Centering crank pully on damper

[JMD]

I have a generation IV 454 in my '68 K10. I installed a new damper and reused the original crank pully before the engine was installed in the truck. The damper didn't wobble at all when the engine was running, but the pully did. Not a terrible amount, but enough to make the belts dance all over the place above 2500 rpms. After about 1000 miles one of the pully bolts sheared off, damaging both the pully and the damper.

I installed another new damper as well as an aftermarket crank pully. Once again the damper is perfectly centered, but the pully is slightly off. Only by 1/16" or so, but it's very noticeable at higher rpms. What am I missing here? How do I get the crank pully perfectly centered?

[Mike C]

It should be "hub-centric". There is a raised lip in the stamping that should center on the balancer. Then you put bolts in and tighten not really any way to screw that up unless components are wrong.

[BossHogg69]

The last pulley I installed on a big block was a March Performance pulley onto a Romac balancer. The fit was extremely tight - I tapped the pulley onto the balancer with a dead blow hammer to seat it evenly then tightened the bolts down. I had a similar experience with an ATI balancer and factory BB serpentine crank pulley, the pulley fitting very tight on the balancer. Did you pull the crank pulley into the dampner with the bolts and possibly cock it sideways a bit? I guess it's possible you got two bad pulleys or maybe a bad dampner, but unlikely, imho.

[JMD]

The pulley certainly isn't a tight fit onto the balancer. With the bolts loose and the lip still engaged into the balancer I can move the pulley side to side 1/16" to 1/8". Seems like that is where the problem lies, either the pulley is too small or the balancer is too large. It is a cheap balancer, so my money is on it being out of spec. Any ideas on where to go from here? I'd rather not buy another balancer...

[randy500]

Sounds like smalll block lower pulley, they will bolt on but the center hole that centers the pulley to the balancer is smaller on the small block pulley

[randy500]

I also think you can use the small block center bolt and washer but when you do this it depresses the center of the small block pulley into the balancer recess of the big block balancer, that could be an issue too

[JMD]

It's not a small block pulley, the hole in the middle is way too big to fit on a small block. I'll find a caliper and measure the damper and pulley to see how far they're off.

[JMD]

Here's a pic of the original pulley. The new one I bought is identical to this (just not broken), and the damper is Dorman part number 594-010 https://m.summitracing.com/parts/rnb...SABEgJwyfD_BwE

The pulley simply does not fit "snug" onto the damper like it probably should. Any suggestions on how to remedy this other than buying a different, higher quality damper?