304 rocker arm/lifter issues

soundman wrote: Do the lifters "pump up" when the rockers are taken off? And if so, what is the proper way to get these back into adjustment without hanging the valves open?

soundman wrote: Hello all, Having fits with my 304 AMC/Jeep valvetrain. All started with a valvetrain tick, traced it down to the drivers side bank, pulled the valve cover and bridges and saw a couple of bridges galled. Bought new rocker arms and bridges, installed them and torqued them down to 20ft lbs. Started the Jeep, and it ran rough, backfiring, and popping. Backed the bridge cap screws off a couple of threads each and it smoothed right out. Took all the new bridges off to compare to the old ones...identical. Put the old valvetrain back on, and its doing the same thing. Do the lifters "pump up" when the rockers are taken off? And if so, what is the proper way to get these back into adjustment without hanging the valves open? Thanks!   Terry

At some point it's had a reman engine put in, and it wasn't driven much at all, so not sure of the mileage but it can't be many. Ran great, doesn't smoke. Well, it all started with a valve train tick only after the engine warmed up to operating temperature. I traced it back to the drivers side bank rear area of the valve cover. Pulled the valve cover and all the bridges and the rear two bridges (aluminum) were a bit galled, so I went down to the local parts store and bought a set of Sealed Power rockers and bridges. Those had the separate steel pivots and steel strap bridge, didn't think much about it , other than it was a design change. Installed those and that's when the  issue started. Fired it up and would hardly run, bcaked off the cap screws a couple of turns on all that side and it smoothed out. So I thought there was was an issue with the design change. The rockers looked identical, so I scrounged some brand new factory aluminum bridges and bought the full set...last ones he had. After measuring the distance from where the cap screw goes to the area where it sits on the head boss, they all matched the factory ones I pulled off within a couple of thousandths. Put the new alum ones on with the new rockers and same thing....ran rough but backed all off a couple of threads and smoothed out.  Got frustrated and installed all the old rockers and bridges and dang if it was doing the same thing with all the old components.....leading to the question of the lifters pumping up with the valvetrain off. I really have no clue where to go with this now. Appreciate everyones input! 

Class Guy wrote: Here's a possibility.  Rebuilt engine = block decked, heads surfaced = shorter distance from the camshaft to the rocker arms = too much preload on the lifters.  If you put too much preload on the lifters, the engine will run rough at low RPM.  A simple solution might be to put shims underneath the rocker stands (bridges).

amx39068 wrote: Class Guy wrote: Here's a possibility.  Rebuilt engine = block decked, heads surfaced = shorter distance from the camshaft to the rocker arms = too much preload on the lifters.  If you put too much preload on the lifters, the engine will run rough at low RPM.  A simple solution might be to put shims underneath the rocker stands (bridges).   That should not account for the before and after change with nothing else different other than new rocker assemblies.