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so Im new to ls stuff and I need some help I bought this gen III 5.3 with 862 heads and one of the valve cover bolt thread post broke off which I either didnt catch when buying it or I was stupid enough to over torque it but I just wanna know If theres another way to fasten it down or a way to repair the post
I would drill and tap. I could be a bit tricky only because if you don't center punch the bolt dead center your drill bit will want to walk of center. Use a super sharp center punch to start. Then a small diameter drill bit to start. Make sure it's super sharp. Then drill for the correct tap size.
Having said the above do you have enough room to weld a nut onto the bolt in the head? I haven't done it but have seen it done on the TV car shows to remove broken studs.
Either way I would remove the two rockers on either side to give you more working room.
If you drill and tap, be mighty careful how deep you drill!! Could maybe hit a water jacket. I agree with Che70velle that a good aluminum welder could repair this, and that's the way I'd go. Also consider that it is similar to the GM "cracked cap" technology they use on the rods, in that the two pieces should fit togeter nearly perfectly, so location, angle, etc., should be right on. It may not hurt to run the bolt into the broken piece as pictured, manipulate the screw into the head, then screw the piece down the bolt until it fits as perfectly as possible on the head. May have to rotate the bolt slightly up or down, too, until the piece nests as good as possible. Maybe leave the bolt in as the aluminum is welded to ensure no movement of the boss.....
Are they the early style heads with the notch on The deck surface..i have a set of those castings sitting out in the garage id be happy to send to you , providing you covering the shipping!!.they came off of a 2000 LM7 they are bare castings though
Are they the early style heads with the notch on The deck surface..i have a set of those castings sitting out in the garage id be happy to send to you , providing you covering the shipping!!.they came off of a 2000 LM7 they are bare castings though
My only problem with drilling and tapping is that the thread post isnt long enough to drill and tap because Id be drilling straight down into the intake runner and at some far point in the future I do wanna run boost and Id be worried about it cracking
Ive had the engine apart for some time and the heads are off the reason I wanted to repair it is because they guy I bought it off of said that they were upgraded valves and .660 springs and I dont wanna spend the money on new castings then have to pay to get them all matched
If you decide to drill and tap you should be able to tell when you drill thru the bolt so you don't drill into the head. You would only need the bolt diameter worth of threads in the boss. Those valve cover bolts don't need to be really tight. The other three valve cover bolts will locate the valve cover just fine.
One more thought. Can you get a really small center punch/chisel and try tapping on what's left of the bolt on the edge and rotate the broken part out?
If you decide to drill and tap you should be able to tell when you drill thru the bolt so you don't drill into the head. You would only need the bolt diameter worth of threads in the boss. Those valve cover bolts don't need to be really tight. The other three valve cover bolts will locate the valve cover just fine.
One more thought. Can you get a really small center punch/chisel and try tapping on what's left of the bolt on the edge and rotate the broken part out?
The bolt is not sheared off into the head it's the boss that snapped off.
If it were one of the center two bolts, I’d say it would be fine, but it’s an end, and it’s gonna need a fastener out there to keep oil weeping away. At least that’s my take on it anyway.
If it were one of the center two bolts, Id say it would be fine, but its an end, and its gonna need a fastener out there to keep oil weeping away. At least thats my take on it anyway.
You're likely right, but these cast valve covers are pretty rigid, not like the old stamped SBC valve covers. It still might work.
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Help broken threads on 862 heads 
