0Randy@DRM

Modified engine (not by us). It ran very strong for a long time, then... Heads are not ported. Intake side. Spring pressure isn't a crazy amount either. Have you guys been seeing this?

satans csex

Did you check if the bolt is the right one? it might have been a wrong bolt and a shorter bolt means it wont grip in the more meaty area. Or they might have torqued too much. Or that rocker is very loose and it had too much play which caused more impact. or it was simply a defective cylinder head......or the world may never know haha

ole

Or that rocker is very loose and it had too much play which caused more impact and heat look around the bolt its in the color

C5 Frank

That is a crazy one!!!

LFZ

thats what I was thinking....thats messed up.

Frans96ss

Yes i have actually seen a car do something like that except it broke into the intake port. Stock head also. Manley nextek springs and a 242/254 cam. It did it in the EXACT same spot on both heads. Right through the GM casting mark.

0Randy@DRM

Thanks, I'm glad that we aren't the only ones to see it. I have no idea what camshaft this car has. The pulling out the intake port was kinda rare, but a known issue if guys got too crazy porting the roof of the intake.

Rocker was tight, right bolt and everything else seemed to be in-line.

Randy

383vett

Nothing that a tube of JB Weld couldn't handle.

Z06LINK

JB Weld isn't going to fix that.

0Randy@DRM

I was thinking hot glue

bowtiguy

I thought the stock bolts threads extend all the way to the tip of the bolt, 3 heads swaps will familiarize you with parts as you are cleaning them prior to re-install.

I've got some great pics of my failed INA bearings ( at work)

another reason I'm glad I went smaller with my cam.

jerseydrew

nah you need something stronger like gorilla glue.

FASTBLUEZ06

Could that be welded to be able to use the head again?

CanadaGrant

Could it be a flaw in the drilling and tapping of the head? It looks like scuffing on the rim of the bolt as if it was bottoming out in the head causing it to separate. In other words, maybe the hole wasn't quite deep enough.

0Randy@DRM

If the head wasn't in production, or was huge money, then I would try to weld it back up. Sence the head is everywhere, it's not worth the risk of coming apart again and causing more damage.

Randy

quickc6

I secod gorilla glue .

Gannet

Very interesting. It would be interesting to know if your failure and the one Frans96ss saw were on the same cylinder. It might also be interesting to Zyglo the rest of the stands on the failed head and, if the customer is up to the guff, the unfailed head.

Joe C5

I like this one (defect) or oil left in the hole when it was previously reinstalled (oil gets hot, expands, bing)...

GTABurnout

Castings are brittle (ewe all knew that) all it would have taken was a small casting flaw or even a void in the casting to cause this. Notice the angle on the corner closest to the camear that tells me the casting falw was aroiung that point at the corner the casting cracked then in typical Aluminum Casting brakes the brake followed a stright line basted on the last thread of the bolt.

But what do I know I only work with missiles not engines....

J HEBERT

Any signs of prior valve-float? Harmonics can be at work here. I was running stock modded H.S. rockers and broke a rocker bolt......but was able to drill/easy-out the bugger and I put the shaft units back on. BTW, 420# open spring pressure here, but I had an fast ramp-rate cam at the time. My head did not do that, but they are not stock castings.....