1988RedT2 MegaDork
7/21/23 3:19 p.m.

As is so often the case, what started out as a simple "bolt on bling" exercise runs into a snag. 

Residing in the engine bay of the '66 Chevy II is a SBC of 1990's vintage.  I don't know much about the engine, since I bought it as a fresh rebuild.  The seller was going to put it in his son's car, but son sells car, so... sell engine.  I buy engine.

The harmonic balancer on the car is 1.25" thick.  Only a little more than 1/4" is currently over the end of the crankshaft.  I suppose there might be as much as 1/4" that the balancer could go further on before it started dragging on the timing cover, but as it's been in this state for going on 18 years, I have no delusions that it's going to move.

My goal today was to install a shiny new crank pulley from Billet Specialties.  You might think their stuff is overpriced, but dang that thing looks like a mirror.  And you know how wives do like shiny things.  Being made of a nice chunk of machined aluminum, the pulley is about 5/16" thick.

The balancer bolt I have now has an underhead length of about 2.125".  Adding the thickness of the lock washer, big flat washer, and the pulley, and spanning the open space to the end of the crank, we have used up about 1-5/8", leaving a whopping 1/2" or less that will actually hold the pulley and balancer on the crank. 

So, my question:  Will a longer bolt solve my issue, or do I have other concerns here?


Edit:  Okay, having watched an install video, I see that there is a good bit of a snout on the balancer, and I'm going to assume (!) that the builder installed the balancer correctly.  I feel pretty good about a longer bolt being a sufficient solution.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
7/21/23 3:51 p.m.

The damper is a press fit, are you sure that it is installed all the way?  You need an installation tool or a series of mighty whacks with a heavy hammer.


The bolt is mostly there for looks, the press fit does all of the work.  Chevy did not even install a bolt on some engines.

1988RedT2 MegaDork
7/21/23 4:36 p.m.

I guess what I didn't understand was that the balancer includes a "snout" that engages more of the crankshaft than it at first appears.  The end of the crank is about 15/16" short of the outside of the bore of the balancer.  I am fairly comfortable at this point.  We'll see if it falls apart at the worst possible time.  cheeky

81cpcamaro SuperDork
7/21/23 4:43 p.m.

If the pulleys lined up, the balancer was on correctly.  I can see with thicker aluminum pulleys where you may need a longer bolt, so no problem going with one.  Edit: yes the crank does end up short from reaching the end of the balancer, they are all like that. The early SBCs didn't have crank bolts at all.

1988RedT2 MegaDork
7/21/23 4:47 p.m.

Yup.  With the new pulley bolted on, the alignment with the water pump pulley is perfect.  I will procure a longer bolt. 

Thanks, guys!

Edit:  It might bear mentioning that prior to today, the engine did not have a crank pulley.  I just addressed one more of the things that need to happen before this thing cranks for the first time.

Cousin_Eddie (Forum Supporter)
Cousin_Eddie (Forum Supporter) Dork
7/21/23 5:37 p.m.

It's a 7/16-20 thread bolt. Should be easy to get one at your local hardware source.

Many years ago I had a 1964 Chevy II car with a small block. I keep thinking there was something queer about the harmonic balancer situation on those cars. I want to say I had to run the smaller diameter 6 3/4" size balancer and not the normal 8 inch SBC balancer like a majority of small blocks used. I may be washed up on that though. It's been about 30 years.


Our Preferred Partners