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Old 09-11-2017, 11:39 PM   #1
bs46488
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Need advice on fixing broken rocker stud on Big Block..

I'm looking for some input on how you would fix a broken rocker stud?

I just got my project truck back on the road and have driven 48 official miles. First 10 miles on the road the truck just died and i ended up pulling all the old MSD 6AL stuff and putting in a HEi. Then I have been fighting a power steering issue and finally resolved it. Drove the truck yesterday to test out the steering fix.

I was just cruising at about 30, then the truck started to sound like a misfire. Drove home and put it in the garage. Tonight I pulled the valve cover off and found this rocker in the wrong place.

Can I just replace all the rocker studs with some ARP, new adjusting nuts and hit the road?
Or would you do more? The rocker and adjusting nut with the broken stud inside of it was sitting in the valve cover, do I need to worry about metal debris? Or other damage?

The engine came with the project. I know it sat for 6+ years with the previous owner (and I've been working on the truck for close to 3 years) It's a 454 bored .030 over. He gave me a cam card from Crower. And under the valve covers are these fancy looking red rockers. Has a Holley 750 carb.

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Old 09-12-2017, 02:00 AM   #2
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Re: Need advice on fixing broken rocker stud on Big Block..

I doubt you have to worry about metal shavings. Take the piece of stud out of the adjuster and piece the stud together to check if any chunks are missing though.

Broken rocker stud could be a fluke but I'd want to make sure there aren't any other causes for it. Is the cam really high lift? I'd be checking to make sure none of the valve springs are going into coil bind. Also make sure the rockers aren't hitting the studs when the valves are open. Either of these would put extra force on the stud and could cause it to break.
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Old 09-12-2017, 08:15 AM   #3
homemade87
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Re: Need advice on fixing broken rocker stud on Big Block..

For just a quick check get the rocker at full open and be sure you can get a 50 thousands feeler gauge in there . If less that this it could be coil bind . If less there may be others that will do the same . Hopefully its just inferior studs . ARP would be a good idea anyway since one has broken .

As Overdriven has said also . Check to see if any witness marks on the rocker where it may be in contact with something .

Last edited by homemade87; 09-12-2017 at 01:35 PM.
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Old 09-12-2017, 09:59 AM   #4
Marv D
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Re: Need advice on fixing broken rocker stud on Big Block..

YUP,, there is some garbage parts that found their way into many a hotrod,, but you need to assume it's a quality part and find out WHY it broke.
Remember Murphys 2nd law of mechanical relationships..

"OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"

Check every possibility of WHY it broke before you assume it was simply a inferior part or you can end up with a huge mess.
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Old 09-12-2017, 11:52 AM   #5
mattfranklin
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Re: Need advice on fixing broken rocker stud on Big Block..

What is the lift? Is there any kind of part number or company marking on the rocker? Some rockers are made for higher lifts.
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Old 09-12-2017, 12:47 PM   #6
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Re: Need advice on fixing broken rocker stud on Big Block..

Thanks for all the input.

Marv D brought up a point I was curious about....WHY did this happened? And should I spend some more time/energy/money figuring out why and preventing in the future?

I'll dig through my project folder tonight and see if I can find any more info, part numbers, cam/lift specs, etc.

I didn't look at the rocker, I just looked to make sure the rocker, the adjusting nut, and broken off stud were still present. I'll see if I can see any scrapes or marks.

The only thing I know about those rockers is from what I learned from my friend Google. PSP is a chinese knock off of Scorpion rockers. They seem to be made in a 1.5 or a 1.65 ratio.
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Old 09-12-2017, 01:48 PM   #7
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Re: Need advice on fixing broken rocker stud on Big Block..

If it were mine I would pull the intake and look at the lifter and the cam lobe. Post better pictures of the spring and the rocker. Look like there are marks on the retainer.
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Old 09-12-2017, 09:29 PM   #8
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Re: Need advice on fixing broken rocker stud on Big Block..

A little more info....

I don't see any marks or contact on the rollers. Here is a pic of the damaged one, you can see some silver on the bottom that looks like the threads.



The rocker studs are 7/16 and just shy of 2"

The previous owner bought these rockers from a marine shop for $120, but no part numbers.

The cam is a Crower 01243, intake 284 with a .541 lift. Exhaust is 290 at .517 lift. The cam card says based on 1.7 rockers, but I can't identify mine.

I can not tell any info on the springs in the head
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Old 09-12-2017, 11:16 PM   #9
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Re: Need advice on fixing broken rocker stud on Big Block..

Damn. Sounds frustrating. Hope the kinks are all worked out soon. Agree that you need to discover why the stud broke. I would be going through and checking the valve lash and ensure the poly locks are set correctly. Unless other studs show sign of wear, you could probably get away with replacing just the one. Though a new set of ARP certainly not a bad idea.

1.7 is indeed the stock rocker ratio. Confirming what those rollers are is fairly simple using dial caliper or machinist scale. The image below should help:

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Old 09-13-2017, 01:49 AM   #10
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Re: Need advice on fixing broken rocker stud on Big Block..

Did a little more digging around and think it's time to consider plan b.

I pulled a good stud out so I could get some measurements. Then I noticed this stud is mared where the rocker sits on the shroud. Wondering if I need longer studs and shanks for the rocker to sit on?



