Flex plates
Would the damper cause that so quickly ?
I’m not questioning your opinion,,,just curious.
I was thinking maybe wrong crank balance ?
Or something out of kilter ?
What about the balance for the stroker crank,,,,could it be wrong bobweight,,,and imbalance being masked by all the other things combined.
You know,,,noise and vibration from running down the track ?
Or,,,possibly a crank flange that is not true ?
I’m assuming that this was a complete fresh engine,,,,and the converter and transmission were used ?
Tommy
It’s usually the opposite.
A piss poor balance job will show up quickly.
A bad damper (not counting the crank breaking aluminum hubs like Moroso dumped on the market back in the day because they broke parts very quickly) can take some time to do damage.
Not knowing what balancer the OP has, chances are it’s an elastomer damper.
They degrade every time you start the engine. The rubber gets heat cycles, and with each cycle its ability to dampen the torsional cycles of the crank degrades.
That’s one reason why I don’t use any of them.
I use Fluidamper on as many as I can. As a second option would be Innovators West and tied with that, and probably better than both of those and certainly better than an elastomer damper would be the TCI Rattler.
I’ve used several over the years on customers stuff but the number one gripe about them is at very low engine speed, like shutting the engine off they make a rattling sound.
All the rail birds and looky Lou’s run off at the mouth about how the engine is coming apart and the damper is killing the engine when the opposite is true.
If I had several dampers here I’d dyno test them, but I suspect with a water brake dyno you’d learn anything.
An inertia crank dyno (not a wheel dyno) would show accurate results.
I think some would be surprised at the results. In a very narrow range some elastomer dampers MAY show less harmonics but over the entire ROM range I think the elastomer dampers would be very disappointing.
In the last Small Block Engine manual Chrysler produced they cover a bit of this about their testing.
It’s worth reading if you have the book.
Edit: I went back and looked. The OP used it for a season or so.
Depending on his damper that’s a time frame where a bad damper shows up.
Since I’m a gutless turd and I hate carnage if the OP was my customer I’d want him to bring the engine back in so I could mag the crank at least.
I’d be scared to death that even if he gets a new damper on it he hasn’t already has some fractures started on the crank.
And the block. I’ve seen aftermarket blocks as tough as the BBC literally and by that I mean actually pull the mains right out of the block.
One BBC had less than 80 runs on it. It had the Moroso crank braking aluminum hub on it.
It was dropped off after I went home for the day, but the next morning I walked in, saw it on the stand and I said out loud “this is garbage”.
It broke the block, pulling the center three mains out, it had cracked the 1 and 5 mains. It had a Kieth Black billet crank and it broke it too.
It wasn’t in pieces but it had fracture in every main fillet and most of the rod throw fillets.
I knew it not because I’m smart, I knew because I’d seen it before.
What the OP posted is a bad damper. The flex plate is the canary in the coal mine.
Let’s hope he doesn’t have anything else broken.