Don Terrill’s Speed-Talk

Dynoed a Corvette engine everything went well, Pulled the drain plug to change the oil and there appeared to be something blocking the drain hole. Dropped the pan and found the bolt with the head missing in the pan along with the washer and head of the bolt.

ARP asked if I installed the washer correctly and I told him I would not have called if I put it on upside down LOL.

Good thing I put splayed caps on the block as it was a 2 bolt main. Bearing and crank look great.

Called ARP and told them what I had found, They said they sell 100's of thousands of bolts and this does happen once and it while. My only question was there is nothing going on is there with their product and he said.

Sure was a good time to catch it.

Makes you feel warm and fuzzy eh?

Couldn't ARP take it back and do some stress crack analysis???

Carl I've had problems with arp bolts and nuts to brittle before just threading the nuts on the threads where falling off. I haven't seen that before.

lucky it broke off where you could get it out easily

Dumb question here; Was the bolt stretched or torqued? To what value?

BlitzA64 wrote:Makes you feel warm and fuzzy eh?

Always nice when the companies answer is "eh, stuff happens...".

However, I guess that is the harsh reality with mass-produced, every-penny-counts manufacturing...

I've had grade 8 bolts break off hand threading them in or just snuggin them down. Something about that peice of metal was flawed or had a major impurity in that spot and the work done to form it enhanced that flaw, but not enuff to break until a little pressure is applied. Still I would have thought if that was the case it would have failed on the 1st step of torqueing. Only time I seen a main bolt break and fall out is when the block cracked.

stokerboats wrote:Dumb question here; Was the bolt stretched or torqued? To what value?

How would you strech a main bolt??? Since its going into a blind hole !!!!!!

Torque the bolt to the spec offered by ARP and I have used 100's of sets of Main bolt kitsand never a problem till now.

stretch is done in a blind hole by a torque to yield process using a torque spec then angle degree. doesnt apply in this case though since im sure arp doesnt have a spec for that.

Carl is it possible there was a vibration in the bottom end, I know one thing the manufacture will never admitt to something wrong with their product.

do we have to zyglo all our bolts?
was bolt too hard?
inclusions,
embitterment?
did the break look like bad cast iron?

hodge wrote:Carl is it possible there was a vibration in the bottom end, I know one thing the manufacture will never admitt to something wrong with their product.

I balanced the rotator and the main cap showed no signs of moving or fretting was very smooth on the dyno. The main bearing looked like it was never run.

CNC BLOCKS wrote:

stokerboats wrote:Dumb question here; Was the bolt stretched or torqued? To what value?

How would you strech a main bolt??? Since its going into a blind hole !!!!!!

Torque the bolt to the spec offered by ARP and I have used 100's of sets of Main bolt kitsand never a problem till now.

Ha. There I go again not thinking. For whatever reason I was thinking rod bolt. Sheesh.lmao/again

In 20 years of production machining I have seen cracks in bar stock several times. It is very probable that the material was flawed and it wasn't caught.

Brent