The Stovebolt Site Forums The Shop Area Engine Shop harmonic balancer retaining bolt

Is there any benefit to drilling and tapping the crankshaft snout to accomodate a haramonic balancer retaining bolt (on my 23), as the later V8's have?
ever hear of a balancer walking off the crankshaft?

The press fit is pretty tight. As long as it lines up with the gen & water pump pullies it should never come off. I've have no trouble with my 38. Having said that, drilling & tapping the crank will make installing a new one easier. I had to use a BFH on mine.

yes, they can come off...mine did on my 52 while on the hi-way.. lucky did not hurt anything other then 70 bucks to tow it home..

I knew mine was lose because of the slack on it even when the belt was tight but I kept drivin cause I didnt think it would come off.. got me a new pully and I check to make sure the belts and pully are tight.. If I had the engine out , I would consider drilling for a bolt, other wise yours will probably last a while

Ouch Joker! That had to hurt! Glad it wasn't to serious.

Can you drill and tap that without affecting the balance of the crankshaft ? How far would you drill into the crank ? What thread size would you tap ?

I had one come off a few years ago on "CURLY 1", my 1966 C-10. I was going about 65 MPH at the time. When it came off, it hit the radiator and ruined it.

A few months earlier, I had set the timing, and the timing marks were in the wrong position. That evidently was a sign of a problem with the harmonic balancer.

I had one walk off in a 1966 c/20 327 engine.It ruined the crank and balancer,so i pulled the engine and gave it a complete rebuild.

Hy guys, to answer some questions, yes you can drill and tap it without affecting the balance, because you are removing material at the center of the mass not at the cicumference. If you tap it 7/16" N.F. you can use a small block Chev bolt and washer setup. I would drill it at least 1" deep. And lastly yes I highly recommend the procedure to prevent the balancer walking off, I do it on all my engine rebuilds, hope that helps.

Joker, I hate to say it but, I told you so. Glad nothing else was damaged.

3B hit the nail on the head.....the end of the crank is tapered so the drill bit centers itself. Most H/B-steering wheel pullers ($10.)are 9/16 fine threads, but you don't need to thread the puller into the 7/16" threads. Put a 1/2" nut up against the threads you cut and use the puller, bolted to the balancer, using the existing factory-threaded holes, to pop the balancer off.

The beauty of taping the crank, which incidently drills and taps like butter, is that it makes the INSTALLATION a snap! No BF hammer and the damage it can cause to the timing cover seal. (I leave my timing cover loose so the seal seats squarely on the H/B.) You simply use a long 7/16 fine thread bolt and the body of the "puller" as a washer and use another 7/16"-fine nut to push the balancer home. The 7/16 taped hole with bolt and large washer will insure that your balancer doesn't "walk off".

While you're at it, tap the front main cap for 3/8 threads so that you can pull the timing cover by removing ALL the bolts from the front of the engine. No need to pull the pan to get at those 2 pesky bottom timing cover bolts. This is a real time saver if you ever need to change out the cover, seal or check out the timing gears. I can now pull the radiator and R&R all the lower end stuff without pulling any sheetmetal.

Hope this helps!

cletis, that was one before the current one,, I keep a good eye on it, this one only walks a little, as long as the belt is snug, it is ok............all the way to Kansas city........