Jimmy: With the intake block, it is my understanding that over time they can become fatigued from heat and very minute cracks can develop. The 394 that I rebuilt for the tree service was giving me fits as I tried to dial in the jetting. I replaced that intake block and it cured the tuning issues. But then again, we are talking about parts that are near 20 years old, some older. The same type of thing does happen to a rubber intake boot as well. I guess it's really tomato/tomaahhto. Good thing is that the intake blocks are still available.. Thanks for your insight, I appreciate feedback and advice from those with experience with a particular model.
Wolverine: I see that you trim the 395 filter cover, looks easy enough.. Is this to allow fitment on a 394 cylinder cover?? If so that's cool because I won't have to get a new cylinder cover, just the filter cover and filter mount... For some reason I was thinking I would have to get a cylinder cover as well.....