IMS timing question
 

Hey All,

I asked this question a while ago somewhere here but I had no answer so I thought I ask again before I assemble the engine. My understanding is that the crankshaft has to be lined up with the 4 camshafts, and the IMS position with respect to the crankshaft shouldn`t really matter. However, there`s a punchmark on the IMS sprocket, am I right that I can just ignore that?

If you know the answer or you have assembled a Boxster engine and paid/didn`t pay attention to this alignment I`d appreciate if you could chime in.

Thanks
Greg

Start reading here...http://lnengineering.com/files/IMSR-Pro-Manual-03-23.pdf

Thanks for sharing this, it`s useful. Basically they just lock the crank and camshafts at TDC. Does not say anything about IMS timing with respect to crank position though, but probably it does not matter anyway.

I refrained from replying because I am not a Porsche engine expert. Frankly, I've only ever had the m96 down to its nuthin's once.
But I am somewhat of a very knowledgeable engine builder in my own right. And based on my experience, and even more on what I've read, there's really no reason that it should matter.

So I'm voting with you.

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Yeah, it should not matter. My guess is that it`s for the alignment of the three sprockets on the IMS, as they are three individual pieces and the teeth are not in line. It`s confusing, because it really looks like a timing mark. Here`s a picture just for reference.

http://986forum.com/forums/uploads02...1583091037.jpg

Boy it sure does.
You're likely onto something about it being for assembly onto the shaft. Those sprockets would indeed need to be indexed somehow when they're installed on the shaft.

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If the chains have marked links, it's probably to help you during chain installation. I.e. so you don't have to count the links between the sprockets. Timing belts have marks that line up with marks on the sprockets, so you don't have to count teeth. Maybe these chains do too?

I'm surprised no one on here who actually takes these motors apart has chimed in yet. But, like others who have replied, I believe the IMS sprockets are not timed.

I am really sorry, I did not put attention and assumed that the picture was from one of the Cam Sprockets...
.

Interesting.
What purpose does that serve? What is it "timing" that way?

Apart from the two small chains in the heads, I don`t remember seeing any other chain marked, but I`ll take a second look.

The IMSB external flange is just a mount for the bearing to spin on. If it's a LN bearing just torque the bolts to spec & you are done. I would guess the punch mark is from the machining process.

I know you'll think this rude of me, so I'll be extra sensitive.
I don't think anything in this thread is about the external flange, and so your post is likely to confuse some future reader. (As it confuses me)

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My guess is that the punch has significance if it is lined up to other components. I.E.: you could tell the orientation of other components without seeing them.
Just a guess.
BYprodriver could be right about it being an artifact of manufacturing, though (although seemingly being confused about the component in question).
Having worked in a machine shop, I've put marks in seemingly odd places, either for our use, or to help with assembly in some way.
The way these engines were manufactured in the original facility could have had an important use for that mark. German sophistication often goes much deeper than what is apparent at surface level.

Ultimately, though, I do not think the orientation of the IMS is functionally significant, as it appears to be radially symmetric other than the mark.

I am really sorry, I did not put attention and assumed that the picture was from one of the Cam Sprockets...

No worries!