I had a friend build me a 598 a few year ago . It was totally assume in a 28 ft sunsation .

I understand your frustration but I can definitely see a set of pistons sitting around on a shelf for 4 years.

I'm sure that's true depending on where you get parts from but a cam from the same year also? It will be interesting to see what's in the other engine

That adds a little complexity to it. Sorry man.

Was this a solid roller cam engine?

Hydraulic roller cam. I have been told that once in a while there can be a "bad batch" of parts that gets by quality control. I don't think that is the situation here as the engines have more than a couple of hours on them. I do not see that anything changed (something coming loose). I think if I had gotten more information from the builder I would have done any other required maintenance. As stated before I was planning on doing a compression & leak down test before winterizing this year. If testing valve springs was part of regular maintenance it should have been spelled out in a maintenance guide. Just saying. I was given no instructions at all.

Hyd rollers in a canted valve engine dont do all that well the more lift the worse it becomes. The pushrods must be shortend about .600 as the lifters are taller than flat tappes or solid rollers. The shorter pushrod increases the angle of the pushrod inthe set of the rocker and lifter. This increases issues with valve train geometry mostly do to side loads. There are hyd rollers with ofset pushrod seats in them but they still cause side loading issues. One might do well with a real mild hyd roller like just a bit over .500 maybe .550 or so.

Example Ford never converted to hyd rollers in a 460 because of pushrod angle

Turbo - I'd worry more about the machining of the lifter bores from GM. If these are not indexed true, the roller will have all sorts of bad forces going on.

IMHO.

I would wonder if your push rod length was correct also. Also wonder about the valve lash as someone said did it back off or maybe not correct to begin with.

I also heard that someone roller rockers were having issues as well but can not remember what brand. I will try to find out for an FYI.

Any builder that uses silicone and all over the place is an engine builder to avoid. Thanks for posting this info and who the builder was. Sorry for your bad luck. You seem very logical and not letting your emotions take over. Good luck

Manton makes a quality push rod as well.

Engines were picked up yesterday to get the one dyno'd for a baseline then rebuilt. Thinking seriously about going with solid rollers being the cams are getting changed. Making adjustments will not be an issue because I can remove the valve covers without removing the exhaust. Should have some dyno # soon. Am anxious to see what kind of power I really had.