DieselJeepLuvr wrote:
WolverineFW wrote:
But do you understand why there are 3 different head gasket thickness?
Yes.
One thing to consider is, in WW 's reply it refers to the piston protrusion from the liner NOT the deck. And it says to use the average clearance NOT the least which I disagree with. I've observed depressions in the head where the sleeve has hit hard against it. This would give a lower compressive strength to the head gasket and possibly increase the chance of head gasket leaks, warping and/or cracking the head. That's why we always say to use the 2 hole gasket. Better safe than sorry.
If you study the FSM, it covers
piston liner protrusion from the top of the deck and choosing the correct liner shims accordingly.
But I think what they are most concerned with is how close the top of the piston (
piston protrusion above top of liner) will be to the bottom of the head?
From the FSM wrote:
NOTE: When installing liners for protrusion measurement, remove all O-rings and discard original shim.
2) Measure the liner recess relative to block deck with dial indicator.
NOTE: The cylinder liner reading will actually be a negative number.
5) Then select the correct shim thickness to give proper protrusion (0.00 - 0.05 mm, liner protrusion above top of engine deck)
Without knowing the ramp curves and lifts for the cams, we don't know exactly how close the tolerance (clearance/gap) is between when the intake & exhaust valves at full open when the piston is close to TDC. We know this is an "interference engine" and valve timing is crucial and can and will allow valve contact to the top of the piston if the cam timing gets too far out of the required specifications. So head gasket thickness might or could actually play into this clearance when the piston is approaching or leaving TDC?
Certainly something to consider...
Comments or thoughts more than welcome, as this is always a good discussion subject and helps to understand some of the nuance's of this very unique engine!
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