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Old 07-11-2005, 08:29 AM
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vettestr vettestr is offline
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Join Date: Dec 2001
Location: Glendale, AZ.
Cobra Make, Engine: Cobray-C3, The 60's body lines on todays chassis technology
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Hey 69,
The best path to pushrod verification is to watch the travel of your rocker. Regaurdless of the length (it may have been changed or installed to correct the geometry). When you deck block = heads = line bore = or hone cam bores for any reason it alters the BIG picture or relationship and stack up of all these paramiters that are magnified by the rocker ratio in the end.
There are many web sites that can explain much better than my writting abilities. What you need to check or verify is the fact the rocker face is contacting the valve stem face properly. You have a stud in the head that your rocker pivots on = the pushrod is moved up and down by your cam (various lifts etc..) You can also install different ratio rockers that make checking the proper reference to each other a must.
@ valve closed cam just starting to open each valve you check to see valve stem face is contacted by rocker in/on the centerline. As valve goes to full open the rocker face contacts the valve face in a new place or moves off centerline. If your rocker moves too far from centerline of valve it imparts a great side load on valve to valve guide in head (very BAD). This is corrected or fixed by altering the pushrod length. I have a threaded pushrod in toolbox that I can screw in or out to perform tests and then order proper length pushrods. On my old hemi drag engines you use adjustable P. rods to set lash because rocker shafts were not adjustable!
This should be checked on every engine built !! as you never know if somebody machined the hell out of something before it came home with you. Adding a big cam and different rockers ratios also changes this contact point. Your builder knows this and checked during assembly so do not worry about your engine IT WAS checked during build if a good builder and it will put up with some error anyway. Vettestr
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