What could have caused this broken valve spring?
The one thing that i notice is this. Every aftermarket spring i have used has a different lower spring seat and seal than that of a stock spring. The factory valve spring has the lower seat and seal combined which is what is still on your head from the picture, and they look old which means they werent replaced. It would not suprise me if those were stock springs. Any time you change a camshaft to anything other than factory. ALWAYS change to hardened pushrods and double springs. I never run anything without double springs. Aftermarket camshafts besides having increased lift and valve duration, also have increased ramp rates to achieve higher lift earlier, all of this is depending on the application. That is known as dropping a valve and it unfortunatly usually causes alot of damage. Your damage actually looks like it may be salvagable with a valvetrain replacement and head replacemnt. Good luck with your repairs. and i would suggest a new engine shop.And any reputable engine builder should have caught that, the machine shop just put the springs they were told to, most likely. Go through someone reputable.
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
Likes: 0
From: Troy, MO
From looking the valve springs assembly over more today, looks like the spring broke first. That let the valve float. Even is lock cam off the spring wouldn't break would it? There is a small gap between the locks but I don't know if that's in spec. Dropping the damaged head off tomorrow so Machine Shop can take more pictures to send to spring manufacturer. Any pictures of a correct lock assembly would be appreciated.
The gap in the locks is not my issue, that is normal. My issue is how far doen the locks are in the retainer. 9/10 times the locks should be flush with the top of the retainer. Do the locks come through the bottom of the retainer at all?
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
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From: Troy, MO
I will double check the locks in the morning. I am dropping a new head off tomorrow at the machine shop.
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
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From: Troy, MO
Spring ? Here is a better picture of the valve spring assembly. They all look similar to this. There is a .060 shim under the spring.
I don't have a way to measure the install height but I will discuss this spec with the machine shop.
What springs should be used with this cam?
I don't have a way to measure the install height but I will discuss this spec with the machine shop.
What springs should be used with this cam?
DO NOT I repeat do not take those heads to who ever set them up the first time. Unless my eyes are going out your springs are installed upside down. Again I am 99% sure your locks are not fitting in your retainers as well.
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TECH Apprentice
Joined: Jun 2009
Posts: 318
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From: Oklahoma
DAMN! TurboBuick is correct. That's not correct.
Please post who is the engine builder ( butcher) and who assembled ( butcher) the heads.
I'm sorry sir but you have been robbed. Happens all the time though and it's a shame
Please post who is the engine builder ( butcher) and who assembled ( butcher) the heads.
I'm sorry sir but you have been robbed. Happens all the time though and it's a shame
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
Likes: 0
From: Troy, MO
How do you know correct orientation? 
If it were my heads I would purchase new everything. Springs, retainers, seats (which are not on your head) and locks.
PAC-1218X(springs), PAC-R311(retainers), PAC-S111(seats) and PAC-L8114(locks).
PAC-1218X(springs), PAC-R311(retainers), PAC-S111(seats) and PAC-L8114(locks).
I had heard from an older racer that back in the day they used to run beehive springs way before anyone knew what we know about them today, but they ran them "upside down". The reasoning was that they could get more spring pressure from the larger OD while still fitting in the OEM 1.25" spring pocket. Unless you have been living under a rock, any competent machinist should now better nowadays.
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
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From: Troy, MO
This the the springs that I purchased, PBM3250 http://www.pbmperformance.com/store.php?catId=169. Since I didn't assemble how do I tell if these are the springs that are on the heads? Are there manufacture numbers or markings?
Last edited by donnie_19; Jun 11, 2013 at 03:47 PM.
You need a new machine shop/assembler. screw me once your fault screw me twice my fault.
They used bare bones everything.
Also check the connecting rod to make sure it is not bent
They used bare bones everything.
Also check the connecting rod to make sure it is not bent
Thread Starter
On The Tree
Joined: Dec 2012
Posts: 177
Likes: 0
From: Troy, MO
Stopped by machine shop and talked with owner tonight. All paper work and photo's have been sent to valve spring manufacturer to file a warranty claim. Will find out more info tomorrow.
This is the springs the machine shop used form PBM Performance. I have no way of verifying that these are the springs installed on my heads unless there is some kind of markings on the springs. Never once did I mention not to spend the money on using a good or better product.
http://www.pbmperformance.com/store.php?catId=169
This info taken from their web site. PBM 3250
The absolute BEST valve spring for the LS1 engine or SB Chevrolet.
•Conical design oval wire valve spring will fit factory retainer •Design delivers superior dampening
•Oval wire design allows higher valve lift & increased seat & nose pressures
•Ideal for hydraulic roller cam applications
Stock# INSTALLED PRESSURE OPEN PRESSURE COIL BIND MAX LIFT RETAINER Price Quantity
PBM3250
specs>> 110# @1.750"
This is the springs the machine shop used form PBM Performance. I have no way of verifying that these are the springs installed on my heads unless there is some kind of markings on the springs. Never once did I mention not to spend the money on using a good or better product.
http://www.pbmperformance.com/store.php?catId=169
This info taken from their web site. PBM 3250
The absolute BEST valve spring for the LS1 engine or SB Chevrolet.
•Conical design oval wire valve spring will fit factory retainer •Design delivers superior dampening
•Oval wire design allows higher valve lift & increased seat & nose pressures
•Ideal for hydraulic roller cam applications
Stock# INSTALLED PRESSURE OPEN PRESSURE COIL BIND MAX LIFT RETAINER Price Quantity
PBM3250
specs>> 110# @1.750"
Last edited by donnie_19; Jun 17, 2013 at 08:12 PM.