Thanks, It does look like it is sitting below the head stud. I'll go check it out

Right now the car is in the trailer stored at my friends house. I don't have room at my house to park a trailer.

I did get my 4-post lift yesterday, now I just need to assemble it.

Have you checked the depth of the studs? Normally studs are made for a depth of appx 1,5 - 2 x diameter. That would be too short and put stretch in the material to high, where the X-section is too small. Check this!! Cast material does not take much stretch, so it is normally designed to avoid it, and go compressed instead. If you let the studs or bolts go far down, you would be better off. I have same heads, and my bolts go a LONG way down in the heads. That would prevent shuch things from happening. Normally such a failure should strip out the threads instead. My

The studs go right down to about the base of the cracked off part. The studs do not go into the head below the point where the rocker stand cracked.

I could not find any close-up photos of the area that I took of the heads when doing the mock-up, but I think that I noticed a small zig-zag pattern in the aluminum around the top part of the rocker stand where it is now cracked, but I thought it was just some scratches from where that area was machined.

Anyhow I will have to take a close look at the other head too, and see if it has any signs of cracking?

So you know the answer. Too short studs, along with heavy springs.

I measured my MW victors, and they have 1,13" thread engagement. I would recommend you to switch to bolts with full depth (allow one thread for tightening), you could cut to fit, or adjust them with washers on top.
The center pedestal is only 3/4" wide, and in addition the center and two outer are helicoiled, which takes even more away from the X-section.
You need to take away the rest of the helicoil, open the hole so it can be welded all way down, and drill/thread again (preferably without helicoil). It is simple to drill/thread using a rocker shaft as fixture, and the same for fitting the pedestal with a round file, after welding.

If wrong shims (flat/even thickness) were used the pedestal would split along the rocker shaft centerline, I had an RPM head from a customer with that fault (very thin due to the helicoil). Simply filing the shims sharp, and pressing them in iron heads makes them good, to avoid the cracking.

So, with some work and small cost you can redo your head, and switch to full thread bolts on all rocker pedestals will cure the problem.

For assembly oil the threads, and release the adjusters fully, turn the engine if needed to avoid bolting down against full lift.

Hope it works out for you, wish you good luck!!

Best regards
Oyvind Mostad / Norway

Good job spotting the broken off part!
The rocker shims were from Hughes Engines, and they claim they are tapered to fit correctly?
I have not decided which way I want to repair the head. I could call Edelbrock and see what they say, but the stands from Billet racing parts look nice. I need to ask them how high they sit, or if they have extra material so I could set the stands at the height I want (so I do not need to use the shims.)

I also think that if I have to disasemble the heads to machine the stands, that I will cut the valve spring pockets 0.050" deeper to get the 2.00" install height I originally wanted. This will reduce the spring pressure about 25# too.

I think I may still have a set of those Max Wedge type stands if you need them..

I'm not using them..

I'll check..



Chris..

Thanks for the offer Chris. If you find them, can you post what the height from the base to the bottom of the shaft hole is? I'm tring to figure how high they are? Also, I will need to check the rocker shaft bushings. The T&D rockers use a smaller diameter shaft with a bushing to bring the OD up to the stock diameter at the hold downs.

Ok I think I finally got the rocker gear sorted out (I hope?).
I had the stands machined off and used the Billet Racing Parts.com Max Wedge Stands. I asked to have them set about 0.050" higher, but when I got the heads back the rocker stands were about 0.200" higher. With lash caps on the valve tips the sweep pattern looked OK, so I had to get longer pushrods.
I got the valve train back together and the engine running, but no oil to the front rocker arms.
The machine shop used standard 3/8" Grade 8 bolts, but the T&D shafts are very thick walled (small oiling hole), so I had to grind down the bolt diameter a bit for oil flow through the rocker shafts. Engine was running OK, and allowed to warm up / run for about 20-minutes.
I then reved it up, and BANG! it started making bad noises again. Pulled the valve cover and found the pushrod for the center exhaust rocker out of place again (This is where I originally started..)
Removed the rocker shaft, and found the Heli-Coil halfway pulled out of the head (only a 1/2" long insert.) This is where the head originally broke, and the machine shop had this milled further down than the rest of the stands and used a spacer to make up the height difference, but did not make the bolt hole deeper and used the original length bolt, so the bolt only caught the first few threads of the heli-coil.
After some research, I decided to repair the bolt hole with a "Time-Sert":
http://www.timesert.com/index.html
This is like a threaded bushing and stronger than the heli-coil type insert. I also chose to use a stainless steel 3/4" long insert for the repair. I then used a longer bolt for plenty of thread engagement.
Fired the engine up again, and reved to 6,500+ RPM several times. So far the repair seems to be working good. Now if it just warms up so I can drive the car....

Anyone else use these "Time-Sert" repair kits?
They are pricy, but seem really nice of you need to fix a highly loaded bolt hole.

Never used Time Serts before but it looks like a good system. I use Keen Serts,there the ones with the 4 pegs that lock the threaded piece in. You have no mention of if you called Edelbrock. I hope that fix's your problem, a bound up valve from a broken valve train isn't going to be pretty.

Could that have happened from torquing the stud down in the hole? I believe studs are meant to be hand tight. If its tightened down in the hole the wider part of the stud after the threads will try to spread the hole thus causing a crack. I did this with a main stud one time. Just a thought.

I've used the time-serts on stripped out intake manifold and cylinder head exhaust bolt holes. Prefer them over helicoils, especially on the B/RB heads because they seal better on the exhaust (coolant). They are the preferred method to repair the mid-2000 Ford 5.4 engines that launched the short reach sparkplugs from the cylinder head.

I think the rocker shaft shim caused the shaft mount to crack. The original hardware from T&D used studs.

I have worked on Edelbrock heads that had Hughes shims that were flat and not tapered, they made the support crack but they did not fall off or fail because the longer bolts still keep the parts together. These RPM heads were helicoiled which took even more off the goods making cracking very easy to happen... Check the stands by the exhausts, they are very skinny!! I filed the shims with taper, and bolted together, still works OK.
BTW, your solution now is similar to what is used in aircraft parts, I have a huge carburator from an R1820 Wright radial engine , and it has steel inserts in all threaded holes, to prevent pulling alu threads.
Hope you have cured the problem with the long bolts. Check that all your bolts or studs engage deep into the head!
Good luck!

I have seen stock Chrysler 3.3/3.8 V6 heads break the rocker stands like that. I'm sure that's not a harmonic or spring pressure issue. These heads are sand cast and casting flaws happen. I'd fix as stated above with the rocker stands and not give it a second thought.

YES your shims caused that to happen.

think for a minute.

your shaft is .875 dia the head is cut for the .875 dia (.4375 radius)

you added .020 shim adding .040 to the dia.

so what you did was PRESS a .915 dia into a radius cut for a .875 dia

It is fixable

Bob

x2

here is a little CAD drawing which shows the problem with parallel shims: