Intermittent crankcase pressure issues

Small Block Mopar Engine

  1. Deceus

    Deceus Well-Known Member

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    10:04 AM
    You nailed it.

    wpj6XK3.jpg

    The good news is that it seems to be REALLY close to 1/64" (.015625) off still. It's looking like I'm going to get away with re-ringing and rehoning. Have to check the other pistons obviously so wish me luck lol. Got one of the exhaust valves out as well and it seemed good. No marks on the valve and no noticeable play. I plan on building the 360 sitting in the garage in a year or 2 since 400 ft/lbs of torque isn't as scary as I thought it would be in this car so if the 5/64" rings end up a few thousands off it should be fine for it's short life.

    Turns out not double checking tolerances is a bad idea when assembling an engine even when you're with people who have done it a few times. Who would have thunk it?
     
  2. nm9stheham

    nm9stheham Well-Known Member

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    Well, give teringer credit for the big clue here. And BTW, use a feeler gauge thickness that just slips in, but is not tight. If you have .021 now, then with a new ring, it's gonna probably be .004"-.005".... stock is .001-.003". Not sure if the KB's have a bit wider groove or not, or should have a bit more, so you may have some slight to modest groove wear. Really worn grooves have more side clearance than that.

    See if you can figure out how deep the radial groove is up just under the ridge area; that is probably due to the ring twisting as the piston passed TDC and digging into the wall as it started down.

    It's gonna be a lot better regardless, and for a short life, 5/64" rings beats running the thin rings that were in there LOL. And yeah, it just takes one little thing..... At least now you know what proper ring side clearance is now, and will spot this problem by eyeball in the future..
     
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