Reply to "Bent push rods"

Honken, you must adjust the valvetrain geomery when parts are changed/upgraded. First, the rockerarms must touch the valve stems as close to the center of the stem ends as possible and this may require the pushrod guideplates to be cut apart, positioned correctly, then tack-welded back in position. Second, the rockers may need to be adjusted with slightly longer or shorter pushrods to center them on the valvestems. You blacken the end of the valvestems with a Magic Marker, then manually turn the engine over two full revolutions and examine the stem. If the mark is smeared too close to one edge or the other, the pushrod length(s) must be altered. There are checking-pushrods sold to find the proper length, and many shops make up longer/shorter custom pushrods. Adjustable pushrods don't work in high rpm engines- they are far too heavy and won't hold an adjustment anyway. Note that ALL 16 rockers should be checked and some engine combinations will require two different lengths of pushrod. Intake & exhaust valves have different length stems, anyway. Finally, if things check out OK, very stiff valvesprings and hgh revs may need larger diameter than stock pushrods which will be stiffer. Stock pushrods are 0.060"-wall x 5/16" OD while real race engines use 0.090-to-0.120-wall x 3/8 or even 7/16" OD pushrods for high revs w/stiff springs. And of course, the larger diameter pushrods will need larger clearance slots in the pushrod guide plates, and those slots are not straight up and down but are cut at a compound angle just like the valves. They're hardened, too so simple drilling won't work- they must be ground. Grinding the slots while mounted on the engine is a very bad idea- you'll NEVER get the hard grinding dust completely out of the engine without damage to the bearings.