magnum head bolts, reuseable? torque to yield type?

heads are off again for the coolant leak from Hell & are these bolts (MP) reuseable? they "look" OK but it is a racing app so I gotta confirm. thank you for your time.

Stock magnum 5.2/5.9 headbolts are not TTY and they can be reused. I've done it several times without issue

I've got a brand new set in a box if you're interested. R/T springs too.

these are what I have.

They're just regular bolts. Think of the torqueing directions...If it doesn't say torque to x lb ft and then y degrees after you hit the torque values, they are not torque to yield.

AND, although there is a lot of hysteria on this board about TTY bolts, the TTY bolts could probably be reused. You'd have to take a Materials Science course at Big Red to have it explained properly. But basically whatever stress is developed in the yielding would be the new elastic limit for the bolt, until you got noticeable necking down. As I have said many times, my Mercedes engine has TTY rod bolts and the FSM says they can be reused until the necked down portion reaches a minimum diameter. Of course, that was 40 years ago, but steel hasn't changed that much in that time.

What I'd be looking for in any torqueing situation is when you reach the torque value and the head keeps turning with no increase in the amount of pull you are putting on the torque wrench. This is for a non-TTY bolt. Most bolted joints are torqued to between 75 - 85% of yield. What I described above is yield, and if the bolt yields when it isn't supposed to there is a problem with the strength of the bolt either material or heat treat and it needs to be replaced.

And, if the FSM says replace the bolts do it. A set of bolts costs in the same range as a tank of gas. The designers know more than I do about that particular application.

R.

Dog you're the man!

Back when I was changing Neon head gaskets the rule of thumb for reusing TTY head bolts was to lay a straightedge on the threads, if they all touched it was good to go, if not put in new ones.

But again, magnum bolts are not TTY. All good points about TTY bolts, but for a magnum head on a magnum block, stock magnum head bolts can be reused.

that's what I wanted (needed) to hear. I will reuse em & move on to other issues. thanks guys.

use a stretch gauge..get them from arp

Hmm. How do you check a head bolt for stretch?