Quote:
Originally Posted by ischmitz
Wow, I am following this thread very closely because I might at some point also go down this path. While I have timed 911 and 964 engines from scratch I never worked on the 996 yet.
Let me see if I have this straight:
The Pelican procedure suggests jamming the large IMS sprocket with three set screws through the case threads. I guess this is questionable as you either go too hard (stripping the threads in the case) or too light (not enough friction to stop the sprocket from moving laterally or rotationally given its surface where the set screws touch is slick with oil). The cams are loaded from some valves being pushed open. So the cam train acts on the chain (push or pull depending on degree to TDC1). The hope is that the IMS sprocket doesn't move and that the chains don't skip on any of the sprockets once the chain tensioners are removed. Hmmm...
The LM procedure has you move engine to TDC and lock the flywheel with a pin and then has you lock cam shafts in place with special cam holders. I can see where that eliminates any push or pull on the chains. I can see the downside is you need special tools (cam holders). Do you also need to remove valve covers?
Are these the only differences between the two procedures?
If so I guess the two variance in the Pelican procedure that "decide" about success or failure are:
- the torque on the three set screws; not enough and the shaft gets pulled off center, too much and there goes your case
- the degree from TDC1 you end up with when all three openings in the case show a solid metal surface of the IMS sprocket? lucky, no skip or else.....
Comments from the experts?
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The unfortunate answer to your question is to totally ignore the Pelican procedure and follow the LN directions
to the letter (no short cuts or skipped steps). LN and Jake Raby developed this method and to my knowledge is the only one that will work first time, every time. We have used the LN procedure for years without any problems.