Are they a quality part? I recently installed a Dorman HB (harmonic balancer) on my 351W, 1990 F-250. It was one of those parts that needed to be replaced, the old one (not Dorman) had missing, and dry rot rubber between the inner and outer. So I decided to replace it. Right off the bat I was disappointed with the parts quality. The timing marks were extremely difficult to read, the markings were not scored deeply and the manufacturing paint was over applied. I used a wire brush to remove the paint and see the markings, which were still hard to see, but I finally made out the markings, found 10BTDC and marked it. This was a few months ago

Just recently I was checking my timing, instead of using a timing light I just pulled the cap off the distributor and turned the crank bolt by hand to the timing timing mark I made at 10BTDC. The rotor should be pointed towards the number 1 ignition post on the cap. Mine was pointed towards number 8, much closer to 8 than to 1. Truck ran fine though... (firing order for 351's is 13726548) So 8 is fired just before 1 is fired. When I turn the crank by hand to line up the rotor with the no. 1 post on the cap, the HB is reading just before TDC. So If I wanted to set my base timing, I would not be able to reliably use my HB as a reference for my base timing. I suspect the HB has moved somewhere between 1/2-1inch. There is another guy who posted on this forum who said he was running a Dorman HB and it only lasted 1200 miles before he noticed it slipped. I have only ran about 600 miles with mine and I suspect it has slipped. My timing chain is brand new and my distributor is brand new, in fact I'm running a reman engine with less than 1000 miles on it so I don't think any of those parts have jumped, or skipped.

Has anyone else experienced quality issues with the Dorman HB? If so what's your story? What HB would you recommend instead of Dorman?
-Thanks

 

Historically, I've avoided dorman parts. They're the equivalent to harbor freight tools; they work in the mean time, but they don't last long.
I don't have any experience with their harmonic balancers.

 

Bought one for my 302 that could fully seat by hand...junk in my eyes.

If you still have the original, call Damper Doctors to repair. If not, perhaps Summit/Jegs has a Daaco or Powerbond.