I already have the large 27mm bolt removed from the engine.  The balancer has two threaded holes that are to be utilized when using a puller per the FSM.  Unfortunately it does not state what size the holes are.  An M6x1.0 bolt is too big and a M5x0.8 bolt is too small.  I have spent about 20 minutes trying various bolts in my collection and so far no luck.  Does anyone know what size the holes are?  Thank you.

Found this in my 1976 FSM.  Weirdly, it doesn't show L28 as an application.  But it does imply the bolts are 1/4", non-metric,  also weird.

Thank you Zed Head.  Unfortunately 1/4 inch is too big.  After some more trial and error I have determined they are SAE 12-24.  Now the hard part is finding a strong enough bolt in that size that will be long enough to work with the puller and not break.  The search continues.

I discovered the SAE thread anomaly, too.  I can't remember what I used as the puller cross-piece (maybe my generic steering wheel puller), but my recollection is that it really didn't take much force to make the harmonic balancer free up.  I'm pretty sure I just used hardware-store grade bolts.  Why not give it a try before you get too worked up about trying to find high-strength bolts?  The balancer is a tight sliding fit, but not an interference fit...

... unless there's been corrosion at work.

12-24? Seriously? That's evil. Sure it exists, but nobody ever uses that size!

Honestly, I suspect they are really M6-1.0 but there is rust in the threads that make it seem as though the M6 is too big. For the record... M6-1.0 (converted to inches) is .236 x 25.4 TPI

And (according to a quick web search) 12-24 has a major diameter of .216 in. So 12-24 would be .216 x 24. So 12-24 (converted to metric) is M5.5  x  1.06

I bet you could run a M6x1.0 tap in there and clean up the threads. Or maybe you could give a M6 x 1.0 bolt a quick hit with a file and knock the crests off the threads and it might fit?

I'm certainly not saying it's impossible, but I'm just very skeptical they did that!

Good news, I got it off.  Just as Namerow predicted, once it was started it came off with just some medium effort.  I used a pry bar to gently push on it and I could see the shininess of the crank in the gap between the balancer and the timing cover widen.  Once it was 1/3 away from the timing cover I was able to work it off by hand.

I tried a M6x1.0 bolt and tap and it would be quite a bit of material to overcome.  I was happy to get it off as everything else came apart as planned with no surprises.

Edited August 10, 20186 yr by Hardway