Cracked valves guides tip, can I rebuild head like this? (Pictures)
05-30-2015, 01:53 PM
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Cracked valves guides tip, can I rebuild head like this? (Pictures)
Hello!
I removed the valve springs from my sbc double humps heads yesterday and wanted to swap out to new springs to match my new roller camshaft.
After inspection, I realized that most of the valve guide tips (I think they are called valve guide bosses) are cracked. It's weird, the cracks seem to be only on the outside layer of the guide. I can't see the crack going completly trough the guide neither I can see a crack from inside any of the cracked guides.
I wanted to know if that was a common issue, if that could be used for a street driven engine.
Otherwise, what are my options? Can this be re-worked? (seems that the guided on this engine are not changeable.
Can they be welded and machined? Can they drill out the guides and install new ones?
I guess I'll have to go to a machine shop but I always prefer getting your opinions before because I can't imagine a machine shop saying I can use those heads like that when they'll see the opportunity to make some cash (againnn) out of me...
thanks a lot and here are the pictures
https://www.dropbox.com/sc/j4hgcbzeh...ecD61HaQ_zmmIa
I removed the valve springs from my sbc double humps heads yesterday and wanted to swap out to new springs to match my new roller camshaft.
After inspection, I realized that most of the valve guide tips (I think they are called valve guide bosses) are cracked. It's weird, the cracks seem to be only on the outside layer of the guide. I can't see the crack going completly trough the guide neither I can see a crack from inside any of the cracked guides.
I wanted to know if that was a common issue, if that could be used for a street driven engine.
Otherwise, what are my options? Can this be re-worked? (seems that the guided on this engine are not changeable.
Can they be welded and machined? Can they drill out the guides and install new ones?
I guess I'll have to go to a machine shop but I always prefer getting your opinions before because I can't imagine a machine shop saying I can use those heads like that when they'll see the opportunity to make some cash (againnn) out of me...
thanks a lot and here are the pictures
https://www.dropbox.com/sc/j4hgcbzeh...ecD61HaQ_zmmIa
Last edited by guillaumeber; 05-30-2015 at 01:55 PM. Reason: wrong link
05-30-2015, 02:12 PM
#2
Melting Slicks
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Hello!
I removed the valve springs from my sbc double humps heads yesterday and wanted to swap out to new springs to match my new roller camshaft.
After inspection, I realized that most of the valve guide tips (I think they are called valve guide bosses) are cracked. It's weird, the cracks seem to be only on the outside layer of the guide. I can't see the crack going completly trough the guide neither I can see a crack from inside any of the cracked guides.
I wanted to know if that was a common issue, if that could be used for a street driven engine.
Otherwise, what are my options? Can this be re-worked? (seems that the guided on this engine are not changeable.
Can they be welded and machined? Can they drill out the guides and install new ones?
I guess I'll have to go to a machine shop but I always prefer getting your opinions before because I can't imagine a machine shop saying I can use those heads like that when they'll see the opportunity to make some cash (againnn) out of me...
thanks a lot and here are the pictures
https://www.dropbox.com/sc/j4hgcbzeh...ecD61HaQ_zmmIa
I removed the valve springs from my sbc double humps heads yesterday and wanted to swap out to new springs to match my new roller camshaft.
After inspection, I realized that most of the valve guide tips (I think they are called valve guide bosses) are cracked. It's weird, the cracks seem to be only on the outside layer of the guide. I can't see the crack going completly trough the guide neither I can see a crack from inside any of the cracked guides.
I wanted to know if that was a common issue, if that could be used for a street driven engine.
Otherwise, what are my options? Can this be re-worked? (seems that the guided on this engine are not changeable.
Can they be welded and machined? Can they drill out the guides and install new ones?
I guess I'll have to go to a machine shop but I always prefer getting your opinions before because I can't imagine a machine shop saying I can use those heads like that when they'll see the opportunity to make some cash (againnn) out of me...
thanks a lot and here are the pictures
https://www.dropbox.com/sc/j4hgcbzeh...ecD61HaQ_zmmIa
The guides are not cracked. The guides have had a knurling tool run thru them which was a common practice many years ago. The knurling tool leaves a spiral groove (resembling a thread) inside the guides. It was a "quick-and-dirty" way of resizing the guide before a final reaming job.
05-31-2015, 06:57 PM
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Hello Toobroketoretire!
I'm not talking about the spiral thing in the inside diameter of the valve guide, but instead I'm refering to the cracks... literally cracks on the outside diameter of the guides.
Look carefully at the pictures, you will see what I mean!
But..thanks for taking the time!
g.b.
I'm not talking about the spiral thing in the inside diameter of the valve guide, but instead I'm refering to the cracks... literally cracks on the outside diameter of the guides.
Look carefully at the pictures, you will see what I mean!
But..thanks for taking the time!
g.b.
05-31-2015, 07:04 PM
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Melting Slicks
Member Since: Apr 2009
Location: Great Plains Iowa
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Hello Toobroketoretire!
I'm not talking about the spiral thing in the inside diameter of the valve guide, but instead I'm refering to the cracks... literally cracks on the outside diameter of the guides.
Look carefully at the pictures, you will see what I mean!
But..thanks for taking the time!
g.b.
I'm not talking about the spiral thing in the inside diameter of the valve guide, but instead I'm refering to the cracks... literally cracks on the outside diameter of the guides.
Look carefully at the pictures, you will see what I mean!
But..thanks for taking the time!
g.b.
I don't think those are really "cracks" as such but rather small stress cracking in the surface. If the cracks were deep enough to go into the water jackets there would be evidence of seeping. If in doubt have an automotive machine ship Magnaflux the heads..................
