Rocker Stud Snapped!! What Roller Rockers In Photo

90silverstang · Feb 7, 2011

The roller rocker stud snapped on the exhaust valve. The exhaust valve was not opening and what a banging noise through the intake. I guess when the intake valve opened the the exhaust gases went through the intake and back fired. What causes a stud to snap. The poly lock was unbelievably tight! I cant get the broken stud out of the poly lock.
Also can anyone identify what roller rocker I have? It has a sledge hammer insignia, color is red
350, 3/8," 1.6
350 must be max spring pressure, 3/8 is stud size, 1.6 is rocker ratio,

On the bottom it reads SPL08
Could not post photo
Thanks

srtthis · Feb 8, 2011

email me the picture and i will post them

dtillery798@gmail.com

Noobz347 · Feb 8, 2011

Lots of things can cause a stud to snap. I once had a brand new stud break in a new motor. I've since replaced them all with ARP studs and haven't a problem since. Likely, the one that broke had a crack inside of it that weakened it enough to break. Considering all the impact these things go through even at idle.... I'd probably just replace them all if you've got the time and inclination.

90silverstang · Feb 8, 2011

srtthis said:
email me the picture and i will post them

dtillery798@gmail.com

srtthis,
I emailed the pics to you, thanks!

srtthis · Feb 8, 2011

never seen any with a hammer on them... but the "350" etched on them makes me think they are for a SBC

90silverstang · Feb 8, 2011

It looks like a quality rocker, and the 350 I think stands for max spring pressure.
On the bottom it reads SPL08 ??

BK_CAULEY · Feb 8, 2011

Thats a war hammer rocker and thats just a part number. not a chevy rocker.

90lxcoupe · Feb 8, 2011

looks like the lock was about bottomed out on the stud

90silverstang · Feb 8, 2011

OK-- I found out the brand roller rocker-- it's a PRW. Looks like a quality rocker, anyone running them?
Also found out the studs are not ARP's, Speed shop said I should go witha longer stud so the poly lock screws down on more threads.
One other thing, I purchased a adjustable push rod to check roller tip geometry. Its a comp cams
7905-1 The speed shop guy says if I rotate the engine with the adjustable push rod in place it will break because its thin walled.. How can you check the geometry on the roller tip to valve stem if you can't rotate the engine??? Sounds fishy to me

BK_CAULEY · Feb 8, 2011

you have to use a special valve spring. its used for testing only and is real soft.

90silverstang · Feb 9, 2011

More issues, found a bent pushrod. See Pic!

Well was checking roller rocker geometry and I couldn't line up the roller rockers on cylinder#5 from side to side with the guide plates. I tried to spin the intake pushrod with my fingers but I noticed it was binding. Look at the pic below. Now I'm hoping no damage was done to the intake valve. This all happened because the exhaust rocker stud snapped. so the exhaust valve was staying closed through engine revolution. I think the pushrod bent from backfiring through the intake valve while it was opening. Will do a compression check. What do you guys think?

oldfox · Feb 9, 2011

No,, I think the valve needed to "Kiss" the piston. But it may not have damaged the valve.
I have done over revs and bent push rods and not damaged the valves before.
Please post after you do a compression check and let us know.

90silverstang · Feb 10, 2011

will do

90silverstang · Feb 10, 2011

oldfox said:
No,, I think the valve needed to "Kiss" the piston. But it may not have damaged the valve.
I have done over revs and bent push rods and not damaged the valves before.
Please post after you do a compression check and let us know.

I have never overevved this motor, the exhaust rocker stud snapped.

I checked the compression on #5 cylinder. It reads good--- 180psi compared it to #1 cylinder, same result. I called Dart heads, they said I should pull the head and inspect the valves. Do I need to pull the head? I will try a leak down test as well.
What should I do?

jerryD · Feb 10, 2011

i took an old stock pushrod and cut it, then threaded it, and put all thread in it to make an adjustable push rod. i bought the trickflow adj push rod, and it was soft and wore on my guide plate when doing my checking. but i did this with regular valve springs and a hydro lifter made to a solid. reverse those first two sentences.,

at minimum do a leakdown test. the stud that snapped is also connected to the rocker which is connected to the pushrod which is also connected to the valve. the whole train of parts has somehow been subjected to extra stress. next thing in line to check is the valve. also check the lifter(either through pushrod hole or pull intake) to make sure it didn't come out of the hole like mine did when i had an issue. i had at least two bent valves and my pushrods were about as bent as yours. my pushrods where edelbrock FWIW. i now have chromeoly(not by choice) cause of the specific size for my app.

diusclaimer: im a little intoxicated, but im still coherent to know what im talking about.

