Quote:
Originally Posted by dannobee
I'm not arguing about the "fretting" that one sometimes sees, I was arguing a different point. Does it make a difference on the dyno? Does it increase reliability? Which race engines did Porsche ever shuffle pin?
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I know this thread is about case sealant but it seems to have wandered into shuffle pinning. As the only guy in the world who actually makes a cast engine case and machines it in house, I have a Liam Neeson like "peculiar set of skills" that makes me uniquely qualified to comment on these issues.
1. Anything you put on the main webs, and I mean ANYTHING, affects the roundness and dimensions of the main bore. We line bore our cases with a $4000 line bore made by the Italian company D'Andrea. It is a boring head that is accurate to .0001 inches (1/10th). No, someone like Ollies does not have this. And they don't have the 300K CNC mill to run it either. What am I saying here? It takes accurate equipment to create a Porsche spec 3.6 bore of 65.000-65.019mm. Not a lot of room within that spec.
So starting with both case halves flat to less than 2/10ths, we then bolt the cases together and bore the main bore as well as the layshaft bore. But before we can consider any of this, the case mating surfaces must be PERFECTLY CLEAN. No dust, dirt or grime can be on the case halves, and certainly something like Loctite 574 would be thick enough to throw off the measurements.
If you think that all of it gets pushed out when you tighten the bolts, my question would be - then why use it? Clearly, the experiment with the 123 blocks shows that enough of it remains to influence the measurement.
On a micro level, you are creating an oblong bore whether you care to believe it or not.
2. Shuffle Pinning - Since most of my customers are engine builders I have heard every tale, story, and anecdote about shuffle pinning that exists. I believe or take stock of exactly none of them, and I just do what my customers ask. The overwhelming consensus has been to sleeve every through bolt with a bushing the same as the one found on the #1 bearing end. So 14 sleeves.
This does 2 things - 1) it prevents the case from moving obviously, and 2) it does what the Loctite is supposed to do: keep the oil in the through bolt bores inside the mains by acting as a bridge.
Therefore, we DO NOT recommend coating the main webs with ANYTHING because you already have shuffle pins on each hole and there will be no leaks due to the same shuffle bushings. Oh, and your bore is round.
Pic attached of ours.
Your mileage may vary.
