MBC Racing

iTrader: (3)

my 383 blew up last friday. Was out playing around and after I yanked 2nd I head lots of banging, car died, pulled over on the side of the road and heard liquid pouring out.

I got the motor all appart today. It turns out it snapped a rod bolt right where the threded portion meets the shank. The motor has been in the car for 3 full seasons of road racing and autocross and never missed a beat.

I am glad it did it on the street since is sprayed coolant and oil all over the tire, wheel and brakes.

The motor was callies crank, rods and diamond pistons with 236/236/550/111 cam. rod bolts were ARP 2000. The bearing surfaces look good, no blueing or scuffing. Rod is intact except for being all bent.... shank didn't brake.

What would have caused the rod bolt to brake???? I would have never thought that an ARP rod bot would have broke..... Anybody else have this happen? thoughts???

Thanks

mvvette97

iTrader: (18)

what kind of Rs were you turning when it blew?

redtail2426

iTrader: (10)

sounds like a bad bolt.next time use katechs,there stronger then both series of arps.

MBC Racing

iTrader: (3)

It has seen 6900 rpm quite a few times over the last 3 years.
Yes, I know it is falling off on power up there, but it is quicker around the track to hold 3rd a couple seconds longer comming into the corner, than up shift and downshift. I have tried both ways and it definitely dropped some time by holding it. From what i understood, that was an acceptable rpm. Not like I was spinning 8k or something. It let loose on a 6600 1-2 shift with the tires spinning. Same thing as comming into a corner at 6900 lifting and braking.

Guess I will be using some better rod bolts. I still would have thought that the arp ones would have worked fine

PREDATOR-Z

I cannot speculate as to why it broke, but 3 seasons is a healthy cycle.

If you can, I would co-ordinate with ARP and send them the bolt to find out if it could be just a bad bolt. All parts break, that doesn't mean they are no good.

Shawn @ VA Speed

iTrader: (3)

I have seen this happen from moisture.The arp 2000 bolt are susceptible to moisture damage-actually eats into the material on a microscopic level weakening the bolt.Was the car sitting for a long time in a damp area without being run?

Shawn @ VA Speed

iTrader: (3)

Katech makes rod bolts for callies rods?

383lt1impala

iTrader: (33)

U never retorqued the bolts after 3 seasons? I would do that after every few months.

Shawn @ VA Speed

iTrader: (3)

retorque the rod bolts?you don't retorque rod bolts.You really shouldnt torque the rod bolts to start with,you stretch to bolt to the proper length and let them alone.Torque is a measurment of work to overcome friction not stretch.

elias_799

iTrader: (8)

i think 3 seasons out of that motor is pretty good.

BigRich954RR

iTrader: (1)

Im building my motor its sitting on a stand. Im using alot of Arp bolts Its not damp in the room but is there any thing i should do to be safe. Do i have to wear gloves while working with arp bolts ? Thought it was just the L19 bolts that had issues?

smask04C5

iTrader: (1)

If proper installation procedures are followed, stress corrosion and H2 embrittlement are typically not a problem with ARP 2000 bolts. L19 alloys are sensitive to both, and must be kept well oiled. Aermet 100 is also sensitive, but may be too expensive for most. To Shawn's point, you should never torque a bolt to some spec, as you must overcome friction to get to that number. Serious engine builders will always employ the use of a 'stretch gage' to establish clamp loads.

Mike454SS

iTrader: (4)

You don't re-torque any bolts that aren't crushing a soft gasket...not just rod bolts lol...like I could see re-doing a bolt that holds say...an LT1 intake manifold down after a couple heat cycles...but rod bolts...measure stretch on assembly like you said, and then don't touch them.

99blancoSS

iTrader: (115)

It didnt break right away and lasted good amount of time at that rpm level but one reason for a rod bolt to break could be installation error.

Shawn @ VA Speed

iTrader: (3)

In Typical cases you are correct,the arp 2000's arent affected like the l19's but i have seen several times in severe cases where this has happened,ususally where a motor has been built and let sit in an enviroment where bad condensation occurs,sometimes when a car has been parked over the winter outside and not run for a long period of time.

I would rule out installation error after 3 seasons of running

MBC Racing

iTrader: (3)

car sat in the garage or trailer. It was never left outside. May have been rained on 2 times in the last 3 years.

I agree, if it was builder error, it would have let go a long time ago.
I would like to know if rod bolts are something that need/should be changed ever couple years or not. My goal is to not have a catastrophic failure. I don't mind dropping the pan every other season IF it is necessary. I just didn't think it would/shoud be. I only run 12 events a year. 6 parking lot and 6 road course. Each road event is ~50 miles total on average. Hardly like a street car that gets pounded on every weekend.

highgear

Rod bolts may last forever in a stock motor under normal conditions BUT if I was racing; I would change out Rod Bolts at the end of each racing season. (at least)

Beaflag VonRathburg

iTrader: (176)

I think it would be interesting to take it some where and have them perform a failure analysis upon the rod bolt. That would pretty much let you know if it was installed correctly or if it was a material failure.

71CamaroLS1

I also had a catastrophic engine failure due to a broken ARP bolt, after about 40 hours of hard road course track time. The car did sit in the garage through long, rainy Oregon winters for 4 years. Given the incredible carnage inside the motor - it blew at about 6800 RPM - it was hard to tell precisely what happened. The rod bolt was definitely broken, but it appeared that it may actually have broken because the opposite bolt backed off. It was installed using a calibrated torque wrench, ARP lube, and the carefully followed ARP procedure, but even after all that it still might have been under-torqued.

If you're going to use ARP bolts, I would definitely suggest using a stretch gauge for installation. Stock-style torque-to-yield bolts are actually more forgiving of install procedure.

Mike454SS

iTrader: (4)

I did a lot of that while getting my degree...the TINY defect I found in a callies crankshaft got someone a lot of money to rebuild a very very expensive engine in a 7 second car...it's amazing what can be found...but it's not always worth bothering if the engine isn't big money.