6 cyl harmonic balancer bolt size?

[eric67m]

I have pulled the harmonic balancer and timing cover off of my L6 292 this past week. I have started to put everything back together but can only swing my "installation hammer" so far because the radiator is still in the truck. I tried to use the bolt from the harmonic balancer/crank to pull the balancer back on. It will tread only so tight before it pulls loose. I tried a new 7/16 X 20 bolt like the one that was in originally but slightly longer and it does the same thing.

My question is.... is this the proper bolt size and thread or is my crank stripped out? And how can I get my balancer back on?

[Fred T]

Sounds like the crank is tapped for a 1/2-20 bolt. Get one at the hardware store and try it. If it works, great. If not, drill with a 27/64 bit and tap with a 1/2-20 tap.

Pulling a damper on with a bolt is risky business. It is very easy to break the bolt in the hole. Be sure to lube the threads and crank snout with anti-sieze. You will probably also have to get a bolt that is an inch or two longer to start the damper on with. A damper installation tool is best. Here is one example.
http://www.lislecorp.com/tool_detail.cfm?detail=959

[eric67m]

Thanks for the advice. I will try that out tomorrow. I would assume the install tool is better because it threads the stud all the way in first assuring full thread contact and then runs the nut and washer assembly in after. Maybe I would be better getting a stud or all thread? I will see what is available at the hardware store. Thanks again.

['68OrangeSunshine]

Stock 292 crank snout HB bolt is 7/16 -20 UNF x 1" deepthread. Total bolt length is 2-1/2" long. Leo Santucci recommends a 1/2 -20 UNF x 1" deep minimum thread. Except for the shorter lengths these are the same relative sizes for the SBC and BBC HB bolts. The 1/4" thick washer is the same.
Using the special tool is the only way to go. I got a new one from Eastwood for under $40. You might be able to rent (borrow) one from an auto parts store, but they don't always have all the pieces in the box later on down the line.
Good luck and use lots of clean motor oil.

[Fred T]

A stud or all-thread is better than using a bolt. If you go this route, make sure the damper is going on straight, and be gentle when turning the bolt.

The installer tool is far better, it's designed to take the shear load off the bolt when it seats against the crank snout. This lowers the chances of breaking the bolt in the crank, which is tough to repair. Problem with the installer is it's about 6" long, usually too long to use with the radiator in place.

Anti-sieze works far better than motor oil. It does a superior job of reducing friction, and it in the finer threads better. I have used both and prefer the anti-sieze. It has one drawback, it's what I call a nasty lube. Tough to get out of clothing and it's difficult to clean off parts. Apply it sparingly, I prefer an applicator brush, which you get in the lid of the bottle. With the smaller tubes, I would use an acid brush. For cleanup I use a can of spray carb cleaner.