Quote:
Originally Posted by Scrrem
So what do you think the issue was with the ring seal on the first build? I just recently did a 380 build and only have about 800 miles on the motor but am getting a significant amount of blow-by as well. I was thinking my rings just haven't seated in yet but maybe it's something else. Starting to wonder now. Would be intersted to hear your thoughts.
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Well, I'm no expert, but I think it's a handful of things. The bore finish is obviously important. I don't know what hone finish was put on my first build, I will specify exactly what it is on the second one. A cylinder deck plate is a must, especially with open deck (mine is not open deck, and had a plate hone). The quality of the ring pack can't be overlooked either--I'm upgrading that too.
I also think piston stability in the bore hurts us as well. Especially with longer stroke/shorter rods. In the end, I have chosen a slightly heavier piston this time, with longer skirts. Still the box-bridge inboard pin boss design. My belief is that the piston starts rocking around in the bore, the ring seal gets disturbed, and the rings start to flutter at high rpm.
It was a well-built engine, and still had enough blow-by to push the dipstick up an inch under WOT. I never measured blow-by directly with a meter, but I wish I would have. It ran well and made a lot of power, so it couldn't have been too much of a problem.
Todd
PS- your rings should be seated by now. Did you break it in initially with a load? either on a dyno or hard street runs?