Can someone tell me how to install the harmonic balancer on a chevy inline six 250 with a crankshaft that doesn't have any threads in the center hole? I rented an install kit from a parts store but it was designed for the threaded center hole.

You can drill the crank for any SB bolt.

Dear Royal;

Larry's correct. Be sure it's
SAE (fine) threads.

Good luck.

It is not the best thing to do, but it is old school. A block of wood and a big hammer. It helps to heat the balancer and shoot the end of the crank with a freeze-it spray just before install.

Using a air chisel with a blunt tip on a plate bolted on the balancer to drive it on.
Any of the blunt force methods can be hard on the thrust bearing. Tom

Dear Tom;

Yes that's true.

However; the Dampner is 3/4 of the
way on, (over the key) when the
force is needed.

It's only a "couple of licks" to
set it on there etc. I usually use my
"old school block" as posted.

WD-40 helps as well.

I did use the block and the hammer but I can only get it so far in. I'm affraid to hit it any harder.

Try putting the hub on a hotplate/stove for a couple minutes and slip it on using oven mitts and tap it home with a mallet. Drilling, tapping, and beating can all be avoided and IMO if it was designed to be drawn on Chevrolet engineers would have put a thread there in the first place. Freeze/cold spray works wonders preparing sleeves/bushings for interference fits but will not reduce the diameter of a solid crank any more than a couple tenths and not worth bothering.

I will try that, thank you.

Get the damper pretty hot, up to 200 or 250 won't hurt it. Set the engine outside for a hour two will help also if its cold out. Get everything ready and shove it on in one quick step and have the hammer and wood ready. Once it stops, even for a second, its sticks. You should be able to get 3/4 or more of the way on if you are quick.

Joe

Well, I got it in today just doing it with the hammer and wood and after a long hour the damn thing is in. It's not all the way flush with the harmonic balancer but my belt does match up with the alternator. Should it be flush? I probably have a couple of cms left.

Dear Royal;

??what?? "isn't fush" etc.

If you can see the 'shiny' part
(where the seal rides) It's not
on 'all the way' yet.

I've used the moveable (tubelar)
part of an axle stand as a tool
to instal these. It makes a
different sound, when it hits the
crank gear. It's "solid" at that
point.

Good luck.

And it certainly should not have taken a "long hour" to accomplish that! I'm thinking the key was the wrong size or too high in its slot. Just a guess though.

While I am not in favor of hammering these things on (drilling and tapping for a bolt is way better) I do understand necessity. I recently pulled a 250 damper and the grease mark shows is was not flush. The end of the crank was recessed about 1/2 inch from the very outside of the dampeners face.

As my balancer warms up for the install, I did some searching and now I have a question or two.

If I tap the Crankshaft, what bolt size and thread count should I shoot for? I have not owned a V anything in years, so I have no idea the bolt size of a SBC. I also want to make sure I have the tap.

And what size drill bit for the hole that will be tapped?

Thanks for the info.

BBC size damper bolt.

MBHD

Use a 25/64 drill bit and a 7/16 x 20 tap!

The GMC uses a 5/8"-18 and we use the same dampners. A BBC should do it; make sure it is true...Good Luck

Thanks for the reply on the tap and drill bit sizes.