mrfixxall
 

the stock roller lifters are rated for .570 lift max!!! of the rockers wont get enough oil to them... also check the bottom of the rockers for binding at max lift,may need to massage them a little to keep from binding on the stud..

I have seen it more on Solid and when the rocker is too loose but if the initial adjustment is way off on a hydraulic I would imagine you could also break stress the stud!

Seems reasonable that you can crack the stud and have it fail at lower rpm.

Looks like there are some good ideas to pursue. Found anything yet? Broken spring is easy. Checking pushrods is easy. I would think that you would hear tapping if a rocker arm was loose, right? Also I would think that too tight a lash on the rocker arm would hold the valve open and you would've noticed a lot of problems before the stud broke.

My 502's with Crane hydraulic lifters floated the valves on the dyno at 5600 rpm, just a thought. Morel lifters didn't float up to 6000 (stopped the pulls at 6000).

If you were putting all the springs into coil bind you wouldve broke a lot of stuff before 200 hours.

Don't know about the lift issue with 496 lifters, definitely something to look at there.

Let us know how it goes.

Thanks. Where is the 496HO lifter max lift rating information available at/from?

Your experience is that a valve train with too much clearance can experience rocker arm stud breakage...............as apposed to the valve train being too tight as being the cause for rocker arm stud breakage.

Thanks!

Should know more Thursday.

My dyno pulls were with the same springs, different lifters.

Also check to make sure that the pushrods are the correct length, a long shot but it is part of the process.

Don't know about the lift issue with 496 lifters, definitely something to look at there.Yes but then why no problems of insufficient oiling for all those hours? Good point

rage i had a lifter go bad ,,,it knocked the push rod off the rocker arm,,,the hydraulic lifter would not compress at all,,,was told it could of broke the stud,,,in my case it didnt

mrfixxall
 

Sorry i didnt realize you had a newer 496 ho,i was refering to the gen 6 style lifters, you may want to check with comp cams and they could tell you.. on aanother note, your lifter adjustment is also critical as well..most hyvrolic lifter now a days have a pre load adjustment which means they can be compressed before it opens the valve..most people have their own way of adjusting hydrolic lifters and some set them to their max limits which is not good for the valve trane..a lifter can be comppressed a max of .100 1 full turn, i like to set mine at 0.25-.050 1/4-1/2 turn, this will allow a little cushion just in case your lifter shoud malfunction and fully pump up it wont go the full .100 and the valves wont crash into the pistons..

That is very interesting. Exactly how does a hydraulic lifter malfunction so that it would pump up its adjustment length and thereby hold a valve open against the valve spring preload?