Question: Head bolts/studs
Thread Starter
|
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
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
Posts: 6,945
Likes: 13
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
Posts: 3,560
Likes: 1
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.
Thread Starter
|
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
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?
Thread
Thread Starter
Forum
Replies
Last Post
RawPower
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
2
May 11, 2005 08:14 PM
