Dang it dang it DANG IT! Ruined 454 Crank Snout

[93FatBottom]

Well in my attempts to remove the crank sprocket to upgrade to double roller, I managed to cross thread the harmonic balancer bolt in my 1984 454. I am so pissed at myself I can't even believe it. I oiled the bolt first JUST to avoid this kind of thing, the bolt threaded in (or so I thought) and i couldnt turn it by hand so I used a wrench. It was getting tough to turn but i figured it was just by design, so I slowly continued. The bolt went half way down before It got stuck, and when I backed it out to investigate, powdered forged steel and ruined threads came out with the bolt. NOW I have to order a new crank, and I am just FURIOUS. I'm about to throw the motor off a bridge. It's one of those days.

The motors got 30k on it. Should I do a full rebuilt since the crank has to come out anyways, or should I just order the new crank and drop it in as is, maybe with some new main and rod bearings. Though this IS a good excuse to completely cover my bases, I'm still a little irritated, GOD I wanted this freaking truck on the road. Now I get to wait even LONGER.

[jhngardner367]

Depending on the depth of the thread damage,there are some alternatives to replacement,that I've had good luck with.
If it's only damaged 1" or less,use a bottoming tap to clean it,and get a longer bolt,OR have it drilled and tapped for either heli-coil,or a larger,full-length bolt.
The other option is having a machine shop weld it in,and re-cut the threads.
I've saved more than one,this way,including a blown/injected 426 hemi,pushing 800hp!

[Telecasterjoey]

I'd drill it out and tap it the next biggest size! New bolt, crack a beer!
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[raceman6135]

I agree with the "tap it the next size larger" theory. I've done that before and didn't even have to drill the hole larger. Twenty-five cents for a new Grade 8 bolt and you're ready to race in less than a half hour.

[Corts60]

This is how we learn and gain experience my friend. Don't kick yourself too hard. We've all done it.

[wyattglock]

No big deal if you drill it out and tap it to the next size. I can say I have ripped the threads out of enough holes to be good with a tap. Sucks, but it is a good learning experience.

[bmchevy1979]

Originally Posted by wyattglock

No big deal if you drill it out and tap it to the next size. I can say I have ripped the threads out of enough holes to be good with a tap. Sucks, but it is a good learning experience.

My Grandpa bought me a short set of wrenches just to keep me from over tightening things and stripping the threads
I wouldn't try to it just happened. Never new my Blazer didn't have power steering until my grandpa drove it I was used to old tractors

[jhngardner367]

AND...It can be done with the engine still in the truck!!!

[93FatBottom]

Thanks for all the replies guys!

I ended up being able to just re-tap the threads to the original size. Half of them were ruined, but after pulling all the large pieces of metal out of the hole, some WD-40 and a couple cycles with the 1/2"-20 tap in my set, the threads are as good as new. I'm definitely thankful for the words of encouragement here though, you guys are great! I felt like a real moron. I'm now in search of the proper tool to install the new crank sprocket for my double roller, and I'm having a heck of a time finding the right tool -.-;; All the shops I call say they don't even have the tool. The shop I was at yesterday just smacks it on with a brass hammer or a mallet. At least the shops my friends work at go through the trouble of heating up the sprocket so it slips on easier, though I'm not exactly sure that's the proper way to go about it either haha.

Does anyone have any tips? I've never had to do the crank sprocket.

On the positive side, once I get this crank sprocket on and set my timing (my crank spun while pulling the old sprocket off, thus throwing it off timing with the camshaft) and I'm ready to bolt everything back together and get ready to give the motor a good coat of Chevy Orange and Flat Silver

[Your41Plague12]

A brass hammer might be the best option there since it's a soft metal. I've never done it before though.

[chebyshortbox65]

Build one out of a piece of tubing get some tubing that fits over the crank snout cut it down and weld a plate on the end and tap the gear gome
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[hatzie]

NEVER drive anything on the end of a crank with any type of hammer. The babbit thrust bearings on one of the center mains is too soft to put up with any type of sharp blows.

Use 1/2" x 20 all thread, 2 washers, and 1/2" x 20 nut. Grease up the washers and bottom the all thread in the snout.
Weld heavy plate over a piece of heavy wall tube. Be sure the tube fits over the snout with the key in place. Drill a 5/8" hole in the plate to pass the all thread through.

[Irish's_79_Step]

Just another tip for the thread issue. I have had great luck with this stuff called helicoil. When you get it, it tells you what drill to use, and provides its own tap. then you thread the coil into the hole, and it'll use the stock bolt. and will be stronger than the original threads (from the manufacturers description).

[93FatBottom]

Hatzie, that is quite an interesting idea, actually, I never considered that... but too late, I ordered the comp cams installer tool and it has already shipped haha. It'll be here Saturday or Monday. But thanks for that idea, I feel kinda dumb for nothing considering that before haha.

Irish, I've used helicoils for exhaust ports and stuff like that, but I just didn't trust it in the crank snout, considering it has to hold at high rpm's with the harmonic balancer dampening the vibrations. Just seemed like bad plans. No worries though, I blew out the hole with my compressor today and just for good measure I chased the threads one more time, and there was NOTHING on my last run, so I'm confident that the crisis has been averted.

I got working on going through my misc. parts in the bed of the truck that came with it, alternators, smog pumps and power steering pumps. One alternator seems to be alright, the power steering pump is actually in great shape, and pretty much everything else was rusted and trashed from sitting so long in the bed of the truck in the rain. I did find a nice aftermarket air cleaner, chrome with 454 and the corvette flags painted on it, and 2 good quadrajet carburetors too (one is a little old and could use a rebuild, the other looks to be in great shape, it was in a bag taped up hidden under a board) I also found some vacuum lines and both the support as well as the battery tray to run dual batterys, that was pretty cool to find. I'm a little disappointed I didn't find more though. I did find a GM 8 lug wheel with a spare tire a little low on air, and a ford explorer/ranger wheel as well that I sold to a friend for 30 bucks haha. The truck also came with abuncha of chevy parts, lifters, a comp cam, distributor, plugs, wires cap and rotor, all brand new, as well as a full gasket set, all for a small block (the truck came with a 400 small block originally, but since it didn't come with the truck, I sold them all to a friend for 100 bucks for his small block hes building for a 63 C10. I threw a bunch of the old rusted brackets and bolts in the scrap pile for my run next week, and scooped abuncha trash in the can right off the tail gate, I'm hoping to have the entire bed of the truck cleaned out so I can get ready to spray in the liner, after I convert the rust of course

Wait, before I forget, does anyone have any Autometer Speedometer part numbers for a 1980 Chevy truck? My dash is wired for full Autometers and I'm planning on going that route (the plug for the stock gauges still works so I'll run those temporarily until I can afford all my gauges haha) I need an Autometer Speedo to mate up to the original TH400 Speedo Cable in the dash, and I'm having trouble finding the gauge for my application.

Thanks again guys.

[butch86]

Wait, before I forget, does anyone have any Autometer Speedometer part numbers for a 1980 Chevy truck? My dash is wired for full Autometers and I'm planning on going that route (the plug for the stock gauges still works so I'll run those temporarily until I can afford all my gauges haha) I need an Autometer Speedo to mate up to the original TH400 Speedo Cable in the dash, and I'm having trouble finding the gauge for my application

personally i would call autometer and get the part number then let the price shopping begain.