Broken rocker stud?

[Chris bugster]

The engine is an 1835 with Scat c35 and Scat Pro Comp 1.25 rockers and Aircooled.net Ali pushrods. It has h/d single springs only.
Question is- Could possible valve float cause a broken cro-moly rocker stud? One broke after a long high speed run.
The engine has done one year or street driving and some racing.

[spanners]

That's one thing I've never seen break even when Pistons hit valves in blow ups, I would change the lot, it can only be a bad batch thing, you don't even have mad spring pressures to have stressed them, a loose nut may be possibility, that would give the stud a high frequency work out, but you would know yourself if that was an issue, you would have,  or SHOULD have heard the valve clatter.

[Jim Ratto]

what torque are you using to bolt rocker shafts down?

Also, the rocker stands/shafts usually only go on "one way" but it's easy to miss that and bolt stands, and/or shafts on "upside down", which may injure, nick, mar the rocker stand stud, creating a stress riser that leads to a stud breaking. I've done it a few times, just a few weeks back on my chromoly HD studs, after a few 7500 stabs, one broke. (I recently cranked spring pressure up in my car too).

Don't go past 18lb-ft.

[Berger]

Yes, it can be caused by valve floate. Done it twice..

[Chris bugster]

Thanks for the replies guys
All the parts were assembled correctly with the correct torque and the only doubts we had was regarding the springs and if the singles would be enough to control this valvetrain