Cracked heads
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Cracked heads
Took in my 6.9L heads to have re-surfaced. Intending on installing first gen banks turbo with ARP head studs. Anyways, after I got them back from the machine shop I found these cracks on every fuel port on both heads. I called to ask the machine shop about it and they explained this is normal and won't hurt anything. Opinions? Ok to use or seek a second opinion and possible repair?
My concern is that thru normal operation this thin area may become fatigued and break off in the cylinder eventually.
Note:
These cracks are probably not caused from the recent machining but due to the casting process itself? I think from the cooling rate between the thick and thin sections. It's just how it looks, not really machining tears.
Thanks
My concern is that thru normal operation this thin area may become fatigued and break off in the cylinder eventually.
Note:
These cracks are probably not caused from the recent machining but due to the casting process itself? I think from the cooling rate between the thick and thin sections. It's just how it looks, not really machining tears.
Thanks
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New User
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They didn't say but it wasn't much because the other head shows signs that it didn't clean up all the way. I put a straight edge on it and couldn't get .002 feeler thru it.
Methanoholic
Joined: Mar 2009
Posts: 6,442
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From: Maine (NorCal Native)
Just so you know, it is important to know that sort of information in a zero clearance motor!
Regardless you need to check/verify your clearances anyways so it's NOT required info.
Technically, they should be done the same so they are all equally CC chambered ... Does it really matter, no, unless you are going for a precision build!
-Enjoy
fh : )_~
Regardless you need to check/verify your clearances anyways so it's NOT required info.
Technically, they should be done the same so they are all equally CC chambered ... Does it really matter, no, unless you are going for a precision build!
-Enjoy
fh : )_~
Postmaster
Joined: Dec 2011
Posts: 3,860
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What you need to be aware of is the valve recession clearance:
Intake: .041-.054
Exhaust: .051-.063
http://robbiethe1st.afraid.org/image...Head_specs.jpg
This is the measurement from the valve head to the (now decked) head surface. If you have too little clearance there, the valves and/or seats will need to be machined. Otherwise... you'll have problems.
Intake: .041-.054
Exhaust: .051-.063
http://robbiethe1st.afraid.org/image...Head_specs.jpg
This is the measurement from the valve head to the (now decked) head surface. If you have too little clearance there, the valves and/or seats will need to be machined. Otherwise... you'll have problems.
Cargo Master
Joined: May 2001
Posts: 3,208
Likes: 13
You also need the check how far the Pistons are above the block deck. Stock is .010 you are allowed .036. Most of these blocks need to be decked due to fire ring galling. Not doing it invites head gasket failure. If you exceed the .036 number Pistons can be purchased that are.010 or .020 shorter then stock. Valve recession can be fixed by grinding the seat a little deeper. Then grind the stem to correct length.
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fordtrucksforever
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Feb 23, 2003 11:10 AM
