Weekend 632 Carnage :(

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rl

Beautiful ride, and great looking engine too.

Not sure what caused breakage - valvetrain instability of some sort?

Looking at the rocker picture - looks like the rocker arm needle bearing is getting hot.

Mt first thought is: Why save a few $ and use Comp rocker arms? For such a large investment I would be using a rock solid
rocker arrangement. At minimum  Crower stainless rockers - or a small step up in cost to T&D, Jessel, or WW.

Just my opinion of course.

Thanks for the kind words.  I was advised that the shaft rockers were prone to pulling head studs out on the A460 head which is why we chose these “ultra” rocker arms with a stud girdle. It wasn’t to save money (as clearly valve train isn’t a place to save money and I spent the coin to put Titanium intake and exhaust valves in) . These rockers have 157 passes on them and while one broke... upon tear down, we noticed another was on the way with a crack (hence the pictures of the 2 different rockers).

Maybe the shaft rockers have improved (or been updated to solve this problem) since this this motor was built I’m hopeful some of the experts will chime in and offer some thoughts.

Trent

Lots of black and blue. Was that rocker getting oil?

Hi Lem,
I checked the lash in the morning and everything was ok then (I’m pretty fussy about checking the valve train as I know how sensitive it is and what a mess it makes when it goes bad). I only made 2 passes and broke on the second pass.  I saw the heat too.  The trunnion had oil in it as did the roller.  I should have been more clear... there were 2 broken rockers in the pictures... on was broken right off at the bottom and the other rocker is cracked but not broken (see the pictures) it is still intact and rolls fine.  It’s the base that is cracked.  Thoughts?

Was this the 1st two passes on the rockers?

They look to be the 1630-16 rockers or are they the 1830-16?

The cracked rocker shows heat on the bearing too.

I saw the heat on that one too. These rockers have 157 passes on them and have worked flawless up to this point. I’ll have to check the part numbers on the rockers. The lifters are ISKY red zone that I had converted to bushings. The have 62 passes on them.

Does the pushrod seat in a cup formed in the body or is there a steel insert like an aluminum body rocker?

I think I see the # on the rockers......1838? Same as 1830 but, 1.8 ratio.

2.000" installed height on the springs, or? What is the seat and open pressure on the springs? What camshaft lift?

c.evans wrote:2.000" installed height on the springs, or? What is the seat and open pressure on the springs? What camshaft lift?

What does that have to do about the black/blue on the rockers?

My guess is the valve head let go first backing the carnage up the valve train. The blueing shouldn't have happened that quickly, so likely this just forced by the failure (but eventual). The valve coming to an abrupt halt is going to play hell on that small cross section under the trunion.

You could be right.  #1 exhaust was the broken rocker (the one with the stud still in it).. upon tear down I discovered #3 exhaust rocker was cracked badly but not broken (see pictures above the one without the stud in it was from #3)

The other rockers look like they’re not centered on the valve stems. Hard to see in the pics but looks like tapered push rods? Which guide plate are you using? Nothing wrong with stud rockers but I really like the shafts I’ve ran.

Trentrent wrote:Thanks for the kind words.  I was advised that the shaft rockers were prone to pulling head studs out on the A460 head which is why we chose these “ultra” rocker arms with a stud girdle. It wasn’t to save money (as clearly valve train isn’t a place to save money and I spent the coin to put Titanium intake and exhaust valves in) . These rockers have 157 passes on them and while one broke... upon tear down, we noticed another was on the way with a crack (hence the pictures of the 2 different rockers).

Maybe the shaft rockers have improved (or been updated to solve this problem) since this this motor was built  I’m hopeful some of the experts will chime in and offer some thoughts.

Trent

how many passes before you take a look at your rockers, the one that is broke ran for a while broke.

who said shaft rockers pull the bolts out, silly. If you dont want shafts use a set of harland sharps

I only had 2 passes on the rockers after checking the lash.

Valve guide clearance?

Very sorry to see your carnage, I've been there via broken spring. I've run Jesel shafts rocker set up on early TFS A Head and T&D on the 3X version, with zero issues with the shaft stand attachment bolts on either. 100's of passes on both engines, 10's of thousands of street miles on each as well. 3X has deeper stud bore and threads. Jesel stands pair intake and exhaust per cylinder with a single bolt, while later 3X T&D has single long intake stand across 4 cylinders with exhaust stands attached with bolts thanks to input from Lem, Charlie and others on here to TFS. Expensive change, but worth it in terms of stability and easier valve train maintenance, and checking.