[mgarblik]

Originally Posted by Jay S

Most the factory Pontiac cranks I have seen broke in the same place like in Paul’s FB video. Thru the throw just inside the RJ. If it was something with the dampener it seems to break on the front throw right behind the number 1 main.

It seems like takes a smaller RJ diameter to get a very good fillet there that adds much strength there. I think it would have still broke.


It seems like it is fatigue life that breaks them with a mix of street driving and racing more often than big HP racing. It is hard to catch them before they fail because they do not start small cracks that you can inspect or mag, they hit the fatigue limit and just completely let go. About all the examples I can think of that broke cranks were for street duty. Lee has broke a 400. Jim Hand lost one his first 455. Mchell broke one in his 455 not that long ago. I can think of a few that broke that had some welding done. Steve C. had one the broke. You don’t have to look very far, they are all on this board. Another member broke one like the one your working on Paul, but the crank snout and dampener ended up in a road ditch, along with the front block webbing.

These are all good points to consider. A street or street/strip crank isn't going to be removed and inspected on a regular basis like a race crank. A cast crank would be more likely to suffer a catastrophic failure than a forged one due to material and production process. Chinese forged cranks were not available when we were racing high HP Pontiacs. It was stock cast or billet only. Building a HP engine today, I would use a properly inspected and prepared forged crankshaft.