Thread:

Broken head

Friend of mine sent me these pics of his motor. Any guesses as to what happened?







Sent from my iPhone using Tapatalk

Hope they're under warranty. Looks like a casting flaw to me. Might be something else, but that's my best guess from what I'm seeing.

RHS or Pro Comp?

Originally Posted by steelcomp

RHS or Pro Comp?

Pro-comps

Originally Posted by 28Eliminator

Pro-comps

There ya go.

Originally Posted by jimclauss

Looks like it was drilled, fixed and redrilled.

3rd pic. the big hollow void next to the stud hole??? still bouncing that of the inside of my head.. I thought it was just a casting void..

Originally Posted by 28Eliminator

3rd pic. the big hollow void next to the stud hole??? still bouncing that of the inside of my head.. I thought it was just a casting void..

It's where the stud hole goes into the intake port. They all do that to some extent. It's just that other heads don't rely on the roof of the port to take all that load. Plus, it's cheap aluminum. Add in some core shift and you get what you have. The BIG hole is just the roof of the port missing. You can sort of see it on the piece still attached to the stud. You can also see how thin things are right there.

Originally Posted by steelcomp

It's where the stud hole goes into the intake port. They all do that to some extent. It's just that other heads don't rely on the roof of the port to take all that load. Plus, it's cheap aluminum. Add in some core shift and you get what you have. The BIG hole is just the roof of the port missing. You can sort of see it on the piece still attached to the stud. You can also see how thin things are right there.

Oh yeah Duhh...

Just got a text from him. He said he called pro-crap, and they said send them some pics, it might be under warranty...

With Procomps, one of 2 things are going to happen if the cam is agressive enough to require pretty stout springs. You either pull the stud, or the boss lets go. Bad rocker geometry will tear a head up as well. Now you know why better heads have gusseting on the stud mounts, or the stud mount platform covers a larger area.

Also, if the aluminum is not virgin 356 aluminum you have no why of knowing what the alloy is. You can't cast heads, block or forge pistons from recycled aluminum. Anybody doubt the aluminum in Procrap heads isn't recycled junk? And the "heat treat" is a joke.



With Brodix RaceRite, Edelbrock E Street and /trickflow heads selling for the price they are getting, there is no excuse for buying this crap. But some people will never learn.

Originally Posted by 28Eliminator

Any guesses as to what happened?

Originally Posted by gn7

Bad rocker geometry will tear a head up as well.

Is it just the photo or does the underside of the rocker arm seem to have been riding on the lower radius of the rocker stud base? This could be just a clearance issue in the parts combination but more often than not it's a sign of poor valve train geometry as set up. Poor geometry will indeed side-load a rocker stud to hugely unnecessary forces working against the stud boss in the head; drag of the rocker against the stud isn't going to make things any better.

LO

If that isn't a machine cut Paul, then that rocker was rubbing the stud all the way to the closed valve end of the slot Which means the PR is way to short, which would explain why the rocker is low enough on the stud to interfere with the stud's radius.

Still shouldn't have broken the stud boss like it did. It's a piss poor design.

Originally Posted by steelcomp

Still shouldn't have broken the stud boss like it did. It's a piss poor design.

Agreed, the intake stud boss on Procrap heads is pitiful. You can see the thickness of the port roof and there is no additional means to tie the stud pad into the head. Even with perfect geometry, they won't take much spring pressure or a very agressive lobe. Terrible design.
But if the geometry is wrong, or in a bind, something is going to give. If not the head, then the stud or the rocker.