Anyone ever see this?

[racing89]

Finally got around to pulling my daily-driver stroker apart. Belive it or not , it still run (a little noisy though)Anyone ever see this?

4.6l 004.jpg

[basscat]

[SilverXJ]

How did that happen?

You should be able to JB weld it back together and be good.

[I6FAN]

Was that a new or used crank, and was it Magnafluxed before your build?

[IH 392]

You should be able to JB weld it back together and be good.

I would use super glue myself.

I've replace several Wisconsin V4-65 crank shafts that were snapped in half, never seen an AMC crank broken like that?

[racing89]

It was just left over pieces from our race program that I slapped together 5 years, 100000 kms, and many rpms ago. Was magnifluxed(I think). I hope my new 4.08 stroke crank doesnt end up like this!

[gradon]

What rpms did it get up to? Any specific sustained rpm? Which crank is it(12-weight, 4-weight long snout, or 4-weight short snout)?

[racing89]

4 weight long snout. never over 6x grand. thinking balancer issues, as I have had in the past, suspicious, abnormal wear on the snout where the balancer rides.

[Jeepsr4ever]

Looks like a typical fillet radius break. I believe those cranks have a 3/32 radius on the rod journals this makes then prone to cracks and possible breaks. Most will try to get 1/8" radius or larger. Bummer! Hopefully your rod isnt bent and you can just swap in another crank and bearings. When you have a break like this sometimes the wrist pin does a number on the piston pin bore so if your plan is to rebuild have it all looked over.

[6TIME]

Yikes! I hope my 4wt crank doesn't do that!

[racing89]

just gonna be a spare. Was sonic tested and cant go much over the .040" its punched out. Ring gap 100000 kms ago was pushing .026".Have old race engine (4.0" bore 3.902 stroke) to put in my 88 comanche daily driver for now. Cant wait ! Been driving, knocking stocker for 8 months now!

[Jeepsr4ever]

Have you been pretty happy with the power?

[racing89]

Very much so, although I didnt fully appreciate it untill I had to install a stock 4.0l

[Cheromaniac]

thinking balancer issues, as I have had in the past, suspicious, abnormal wear on the snout where the balancer rides.

Agree. The crank broke at the front so the most likely reason is indeed a balancer issue. I've seen cranks on other engines break in the same place when they've been supercharged, probably because of overtight blower belts.

[Spliffotticle]

I have blown 2 4.0l engines due to piston slap. I remember when things were made out of metal : ( Yours is new to me.