Thread: Too much crankcase pressure, novice engine builder

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Back to the original problem.. excessive pressure causing seal failure(s).
Back in this thread you mentioned that it only happens at 6K rpm or above. So my new theory is your probably running a high volume oil pump and at that high rpm your pumping oil up into the heads, flooding them and this causes a "trap" the pressure has no place to go. So it seeks a weakness. A loose fitted seal, or the Chinese wall ... It's called a windage tray because it "breaks" the wind shear or turbulence around the spinning crankshaft, this allows the oil to get out of the "wind" and settle to the bottom, where you can pump it back for another cycle.

My other thought is your selection for the ring end gap is excessive. If you aren't running boost, don't worry about building a motor for the added boost pressures. You said it yourself, rings are cheap. Build the motor for the duty it will perform, not for what you "want someday"...

And another thought, drop some of the bearing caps.. the ring materials went somewhere! Find it before you close the motor up.

My last thought.. a "guy" with a dyno, who can't handle a carb.?.? He is NO tuner! But that's my opinion I guess. You know a carb has like 2 moving parts right?? 36Sedan has a couple of great write-ups posted around here.. The link above from him is a keeper! Hint /Hint... PRINT IT! LOL.

Originally Posted by 34_40

My other thought is your selection for the ring end gap is excessive.
And another thought, drop some of the bearing caps.. the ring materials went somewhere! Find it before you close the motor up.

Fair points. I am reducing the gap this time around. Every piece will be removed from the block and cleaned well before placed back. As for the oil pump, it's an brand new OEM style pump. I still think excessive blow by was the main culprit here.

Originally Posted by 34_40

My last thought.. a "guy" with a dyno, who can't handle a carb.?.? He is NO tuner! But that's my opinion I guess. You know a carb has like 2 moving parts right?? 36Sedan has a couple of great write-ups posted around here.. The link above from him is a keeper! Hint /Hint... PRINT IT! LOL.

As for my tuner, I'm sure he's fully capable of messing with carbs, he just gets enough business with fuel injection he doesn't have to mess with carbs. It's not worth his time and I understand