440 Source Balance Job

Save your money and have a local shop balance it. New balancer or not, I've seen way too many cranks not c lose to what I call balanced.

The only way to know if they got it right is to pay someone to hang the bob weights and spin it up. It seems everyone claiming their crank was balanced correctly never checked it.

You can just have 440 Source do it and run it. It won't shake. But neither did the OE Chrysler balance, and I don't know anyone who calls that a balanced crank.

One quick example of how far out they can be and not shake.

We had a customers Super Gas roadster on the chassis dyno. It was down on power (he got whiskey throttle in the burnout and bent a bunch of valves and then he jacked up the tune up and knocked the moly out of the rings) but it was smooth. I drove it on the dyno several pulls and it didn't feel like anything but normal.

The engine comes out and we start the process. We didn't build the engine and if I didn't do something it gets done again to verify its correct.

The first thing I came across was the damper end of the crank was externally balanced and the flywheel end was internal. Very unusual but I'd seen a couple of instances where that's what it took.

I start to spin the crank and the crank damn near jumped out of the balancer. I then verified the bob weight card by weighing everything again and doing the math. It was dead on. So I sneak up on the crank speed and at 250 rpm I can get a reading. It's not smooth, not even close but I could see what was going on.

The damper end was 5 grams out and the flywheel end was 85 grams out. That's a WTF is this crap moment. I call the boss over and show him what I had. He said call the customer and get him down here to explain this.

He comes down and I show him. He says I'll be back in an hour. When he gets back he had a taco'd flywheel. It was folded up.

Then he says "I was unloading at the track and I didn't get the ramps right. I caught the flywheel on the lip of the door and it folded up. So I bought this one (the one on the crank at the moment) and I've run it for awhile now".

He had installed an internal balance flywheel on a crank that needed an external balance flywheel. And it didn't shake.

When I got the correct flywheel it was on about 25 grams off, as the last shop made some corrections on the flywheel. It was 5 grams out on both ends when I got it done.

Moral of the story: Just because it ain't shaking doesn't mean its balanced. This of course wasn't the fault of the last guy who touched it. Clearly the car owner was over his skis on things like this. 100% on the owner.

But, had I not checked the balanced job, it would have went back in the car with the wrong flywheel on it and eventually there would have been a failure. Check the balance job or hope its close.