Abstract:
An adjustable pushrod guide plate assembly including a first plate and a second plate. Each plate defines an adjustment slot. The plates are in an at least partially overlapping configuration, the slots are optionally aligned, and a shaft is disposed at least partially through the slots to join the plates. The shaft can be a fastener adapted to be manipulated to secure the plates in a variety of fixed configurations.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to guide plates for use with internal combustion engines which include overhead valves, and a related method of assembly. 
   Many internal combustion engines include overhead valves that regulate the intake of fuel and air into one or more combustion chambers, as well as exhaust out of the chambers. Pushrod guide plates are usually employed with overhead valves to align a rocker arm with a tip of a valve, both in longitude and latitude, that is, the plate squares and positions properly (from left to right) the rocker arm relative to the tip of the valve. 
   Guide plates typically are positioned between the rocker arms and the bosses atop the cylinder head of the engine. The plates generally include two holes for mounting the guide plate to the cylinder head with bolts, and two slots, one of which is dedicated to guiding an intake pushrod, the other of which is dedicated to guiding an exhaust pushrod. 
   Most guide plates are mass-produced using conventional manufacturing techniques, such as stamping. Mass-produced plates are usually constructed from a single piece of rigid material. 
   A problem with conventional guide plates is that although they are usually well-manufactured, slight deformations that occur during stamping can make the plates incompatible with and unacceptable for high performance factory or aftermarket cylinder heads. Additionally, when installing conventional guide plates on highly specialized or high performance engines, which include intake cylinder ports and/or exhaust ports that have been relocated, the pushrods usually fail to align with those conventional plates. 
   A proposed solution to this problem is disclosed in U.S. Pat. No. 5,044,329 to Jamora, which shoes a two-part guide plate, where one plate includes a tab and the other plate includes a complimentary slot. The two plates can be moved, tab in slot, until a desired configuration is achieved, after which the plates can be welded together. Although this construction offers a partial solution, it also has its shortcomings. For example, if the pieces are welded, there is no way to correct any misalignment that may have occurred while the pieces were being welded—short of cutting and re-welding the pieces. Further, if the guide plates are removed and the pushrod position is altered, the welded guide plate parts must be cut and welded again to accommodate the new position. Finally, in some cases, the welding of the plates causes slight warping of the plates, which can alter alignment of components. 
   SUMMARY OF THE INVENTION 
   The aforementioned problems are overcome by a two-piece pushrod guide plate assembly which includes a first piece and a second piece, each piece including a pushrod guide slot, a plate mounting aperture, and corresponding adjustment apertures. A shafted element and/or fastener is positioned through the apertures to join the first piece and the second piece. Optionally, the pieces can be in a partially overlapping configuration, with the fastener tightened to secure the pieces in a fixed orientation relative to one another. 
   A method for assembling the guide plate assembly is also provided. In one embodiment, the method includes providing the specialized guide plate assembly pieces; positioning the first piece adjacent the second piece so that the adjustment apertures of each piece are at least partially aligned, and positioning a fastener at least partially through the apertures to join the pieces. Optionally, the method can include placing the pieces in a partially overlapping configuration, and fastening the fastener. 
   The guide plate assembly and related method provide a simple and inexpensive, fully adjustable guide plate assembly that is easy to install and use with any high performance factory or after market valve trains. In addition, the guide plate assembly overcomes the conventional problems associated with one-size-fits-all, mass-produced guide plates. For example, it provides the adjustability necessary to accommodate overhead valve trains where pushrod placement has been altered and/or near perfect alignment of components is required. 
