Just got back from the machine shop.
Yes, the media used was quite harsh, so as to act quickly (time is money)
I've had it (the pullout problem) proven to me, as I was a "doubting Thomas"
We took some small block head bolts, an old block, and two old heads.
We cleaned 5 bolts with the harsh media (looked like well-used black beauty) for approximately three hours. The bolts came out mostly shiny, with some spots of black coating, and the grooves of the threads were still black. The tops of the threads looked OK to the naked eye.
Next we cleaned another 5 for about an hour. For all intents and purposes, they came out exactly like the first batch, maybe a tiny bit more black oxide was on them. I marked them with a red marker on the head, so I could tell them apart.
Then I cleaned another 10 by hand on a wire wheel. They came out as you would expect.
We then placed the heads on the block and inserted the bolts in a random fashion and proceeded to torque them to 100 Ft lbs.
All of the wire wheeled bolts held, but one stripped at 106lbs.
Two of the one hour 5 were stripped at 87 and 92 ft lbs.
Four of the 3 hour 5 stripped at 74, 85, 87, 88 lbs.
I know it wasn't very scientific, but I did clean all of the threads in the block also. An I oiled the bolt threads with clean motor oil from the same can.
I hope this may shed some light on this subject.
AC
Yes, the media used was quite harsh, so as to act quickly (time is money)
I've had it (the pullout problem) proven to me, as I was a "doubting Thomas"
We took some small block head bolts, an old block, and two old heads.
We cleaned 5 bolts with the harsh media (looked like well-used black beauty) for approximately three hours. The bolts came out mostly shiny, with some spots of black coating, and the grooves of the threads were still black. The tops of the threads looked OK to the naked eye.
Next we cleaned another 5 for about an hour. For all intents and purposes, they came out exactly like the first batch, maybe a tiny bit more black oxide was on them. I marked them with a red marker on the head, so I could tell them apart.
Then I cleaned another 10 by hand on a wire wheel. They came out as you would expect.
We then placed the heads on the block and inserted the bolts in a random fashion and proceeded to torque them to 100 Ft lbs.
All of the wire wheeled bolts held, but one stripped at 106lbs.
Two of the one hour 5 were stripped at 87 and 92 ft lbs.
Four of the 3 hour 5 stripped at 74, 85, 87, 88 lbs.
I know it wasn't very scientific, but I did clean all of the threads in the block also. An I oiled the bolt threads with clean motor oil from the same can.
I hope this may shed some light on this subject.
AC