/closed in the wrong time. You could chop the cam to number of pieces and then reweld the pieces to correct angles but I have large doubts if such camshaft would stay intact for any lenght of time in use.

2. Some M50 cams can be actually milder then M42 cams with less duration and lift. Because of VANOS they can use less duration but they can change the timing to suit the rev band the engine is on. I think M50 (not sure if it is called M50 but it basically is M50B30...) used in US M3 has most aggressive duration and lift but not sure if even that is any bettern than stock M42.

You cannot use euro S50B30/32 cams because they are designed for solid valve lifters/followers so the cam lobe profile is unsuitable.

In my opinion you are better of by regrinding stock cams.

EDIT: I think option that might work easier is M60/M62 V8 engine family since they have same amount of cylinders on one block. But I have no idea if the cam lobes align with bottom end timing on this option either.

[Ricer Ennemi]

What about putting a S85 V10 crank.

[Warsteiner]

I agree with Boyracer on all points.  You CAN however take the cam trays and cut off two cylinders and make a few other minor modifications and lighten your valve train from 35mm buckets to M3 33mm buckets:)  You can also have your cams welded and grinded to whatever you want at a reasonable price.

~Ralph

[Romrog318is]

why go the route of trying to make a 6 cyl cam that wont ever work and not just get a set of customs cams? and im sure there are companies out there that will make cams for you

oh and the us M3 uses an S50B30 in the 95 model and S52B32 in the late model

[bmwman91]

Simple answer: No, it cannot work for physical reasons that cannot be worked around.

On a an inline-4 motor with a DOHC configuration, cam lobes are offset 90 degrees from one another.  A DOHC inline-6 will have its cam lobes separated by 60 degrees.  It should now be fairly clear why you cannot just chop off one third of an M50 cam & stick it in.

Even IF you could, it would probably cost far more for the custom machine work than just buying a hot Schrick M42 cam set.

[autox320]

Won't work but

Can send your cams to Delta and get welded and ground for M3 spec. Having mine done now, $300/pair. Let ya know how it turns out in July when I get a chance to install them.

[deekay]

What about putting a S85 V10 crank.

what an idiotic way to resurrect a 2-year-old thread.

[Romrog318is]

^^^ hahahah

[colin86325]

Haha, old thread.  I think i was drunk when i posted that nonsense

I ended up getting an intake cam from Web cams.