Who's plates?

Was the mounting hole free of debris? How flat is the stud boss?  Are they new studs? Does the stud shoulder clear the hole?

Did you hold the plate in place while torquing?

So many questions.
Lol

Gt

No name plates. I paid $70 for push rods and plates. Hole was clean.  The boss is as flat as can be. Studs are not new. Stud fit through the plate easily. I did NOT hold the plate while torqueing on the others and had no issues. I wasn't even using my torque wrench yet on the one that broke.

Please don't take any of this offensively.

Chinese knock off plates with an inconsistent temper. The plate twisted under the load of the stud, you should always hold the plate while torquing, otherwise they twist and become misaligned. Sometimes they break. Once you have a new one, make sure to align the slot with the pushrod and open up any existing rod slots.

GT

Next set will be name brand. Do I still need to be so careful?

I would.

If I can get away with it, I use hardened washers between the head of the stud and the plates.

You really need to spend some time making sure the guides are adjusted properly. They will eat right through a push rod if done wrong. Unfortunately putting metal shavings all through the engine.

JMO

Gitterdone!

GT

Can u elaborate a little on properly adjusting guide plates? I thought it was a "set it and forget it" dealio.

Nothing is ever set it and forget it.

So once you have the plates installed, get your push rods and rockers mounted up (I do one cylinder at a time) and run them down to a rough lash. Rotate the crankshaft and witness both valves do a full stroke and monitor the pushrod clearance on the guide. I use a little white spray paint in the area of concern on all the pushrods. Not sure how many different ways there are of doing this, but betting it is a lot.

Look for hard contact on either the head hole or the guide plate and adjust accordingly.

I have never once done this and not had to screw with at least half is them.

Be sure to re-torque them as you go, I use a paint pen once they ate dome to mark them. You can go ahead and adjust the valves as you go.

The process really does not take too long. I figure about 15 minutes a cylinder.

Good luck.

There are some fairly decent videos on line on how to do this.

If I get time at lunch I will see if I can find a good one for you.

I'm elbows deep in an AC unit right now. (Literally).

GT

As you are doing all of that, if you have upgraded to higher ratio rockers, the push rod moves closer to the rocker fulcrum.  Pay particular attention to the push rod clearance towards and away from the rocker fulcrum.  If there is any binding, it will pop the push rod out of the rocker.  You will also want to verify that the push rods do not contact the head anywhere.  You might also have to tweak them just a little to prevent binding per GT's post.

Also verify that the roller tip of the rocker follows and remains centered on the valve stem.

When I set these up, I cut all them in half with a thin cut-off wheel and TIG weld them back together after.

Good luck,

Joe

Yes 3/8 pushrods. I'm using 1.7 to 1 roller rockers. Should I remove my intake for any reason?

Not until you need to.