[my72lemans]

Originally Posted by rohrt

Has me wondering a few of things.

I have only had rods come flying out when at high RPM and usually accompanied with rod knock. What Tom V has posted about a given life cycle scares the hell out of me. I still have a 455 that I built back in the 90s and recently put the stump puller in. At the time it had ARP rods put in and were shot peened. It was the best most of us could do at the time. Its hit 6K RPM before but mostly kept under 5200.

Can a person just swap the rods without a re-balance. $250 is one thing but removing the whole bottom end is another.

The other thing I was wondering, after watching a few videos on 'at home piston and rod swaps' I see they would heat up the small end to 400 deg and just slid the piston pin in. How perfectly should the rod be centered in the piston?

I say, cannot swap without a rebalance unless they are stock rods and still wouldn't
need to pull the motor for a complete rod change
they should be centered on the money, there must be a jig for this.
what i do not understand is if anyone would do a rebuild why sink money into old stock rods when u can buy new? if u want better buy high end if u can't buy the near stock ones.

[geeteeohguy]

Steve, I did say in the first post that the car was raced a lot and that the valves were floated. The rod in question broke in the beam, about 2" from the wristpin. It stayed attached to the crank and did it's thing to the rest of the engine. I too have blown up engines, and have always had a warning beforehand. This was a really strange one.

[hurryinhoosier62]

Originally Posted by rohrt

Has me wondering a few of things.

I have only had rods come flying out when at high RPM and usually accompanied with rod knock. What Tom V has posted about a given life cycle scares the hell out of me. I still have a 455 that I built back in the 90s and recently put the stump puller in. At the time it had ARP rods put in and were shot peened. It was the best most of us could do at the time. Its hit 6K RPM before but mostly kept under 5200.

Can a person just swap the rods without a re-balance. $250 is one thing but removing the whole bottom end is another.

The other thing I was wondering, after watching a few videos on 'at home piston and rod swaps' I see they would heat up the small end to 400 deg and just slid the piston pin in. How perfectly should the rod be centered in the piston?

roht,

The ONLY way you could replace the rods without re-balancing the engine is to have the new rods weigh EXACTLY the same as your old rods. You used ARP bolts in your build. So did I back in 1988. My 400 saw MANY 6,000 rpm blasts with ZERO connecting rod problems. I still have those rods. If you choose to replace your rods, you're going to have the engine down anyway. It would be best to have the whole reciprocal mass re-balanced at that time. As far as home videos of guy pressing on their piston at home WITHOUT the jig to properly center the piston pin, all I have to say is we used to see a LOT of those people with broken engines saying "I don't understand. It just broke".

[PONTIAC DUDE]

From the factory the rods can be so far off plus and minus that I don't know how one would get a number to use as a balance point. Same deal with holes drilled in a crank to balance from the factory. I have seen upwards of 7 grams difference in rods.

Yes heating up the small end of the rod is the only proper way to install them. Centering doesn't have to be perfect but real close what you strive for. Most shops should have the proper pin tooling that limits the distance the pin goes in so all is within spec.

[rohrt]

Did the factory balance the motors before assembly?

[hurryinhoosier62]

I've never seen on that was.