427 stroker balancing

[951mat]

I broke a valve spring at run-n-gun and decided to pull the motor to freshen it up, especially since I didn't know what kind of internals it has. Good thing I did, because we found at least one spun rod bearing and a broken cross main bolt. My engine guy says its a 428 crank b/c of the large counter wieghts. I know a 428 is balanced externally, but my alum flywheel looks like a 427 and the front sleeve on the crank doesn't have that counter weight on it either. The flywheel does have some holes drilled on the edges though. Could this enging be properly balanced like this?

Mat

[blykins]

If the crank is internally balanced, yes.

If the crank is zero balanced and the balancer/flywheel are zero balanced, then it could be balanced.

[Jerry Clayton]

Are all the drilled holes in the flywheel together in the same area? maybe 6-8 3/4 in holes?

[951mat]

Not exactly. There's 3 together one by itself and a couple of shallow drilled holes. See my gallery for a picture. Thanks for any help. I'll be curious as to what my builder says.

Mat

[Anthony]

Originally Posted by 951mat

Could this enging be properly balanced like this?

freshen the crank, and run it on a balancer with your parts. That'll tell you. If its not balanced, then you either need to get the right flywheel, or internally balance the crank.

[RICK LAKE]

951mat Looking at the flywheel it was possibly 0 balanced. Crank looks the same way. With the damage to the crank, you should have the motor gone through completely and rebuilt. The crank may need just a polish of the journal and would replace that rod. This would be the cheap way with polish and rod. The better way is have the crank done, all the rods checked, balance the bottom end with flywheel and balancer all as one unit. Have the heads both checked out. Any idea why the spring broke? bang the motor off a limiter? spun bearing is a possible oiling problem or clearance got to large for that rod bearing or the bolts stretched. Are there ARP bolts on the rods? Doing a short block rebuild may be cheaper in the long run. If you are going to keep racing, have the motor oiling system blueprinted, and add a Melling HVHP pump with harden shaft. Rick L.

[Buzzmobile]

mat, who are you going to have build it? stanley?

[951mat]

yea Buzz, its at his shop now. I need to take him the flywheel today and the 3 pistons I pulled. I can't wait to hear what he finds, although I'm preparing for the worst. The kids need a skinny x-mas, they have too many toys already.


Mat

[CJ428CJ]

If its 428 crank and it's been balanced internally, you should be able to see slugs of heavy metal in the crank counter weights. I think they drill a hole in the counter weight, add a slug of heavy metal and then weld it back up. My crank was externally balanced and it was pretty easy to see where they added the weight.

Chris