Then I looked closer at the #1 cylinder spring and see two of the coils touching and look on the back side to see the spring is cracked. So now this is a whole new problem.

Since now the heads need to come off, I guess my plan b choices are:

1) aftermarket heads (didn't really want to spend that kind of $$ right now)

2) have my local machine shop rebuild the heads (most likely it would just make financal sense to do #1)

3) do a quick patch job myself with new studs and springs. Never done this and I don't have all those tools. My guess is $400 - 500 in parts and probably 2-3 months turnaround for me.

4) LS swap, just because that's what everyone is doing now-a-days.

Thanks again for everyone's help. I've learned a lot on a topic I have zero experience with.

Brian
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Old 09-13-2017, 07:05 AM   #11
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Re: Need advice on fixing broken rocker stud on Big Block..

Sounds like you will need a new set of springs to match that cam. I would pull the heads and have them worked. Rocker studs come in different lengths and yo may need a longer one for that setup you have. Pull a couple and see how many threads are in the poly locks. Should be about a 1/2". Next take a look at the push rod length verses stock to see if for some reason it has a longer set of push rods in it. With a project you just never know. While apart look at the lifter and the cam in the cylinder that broke the rocker stud. Since you drove it some there is a chance it could have gotten beat up.
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Old 09-13-2017, 07:58 AM   #12
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Re: Need advice on fixing broken rocker stud on Big Block..

Quote:
Originally Posted by bs46488 View Post
A little more info....

I don't see any marks or contact on the rollers. Here is a pic of the damaged one, you can see some silver on the bottom that looks like the threads.



The rocker studs are 7/16 and just shy of 2"

The previous owner bought these rockers from a marine shop for $120, but no part numbers.

The cam is a Crower 01243, intake 284 with a .541 lift. Exhaust is 290 at .517 lift. The cam card says based on 1.7 rockers, but I can't identify mine.

I can not tell any info on the springs in the head
The one things I see is there is thread marks on the rocker from the stud . Could be the rocker was pivoting back on the stud and flexing the stud to the point of fatigue and breaking it . This may be the reason why it broke where it did . Could be the reason you see the mark on the stud as well . Take a closer look at it and see if this is a possibility .

If this is the case , could be from the wrong length push rods . Be a good ideal to check the wipe pattern on the valve .
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Old 09-13-2017, 09:27 AM   #13
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Re: Need advice on fixing broken rocker stud on Big Block..

Factory Stud, no telling how old or how hard it has been run. BBC are hard on them and rockers in stock form. Make sure you have correct installed height on springs. Most of the companies assume you are putting in hardened retainers and tossing rotators.
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Old 09-13-2017, 10:26 AM   #14
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Re: Need advice on fixing broken rocker stud on Big Block..

Does the motor have guide plates for the push rods? Are the rockers self-aligning or are they the kind that need guide plates? That's an issue for small blocks, but not sure if BBCs have the same problem.
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Old 09-13-2017, 11:50 PM   #15
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Re: Need advice on fixing broken rocker stud on Big Block..

Don't automatically assume that rebuilding your current heads will cost as much or more than new aftermarket heads. Most will say that it will but that is not the case in my area. Check with your favorite machine shop first.

Quote:
Originally Posted by bs46488 View Post
Did a little more digging around and think it's time to consider plan b.

I pulled a good stud out so I could get some measurements. Then I noticed this stud is mared where the rocker sits on the shroud. Wondering if I need longer studs and shanks for the rocker to sit on?


Then I looked closer at the #1 cylinder spring and see two of the coils touching and look on the back side to see the spring is cracked. So now this is a whole new problem.

Since now the heads need to come off, I guess my plan b choices are:

1) aftermarket heads (didn't really want to spend that kind of $$ right now)

2) have my local machine shop rebuild the heads (most likely it would just make financal sense to do #1)

3) do a quick patch job myself with new studs and springs. Never done this and I don't have all those tools. My guess is $400 - 500 in parts and probably 2-3 months turnaround for me.

4) LS swap, just because that's what everyone is doing now-a-days.

Thanks again for everyone's help. I've learned a lot on a topic I have zero experience with.

Brian

All Mark IV big blocks come with pushrod guide plates. Most come with 5/16" pushrods, but performance big blocks usually have 3/8" pushrods.

Quote:
Originally Posted by mattfranklin View Post
Does the motor have guide plates for the push rods? Are the rockers self-aligning or are they the kind that need guide plates? That's an issue for small blocks, but not sure if BBCs have the same problem.
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Old 09-19-2017, 11:31 AM   #16
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Re: Need advice on fixing broken rocker stud on Big Block..

Never saw the head casting number in the thread(might've missed it). Some are more desirable than others. That would be another determining factor as far as keep/rebuild or replace. Sitting for 6 years isn't very good for valve springs..... some are compressed.
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Old 09-19-2017, 12:33 PM   #17
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Re: Need advice on fixing broken rocker stud on Big Block..

"Sitting for 6 years isn't very good for valve springs..... some are compressed. "

Good point. That is why I always tell customers to back off the rockers when letting it sit. Plus it closes the valves and helps prevent humidity from entering the cylinders. Funny how many will spend big time & money on an engine build for their rod, then leave it on a stand for years while getting the chassis & body together. Building the engine should be left for last. In my mind anyway.
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