
Originally Posted by
timsrv
I'm sure I made at least one "long winded" post previously in this thread explaining how to measure/adjust valve geometry. Not sure how it could be off, but something is making a racket. No way to know for sure until you measure for lash (excess play) at each rocker/push-rod. If it is off, then the simplest solution would be to get custom push-rods (pretty sure I gave a link or 2 previously). FYI, this is not a common issue, but I've run into it before. It's usually caused by a machinist who wasn't properly trained and/or wasn't aware these valves are non-adjustable. If it's an aftermarket head, it's also possible there's dimensional errors in the height of the rocker arm mount bosses. Maybe the wrong lifters??? (who knows). Whatever the reason, if it's loose valves, then you'll need to have some custom work done. Over my career as a mechanic, I've only ran into this once. It was on a Ford 460 (also hydraulic lifers with non-adjustable rockers). In that case I was able to shim each rocker stud to obtain correct geometry.
That engine had individual rockers/fulcrums though. Since the 4y uses a common rocker shaft, the only way to adjust would be with custom length push rods. With some careful measurements, math, and some custom push-rods it could be dialed in. Of course that's assuming it's a valve lash issue causing all that racket. Tim