90silverstang · Feb 11, 2011

jerryD said:
i took an old stock pushrod and cut it, then threaded it, and put all thread in it to make an adjustable push rod. i bought the trickflow adj push rod, and it was soft and wore on my guide plate when doing my checking. but i did this with regular valve springs and a hydro lifter made to a solid. reverse those first two sentences.,

at minimum do a leakdown test. the stud that snapped is also connected to the rocker which is connected to the pushrod which is also connected to the valve. the whole train of parts has somehow been subjected to extra stress. next thing in line to check is the valve. also check the lifter(either through pushrod hole or pull intake) to make sure it didn't come out of the hole like mine did when i had an issue. i had at least two bent valves and my pushrods were about as bent as yours. my pushrods where edelbrock FWIW. i now have chromeoly(not by choice) cause of the specific size for my app.

To clarify the problem with my engine:
1. The Exhaust rocker stud on cylinder #5 snapped.
2. When this happened the exhaust valve did not open when the engine was running, so piston comes up to tdc, spark to ignite A/F mixure, piston goes to Bottom, exhaust valve never opens when piston is coming up compressing the Ignited A/F mixture again, on the way down the intake valve opens and the A/F mixure explodes through the intake, so when the intake valve is opening its being detonated by the ignited A/F causing the bent pushrod on the INTAKE valve.

90 lx convert · Feb 11, 2011

Not sure I follow. You think the intake valve opened and the backed up exhaust rushing in detonated the incoming fuel charge? If that was the case the pressure wave would move on up into the upper intake tract away from the valve, correct? If so then how would the pressure moving away from the valve cause it to bend the pushrod? Anyway, before you put it back together I'd suggest some investigation first. I know it's a pita to remove the head but wouldn't it be worse to put it back together without checking and really hurt it? BTW a pushrod checker does have to be used with a weak spring. If you want to check geometry dab a lump white moly lube on top of the valve, use your regular pushrod, install the rocker, adjust it correctly and turn the motor over by hand. Remove the rocker and check the wipe pattern in the grease on the valve. Mike

Rick 91GT · Feb 12, 2011

You can most likely look at the witness mark on top of your valve right now. Otherwise use a sharpie to color the valve tip and use another pushrod and set it and turn it over.
you should always use a checker spring when checking ptv or geometry.

It is very common to bend a pushrod when a rocker loosens or breaks.

90silverstang · Feb 12, 2011

90 lx convert. said:
Not sure I follow. You think the intake valve opened and the backed up exhaust rushing in detonated the incoming fuel charge? If that was the case the pressure wave would move on up into the upper intake tract away from the valve, correct? If so then how would the pressure moving away from the valve cause it to bend the pushrod? Anyway, before you put it back together I'd suggest some investigation first. I know it's a pita to remove the head but wouldn't it be worse to put it back together without checking and really hurt it? BTW a pushrod checker does have to be used with a weak spring. If you want to check geometry dab a lump white moly lube on top of the valve, use your regular pushrod, install the rocker, adjust it correctly and turn the motor over by hand. Remove the rocker and check the wipe pattern in the grease on the valve. Mike

I have a question checking valve geometry, Do you check each roller/ valve stem pattern on all 16 valves? When measuring the pushrods, do you order pushrods individulally for each valve?

Butterfinger · Feb 12, 2011

Rick 91GT said:
You can most likely look at the witness mark on top of your valve right now. Otherwise use a sharpie to color the valve tip and use another pushrod and set it and turn it over.
you should always use a checker spring when checking ptv or geometry.

.

Instead of a softer checker spring? If one bolts up the heads with a solid lifter and the rockers torqued and the valve cups set ( 0 lash + 1/2 turn) then can't the engine be turned over by hand to check ptv clearance? I'm assuming that the hydraulic roller lifters will have to be used to check the rocler sweep across the valve stem though.

Rocker Stud Snapped!! What Roller Rockers In Photo

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