Could the pushrod be getting into them when it flexes? Seems unlikely but you never know?

Off the top of my head I’d say...... you need better lifters.

But, I do have a question......
Lifter bores are dry on the Indy block unless you get the lifter oiling option........ does your block have that option?

If you’re running dry lifter bores, you’re not adequately oiling the lifters.

IMO, the Sportsman lifters are going to be marginal with 900lbs open load.

If the lifter bores are dry I’d talk to Isky and see what they recommend for that application.

From what I’ve read, the H-11 style springs don’t seem to have the high rpm stability that some of the more modern stuff does.

At 7K........ you could probably run less open load too.
What’s the lift?
Is the cam anything weird?

Also, if it’s a std core size cam........ with that spring open load, the cam could be flexing, adding another variable to the valvetrain tuning...... which could be causing some strange things to occur.

ok well
Comp Cams has pulled those lifters off the market. If it is an Indy block, was it drilled for Hyd oiling when ordered? IF not the bushings are failing due to a lack of pressurized oil. I have also seen the tie bars rub a lot on the ends of the blocks that can cause binding. With that much pushrod and spring pressure I would step it up to a 55mm or bigger cam. The cam could be deflecting under load causing some serious gyrations in the valve train. Rubbing pushrods and making sure that the pushrod has the correct ball on it to mate to the lifter cup.
Just a thought or two.
Todd

But why is the button the weakest link? All it controls is tappet rotation, nothing to do with spring load.
Are you sure that the tie bar still has slack at the extreme end of travel in the gallery at the actual lobe positions? If the linked tappets are moved in tandem, does the link bind?

I suppose another question might be.......
Are you sure the broken tie bar is the cause of the problem, or is it a casualty after the bearing fails and the wheel gets smashed?

I suppose if the high lobe lift does in fact use up all of the slot in the tie bar, it would answer that question.

The only bushing I can imagine holding up without pressure fed oiling are the Isky Speedway redzones...... but you should talk to them about it and be sure to tell them the lifters won’t have any oil feed to the bushings.

You might consider a little milder intake lobe as well, with a little less lift.
Just let the boost do the job.

A 273@.050 lobe that’s .521 lift has some pretty fast action.

If it’s a Comp, I’d be curious to know the lobe numbers on that cam.

I also agree with Todd about stepping up to a larger cam core if what you have is still using a std cam core.

You would really be helping out the lifter pressure angle situation, especially with that much lobe lift, by increasing both the cam core diameter and the lifter diameter(and the accompanying bigger wheel).

Obviously it’s easy to sit at the keyboard and “armchair quarterback” the situation after the damage is done...... but IMO, your exact combo........ very high lift lobe, high pressure angle, high open spring load, Sportsman lifters, no pressurized oil to lifters........ that’s a recipe for failure.

I guess at this point one might ask........

How much power would you be willing to give up to make that problem go away....... or conversely....... how much would you be willing to spend to greatly reduce the chances of it happening?

I would very carefully inspect all the undamaged lifters for clues as to where the failure starts.

Thoroughly clean the lifters to get all the oil out of the bushings, and check to see if there is any discernible vertical play in them.
Look all the link bars over really good with a magnifying glass.

You might see the likely point of the original failure.