Thread: stripped crank nose

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I went to install my harmonic balancer on my small block and the damn threads are stripped about half way down.What do I do about this?If I drill and tap it out to the next bigger size then I cant use a balancer installer.If I try heli-coil it I'm afraid it will pull the coil out,plus I havent found a heli-coil that goes that deep.I seen one time in one of the hot-rod mags were they bought a kit made just for this problem but I cant rememmber who made the kit(which includes a drill and tap and heli-coil).If anyone has a solution to my problem please help me out,thanks.

Chase the threads with a bottoming tap and install a grade 8 stud with Loctite. Use a nut to retain the damper.
Use some 400 sandpaper to lightly sand the inside bore of the damper to make sure there are no burrs. Feel around inside with your fingers. Make sure the crank snout is de-burred as well. Oil both surfaces well and use a piece of pipe a little bigger than the crank snout to bang the damper on with a block of wood held between the pipe and your BFH, then secure it with the nut.

What is a bottoming tap?Would a thread chaser be better than a regular tap?
How would I install the balancer with the stud?Could I knock it on with a 2x4 for cushion?I dont want to damadge ANYTHING.Thanks for some advice.

Tech? you wanna handle this? Bottoming tap has threads all the way down the shank(or fluting) as it goes in, it does not leave material untouched and will "bottom" out in the end blank (bottom) of the hole . Use a BFH, but make sure it a lead shot mallet, no steel hammers. I can can't see the problem first hand. Follow Tech's instructions. I own the kit to solve this. It is not readily available to the public so I am gonna tell you to go old school as much as I can with you.

When a hole is drilled and tapped, the starter tap is ground away to a smaller diameter on the nose of the tap to make it easier to start in the hole. A bottoming tap is full size all the way from the nose to the shank and will tap the partial threads at the bottom of the hole. You'll need these to assure enough grip for your stud.

Hot rodders have been pounding dampers on with a BFH and block of wood ever since there have been motors to dampen. I use a heavy wall piece of pipe against the damper hub and have a friend hold a 2x4 against the pipe while I whack the wood with a BFH. Reason for using the pipe against the damper instead of the wood against the damper is that the wood will also push against the outer ring and might damage the elastomeric material between the hub and outer ring.

De-burr and oil everything like I said and go for it. You can put the damper on and then choose the stud for length.

Inside the box with the new balancer I bought there were instructions to boil the balancer in boiling water for 15 minutes and it would expand it enough to intall wiithout a tool. It said it harmed the balancer in no way.

I didn't need to do it as I used a grade 8 bolt to pull it on, but the boiling trick may help you get it seated easier. Mine was also on a sbc.

Don

Thanks Don. Good one...let's not forget to warm up the oven to about 325-350 and do the same. It won't hurt the rubber on a stock unit and will require gloves to handle......Watch the posts, these guys will get you there.

Thanks Don, sharper minds prevail.

Hey, my 7000th post.

Hey, where is Denny and some of those fireworks he can put up? 7000, wow. And every one of them a pearl.

You have really given lots of good, accurate info in those 7000 posts. Thank you.


Don

If you did want to use a heli-coil all the depth you need is 1.5 X bold diameter.
And you could use a locking heli-coil, I doubt you would be able to pull one out by over tightening......Heck, they don't like to come out with proper removal tools

Originally Posted by nitrowarrior

Tech? you wanna handle this? Bottoming tap has threads all the way down the shank(or fluting) as it goes in, it does not leave material untouched and will "bottom" out in the end blank (bottom) of the hole . Use a BFH, but make sure it a lead shot mallet, no steel hammers. I can can't see the problem first hand. Follow Tech's instructions. I own the kit to solve this. It is not readily available to the public so I am gonna tell you to go old school as much as I can with you.

Thanks warrior, I didn't see your answer when I posted.

bottom tap. I like the boiling water trick, 325-350 is pretty hot, I usually stay around 225. Does the engine turn in the same or opposite direction of the nose threads ?

I think we oughta pop a cold one in honor of Tech's 7000th post.

Originally Posted by 42K3

bottom tap. I like the boiling water trick, 325-350 is pretty hot, I usually stay around 225. Does the engine turn in the same or opposite direction of the nose threads ?

clockwise threads, clockwise crank as viewed from the front.

Originally Posted by nitrowarrior

I think we oughta pop a cold one in honor of Tech's 7000th post.

PSSSSSSSTTTT. Oh heck, suds all over my undershorts. Just kidding, I don't drink alcohol but thanks for the thought.