Question: Head bolts/studs
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Postmaster
Joined: Dec 2011
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Question: Head bolts/studs
I've been doing some reading(here and elsewhere) about upgrading to head studs, because we get better clamping/breaking strength etc. However, these are expensive.
I saw one account of someone just using standard grade-8 half-inch bolts, and it worked(at least for a while), which got me to thinking:
Why not do to the 7.3 what Ford did to the 6.9, and upsize the head bolts? Is there any reason one couldn't drill and tap for 5/8" bolts, and then just use (relatively) standard ones? Sure, the per-square-inch breaking strength may be lower than the super quality "proper" ones, but the extra area should make up for it, right?
It looks like the minor diameter of a 5/8 thread(any of em) is slightly bigger than the major of a 1/2" one, so it's possible that way, but...
Does this seem possible, or am I crazy? Are the bolts too close to important things already?
I saw one account of someone just using standard grade-8 half-inch bolts, and it worked(at least for a while), which got me to thinking:
Why not do to the 7.3 what Ford did to the 6.9, and upsize the head bolts? Is there any reason one couldn't drill and tap for 5/8" bolts, and then just use (relatively) standard ones? Sure, the per-square-inch breaking strength may be lower than the super quality "proper" ones, but the extra area should make up for it, right?
It looks like the minor diameter of a 5/8 thread(any of em) is slightly bigger than the major of a 1/2" one, so it's possible that way, but...
Does this seem possible, or am I crazy? Are the bolts too close to important things already?
Lead Driver
Joined: Apr 2008
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Not enough thickness, block deflection would be crazy. Its being looked at using a 9/16 stud for a 6.9. Cant use half as it wont clean the hole good enough for good threads.
Honestly i dont think studs are that spendy. Last i heard it was $225 for replacement headbolts (should only use once) and studs are $390 and theyre re-usable.
Honestly i dont think studs are that spendy. Last i heard it was $225 for replacement headbolts (should only use once) and studs are $390 and theyre re-usable.
Postmaster
Joined: Feb 2011
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in january, i bought ARP studs for my 6.9 for right around 300 bucks from summit racing. i would do it again if i had a need. surely that costs less than having a machine shop do all the related work in allowing bigger bolts to be used, even if there weren't issues with the nearness of the water jackets and other concerns.
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Postmaster
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Do note that I'm a machinist, with (effectively free) access to plenty of equipment, even a good-sized CNC mill(easily big enough to fit and work on the block), so drilling and tapping *cost* I'm not worried about. I'm worried about breakthrough etc.
@hairyboxnoogle: You say block deflection would be bad. What exactly is deflecting, here?
@hairyboxnoogle: You say block deflection would be bad. What exactly is deflecting, here?
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RawPower
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
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May 11, 2005 08:14 PM
