Rocker studs snaping

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holic_77

holic_77

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I've got a new rebuild 360 Mag .030 over with 40+ miles.
Edelbrock stock heads. Comp cam 220 276 290 .547 .544.
Push rods were measured before hand and got Crower 6.950.
Speedmaster 1.6 roller rockers

Broke a stud a few days ago while driving under 2k RPMS #2 intake. Replaced and drove it easy for about 38 miles.

Today I broke #5 intake after start up and idled up at 1500Rpms.

Are the rockers walking off? If that's a thing or any suggestions?

Stud 2.jpg


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image1.jpeg
 
I would contact Mike @B3RE and take a zillion pictures and see what he thinks. What did the rocker sweep on the valve tips look like? I see a mark on that broken stud. Look for a corresponding mark on the rocker that came off it in the end of the slot. Could be reaching the end of the slot and contacting the stud snapping the stud off.
 
Did you check the guide plates and how they affect the rocker geometry? In your picture above of the #1 intake looks screwed bias to the from of the motor. The rockers should not pivot on the stud and may be twisting the stud and snapping it.
 
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RustyRatRod said:
I would contact Mike @B3RE and take a zillion pictures and see what he thinks. What did the rocker sweep on the valve tips look like? I see a mark on that broken stud. Look for a corresponding mark on the rocker that came off it in the end of the slot. Could be reaching the end of the slot and contacting the stud snapping the stud off.
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No I’m not sure.
 
dano said:
Did you check the guide plates and how they affect he rocker geometry? In you picture above of the #1 intake looks screwed bias to the from of the motor. The rockers should not pivot on the stud and may be twisting the stud and snapping it.
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No, I’m not sure
 
dano said:
Did you check the guide plates and how they affect he rocker geometry? In you picture above of the #1 intake looks screwed bias to the from of the motor. The rockers should not pivot on the stud and may be twisting the stud and snapping it.
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They're both horribly out of alignment.
 
holic_77 said:
No I’m not sure.
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Well how bout actually looking and see what you see? Post pictures of the end of the rocker slot and let's see if there's a corresponding witness mark.
 
Yup. The edge of that slot on the roller side right there on the left is mashed flat. It's hit the rocker stud. See it?
 
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I'm no saying the OP did this, but a racer that we knew a few years back cheaped out on the studs using over the counter stuff. He ended up with a similar problem. We directed him to Harland Sharp to clear up his problem.
 
Demonracer said:
I'm no saying the OP did this, but a racer that we knew a few years back cheaped out on the studs using over the counter stuff. He ended up with a similar problem. We directed him to Harland Sharp to clear up his problem.
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Thanks. The studs came with the Edelbrock heads. I could go for some ARP. Or HS
 
I did cheap out on the rockers though. I got all this money into this build and then I went for the cheapest rockers.
 
I have never used stud mounted rocker arms but I am wondering if the pushrod can get through the slot straight when looking at the picture in post #8. Looks like the push rod hole is partially blocked by the guide plate. Could the pushrod be pushed at an angle and putting pressure on the side of the stud or smashing the rocker as RRR mentioned?
 
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I’ve never used the Ede Magnum heads....... so I have no idea if this is typical with those or not, but that rocker alignment to the valve tip is pretty bad.
That’s usually a guide plate problem.

Regardless of what else you do, get some ARP studs.

FB41083B-A0E1-461C-85CB-40DA5D6CE577.png
 
Hyd Roller?

Pull the pushrods and look for witness marks where they pass through the holes in head.


Could be levering against the head, pushing at the edge of your adjuster cups.
 
There was an article a couple years ago about building a Magnum based engine with EQ heads. That article mentioned changing to a different rocker arm because they found binding, which sounds the same as this situation. You will need a set of adjustable guide plates to center the rollers properly over the valve tips (front to rear) but that won’t fix the breakage. You already showed the witness marks on the rocker arm as RustyRatRod suggested.
I have the same Edelbrock heads and I am ordering adjustable guide plates too, since mine have poor alignment as well. But rocker arms have no witness marks like yours.
Build Your Own 455HP Pump-Gas Magnum V8 For Around $4,000!
 
I’m trying to stay positive when I’ve spent over $10,000 on this rebuild when it’s only a couple hundred bucks more to keep it going. my daughter loves this car and that is the adventure of it.

8465A7F8-AC5C-4BD7-BA9E-C88F42EC2C99.jpeg
 
The daughter has the look of "Dad is going to let me drive this one day" LMAO!
 
To me, this look like you need to remove the rockers, loosen (replace in some cases) the studs so the guide plates slide side to side, reinstall the rockers to snug on the valve tip and move the plate to get the rockers to line up. Do not be surprised if you need to slot the plate holes that the studs go thought to get enough movement side to side to line it up. Stud height and push rod length may need to change to adjust rocker geometry so I would mock up what you have to see if they are the correct length.

This get fun on a canted valved heads like Fords 335 and 385 family and Twisted Wedge heads that have compound push rod angles. A lot of guys use a light weight valve spring to do the mick up.

The problem is who knows what Edelbrock used for rocker geometry to determine the stud length they send. If you took 4 to 5 Magnum based rockers from different manufactures non of them would be the same (unless they are rebranded).

Looking at how the studs broke it look like the rocker was twisting the stud until it broke.
 
holic_77 said:
I've got a new rebuild 360 Mag .030 over with 40+ miles.
Edelbrock stock heads. Comp cam 220 276 290 .547 .544.
Push rods were measured before hand and got Crower 6.950.
Speedmaster 1.6 roller rockers

Broke a stud a few days ago while driving under 2k RPMS #2 intake. Replaced and drove it easy for about 38 miles.

Today I broke #5 intake after start up and idled up at 1500Rpms.

Are the rockers walking off? If that's a thing or any suggestions?

View attachment 1715771317

View attachment 1715771318

View attachment 1715771319
Click to expand...

I'm stickin with my rocker arm to stud interference theory. The witness marks are THERE. Also, no one's picked up on this. You're running Magnum heads....so I ASSUME those are 1.6 rockers? If so, you need to recalculat the lift on that cam. I just "bet" that's too much lift for those rockers you "cheaped out" on.....your words. Not mine. lol
 
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