   These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the invention and the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a guide plate assembly of one embodiment; 
       FIG. 2  is an exploded perspective view thereof; 
       FIG. 3  is a front view thereof, the assembly being mounted to a cylinder head; 
       FIG. 4  is a side view thereof; and 
       FIG. 5  is a first alternative embodiment of the guide plate assembly. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An embodiment of the guide plate assembly is shown in  FIGS. 1–4  and generally designated  10 . The guide plate assembly includes two pieces  20  and  30 . Each piece  20 ,  30  of the assembly includes a mounting aperture  22 ,  32  along with a pushrod guide slot  24 ,  34 , respectively. The mounting apertures are designed to accommodate a mounting fastener  102  ( FIG. 3 ) that secures the plate to a cylinder head  100  of the engine. The pushrod guide slots  24  are adapted to properly align the pushrods  104 . In general, one guide plate assembly  10  is dedicated to a single cylinder and associated portion of the valve train of an internal combustion engine. The components of the guide plate assembly, including the fasteners and pieces, can be constructed from various materials including steel, titanium, alloys and other metals and/or synthetic materials. 
   Each guide plate piece further includes respective arms  26  and  36  which project toward one another. The pieces further define mounting apertures  43  and  41 . As used herein, aperture can mean a hole, slot, recess or combination thereof. As shown, the apertures  43  and  41  are generally in the shape of slightly elongated slots. These apertures, however, can be formed in any desired shape, for example, as elongated slots, moon-shaped slot, or for example, as holes that are slightly oversized relative to the fastener  40 . 
   The fastener  40  is positioned at least partially through each of the apertures  43  and  41  to join the pieces  20  and  30 . The fastener may include complimentary portions, for example, as shown, a threaded bolt  42  and a nut  44 , which can be tightened to secure the pieces  20  and  30  in a fixed orientation relative to one another. Although the fastener shown includes a nut and bolt combination, the fastener  40  can be other types of fasteners, such as screws, rivets, grommets and the like as desired. Other shafted elements, which means any element with a shaft of any shape or cross section and can include fasteners, can be used to join the pieces as desired. 
   In the embodiment shown in  FIGS. 3 and 4 , the guide plate slots  24 ,  34  and mounting apertures  22 ,  32  of the separate pieces  20  and  30  can be configured so that they rest in different planes. As shown, the first pushrod slot  24  is in a different plane from the second pushrod slot  34 . The relative planes in which the slots and apertures are located can vary as desired. For example,  FIG. 5  illustrates an alternative embodiment of the guide plate assembly  110  including first and second pieces  120 ,  130  which are in the form of flat, partially overlapping plates. The pieces  120  and  130 , however, are almost in the same plane, giving the assembly a flatter profile than the embodiment described above. The pieces  120  and  130  of this embodiment, however, are secured together using the same components as the embodiment described above, that is, a fastener  140  is positioned at least partially through aligned adjustment apertures  144  of the pieces. 
   Returning to the embodiment shown in  FIGS. 1–4 , the first piece  20  and second piece  30  are in an at least partially overlapped configuration, where part of one piece  20  overlaps the other piece  30 . In this configuration, the apertures  41  and  43  are at least partially aligned in the region through which the fastener  40  is positioned. When tightened, the fastener can compress the overlapped pieces together in a secured orientation. 
   Assembly of the guide plate  10  will now be described in connection with  FIGS. 1–3 . Generally, the guide plate pieces  20  and  30  are positioned near one another. With the adjustment apertures  41  and  43 , at least partially aligned, the fastener  40  is positioned at least partially through both of the apertures  41  and  43 . The fastener  40  can be tightened at that point to compress the pieces  20  and  30  against one another. The entire guide plate  10  is then positioned on the head  100 , the mounting studs  102  are inserted through the respective mounting holes  22  and  32  to secure the guide plate to the head. The pushrods  104  are inserted through the pushrod guide slots  24  and  34 . The remainder of the engine valve train is set into place and the positioning of the pushrods is determined. After appropriate pushrod placement has been determined, the fastener  40  is tightened to secure the pieces  20  and  30  in a fixed position relative to one another and ensure proper pushrod alignment. 
   The above descriptions are those of the preferred embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.