Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
323 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said cylinder block, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 2
Dependent Claim
323 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said cylinder block, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 3
Dependent Claim
22 words
The combination defined in claim 1 in which said first and said second bores in said cylinder block are of equal diameter.
Claim 4
Dependent Claim
43 words
The combination defined in claim 1 in which said valve lifter includes a foot portion which rides on the surface of said cam continuously during the rotation of said cam, said valve lifter stem being carried by and extending from said foot portion.
Claim 5
Dependent Claim
49 words
The combination defined in claim 1 in which said valve lifter engages said valve stem to impart rotation to said valve substantially only during the portion of the cycle of rotation of said cam in which said head portion of said valve is not seated on said valve seat.
Claim 6
Dependent Claim
42 words
The combination defined in claim 1 in which said cylinder block is provided with a hollow spring chamber, said first and said second bores in said cylinder block communicating with said spring chamber, said spring means being positioned in said spring chamber.
Claim 7
Dependent Claim
323 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said engine body, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 8
Dependent Claim
323 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said engine body, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 9
Dependent Claim
22 words
The combination defined in claim 6 in which said first and said second bores in said engine body are of equal diameter.
Claim 10
Dependent Claim
43 words
The combination defined in claim 6 in which said valve lifter includes a foot portion which rides on the surface of said cam continuously during the rotation of said cam, said valve lifter stem being carried by and extending from said foot portion.
Claim 11
Dependent Claim
49 words
The combination defined in claim 6 in which said valve lifter engages said valve stem to impart rotation to said valve substantially only during the portion of the cycle of rotation of said cam in which said head portion of said valve is not seated on said valve seat.
Claim 12
Dependent Claim
42 words
The combination defined in claim 6 in which said engine body is provided with a hollow spring chamber, said first and said second bores in said engine body communicating with said spring chamber, said spring means being positioned in said spring chamber.
Claim 13
Dependent Claim
305 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, said first bore being adapted to guide said valve stem, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said cylinder block, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to said valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 14
Dependent Claim
305 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, said first bore being adapted to guide said valve stem, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said cylinder block, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to said valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 15
Dependent Claim
43 words
The combination defined in claim 11 in which said valve lifter includes a foot portion which rides on the surface of said cam continuously during the rotation of said cam, said valve lifter stem being carried by and extending from said foot portion.
Claim 16
Dependent Claim
49 words
The combination defined in claim 11 in which said valve lifter engages said valve stem to impart rotation to said valve substantially only during the portion of the cycle of rotation of said cam in which said head portion of said valve is not seated on said valve seat.
Claim 17
Dependent Claim
42 words
The combination defined in claim 11 in which said cylinder block is provided with a hollow spring chamber, said first and said second bores in said cylinder block communicating with said spring chamber, said spring means being positioned in said spring chamber.
Claim 18
Dependent Claim
304 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adpated to seat on said valve seat and a stem portion, a first bore in said engine body, said first bore being adapted to guide said valve stem, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said engine body, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 19
Dependent Claim
304 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adpated to seat on said valve seat and a stem portion, a first bore in said engine body, said first bore being adapted to guide said valve stem, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted lying on said common axis of said first and said second bores in said engine body, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby rotation of said cam imparts rotation to valve lifter, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 20
Dependent Claim
43 words
The combination defined in claim 15 in which said valve lifter includes a foot portion which rides on the surface of said cam continuously during the rotation of said cam, said valve lifter stem being carried by and extending from said foot portion.
Claim 21
Dependent Claim
49 words
The combination defined in claim 15 in which said valve lifter engages said valve stem to impart rotation to said valve substantially only during the portion of the cycle of rotation of said cam in which said head portion of said valve is not seated on said valve seat.
Claim 22
Dependent Claim
42 words
The combination defined in claim 15 in which said engine body is provided with a hollow spring chamber, said first and said second bores in said engine body communicating with said spring chamber, said spring means being positioned in said spring chamber.
Claim 23
Dependent Claim
337 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 24
Dependent Claim
337 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 25
Dependent Claim
337 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 26
Dependent Claim
337 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, a first guide bushing in said first bore, a valve stem guide bore in said first bushing concentric with the inner diameter of said first bushing, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a second guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said second guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said second guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 27
Dependent Claim
318 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, said first bore being adapted to guide said valve stem, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 28
Dependent Claim
318 words
In combination, a cylinder block for a reciprocating internal combustion engine, a fluid passage in said cylinder block, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said cylinder block, said first bore being adapted to guide said valve stem, a second bore in said cylinder block lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 29
Dependent Claim
318 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, said first bore being adapted to guide said valve stem, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.
Claim 30
Dependent Claim
318 words
In combination, an engine body for a reciprocating internal combustion engine, a fluid passage in said engine body, said fluid passage terminating in an opening bounded by a valve seat, a reciprocably movable valve movable relative to said valve seat from a closed position in which said opening of said fluid passage is closed to an open position in which said opening of said fluid passage is open, spring means normally biasing said valve to a closed position, said valve comprising a head portion adapted to seat on said valve seat and a stem portion, a first bore in said engine body, said first bore being adapted to guide said valve stem, a second bore in said engine body lying on a common axis with and in axial alignment with said first bore, a guide bushing in said second bore, a valve lifter including a valve lifter stem adapted to engage and move said valve to open position, a rotatable cam mounted on a cam shaft and adapted to engage said valve lifter during the cycle of rotation of said cam whereby to cause said valve lifter to move said valve to open position, the central plane of said cam as measured in the lengthwise dimension of the cam shaft on which said cam is mounted being offset relative to the axis of said valve lifter stem whereby rotation of said cam imparts rotation to said valve lifter, a bore in said guide bushing for receiving and guiding the movement of said valve lifter stem, said bore in said guide bushing being eccentric relative to said common axis, whereby the axis of said valve lifter stem is eccentric relative to the axis of said valve stem, said valve lifter being engageable with said stem portion of said valve during the cycle of rotation of said cam whereby to impart rotation to said valve relative to said valve seat.