4.6 vibration at 2500+ RPM

[Thorwon]

I've built a 4.6L short rod stroker. I used a 1988 Comanche block, the light crankshaft and rods from a 4.2L.

SPEED PRO Hyper H802CP40 pistons.

The camshaft is a Crane Cam H-260-2, .456 intake .484 exhaust.

And a 7120 head.

I put a new Dorman 594-018 Harmonic Balancer on it.
It starts and runs great, but at about 2500 RPM there's a vibration and the higher the RPM the worse it gets.

Idling it's as smooth as it should be.
Everything I can think of is right. 
Anyone have any ideas what it could be?

[ratrapp]

did you have the rotating assembly balanced?i bought a stroker kit once that said it was balanced and ready to go.it was not and it had to come back out again and taken to a machine shop to be balanced properly.

[Thorwon]

The crankshaft was not spin balanced but all the other components were balanced. I checked every thing. 

[Eagle_SX4]

Does the vibration happen when your driving or when parked and just revving the engine?

[ghetdjc320]

How may counterweights on the crank? I’m assuming you’re positive this is an engine vibe and not a tranny, flywheel or drivetrain vibe?

[Thorwon]

Yes it makes it when parked and revving the engine. 

It's the non weighted crank. I've always just called it the light weight crank.

I am positive the vibration get bad as the RPM goes up. 

 

Question for ya'll. I'm running a AW4 behind the 4.6, can anyone tell me what the pilot hole in the rear of the crankshaft is?

I never checked to make sure the torque converter fit the crank.