Hey guys, I am using stock rockers on gt40p heads. I am using the factory mustang pushrods. I made sure the valves were closed on that cylinder and tightened them down to 18ft lbs. Now they are all done, but on most of them when the vale is mostly closed the rocker and push rod still wiggles around alot, is that normal or do I need new pushrods or someting?
when we used to build high rev CBR engine's we had a saying "A slappy valve is a happy valve" better to have more slack then too tight and burn a valve, not sure how much that applies to Ford engine but i would imagine its not too different
Are you asking if you should be able to turn the rocker on the pedestal? If that is what you are asking the rocker bases should be sitting in a u shaped piece of metal that is designed to keep them from twisting on the pedestals. They should have been been some of them under the stock original rockers. It almost sounds like you don't have the metal rocker base holders if the rockers are twisting. edit: you can see a pic of the holder on page 55 picture #9 of the link that Duncan posted
No I do have the base holders, they are not twisting, but I can wiggle them around, someone on corral said its normal because there is no pressure on them when the valve is closed which makes sense.
If you had this same rocker, pushrod, head gasket setup as before and didnt have any problems before, just bolt em down and go. nothing should have changed. If you changed something like heads, gaskets or rockers or anything that would affect the valvetrain geometry. you need to measure for new pushrods. To do this. Put a cylinder on the base circle of the lobe (rotate until both valves shut, right after intake valve shuts on compression stroke). Then setyour rocker down and verify the rocker tip to valve stem relationship is in check. If running roller rockers, the roller tip needs to be SLIGHTLY on the intake side of the center of the stem. so when the rocker moves, the roller will move out some and center your roller tip while its moving. If its not correct. if you have a pedestal rocker. you need to either shim the rocker up (if the wear pattern is too much on the intake side) or mill the pedestals (if the wear pattern is too much on the exh side.) Then get and adjustable pushrod and open it out until zero lash (no slach but not depressing lifter plunger), measure the pushrod and add the desired preload (anywhere from .010-.050 usually). then get your new pushrods that length and bolt em down and you should be pretty good. If you have stud rockers. you dont need worry about that. you simple need to get the correct pushrod length, with a stud rocker setup, the adjustment is in the pushrod. Best way to do it is to grab a rocker and nut and the adjustable pushrod and adjust the rod and spin the nut down until the rocker tip is correctly located. (make sure your at zero lash and on the base circle of the cam) then take out the pushrod and measure it, then add your desired preload to that measurement. Then when you go to set the rockers up. You will need to find zero lash and then rotate the nut down past zero lash to set the preload then set the locknut. on a 3/8-24 stud, 1/4 turn is roughly .010... so if you set it up for .030 preload, 3/4 turn is what you need. Also with the stud rockers. every rocker needs to be installed on the base circle of the cam lobe.
Well I am using new pushrods but same length, and I am using different rockers, stock, vs. scorpion last time.
