72 C-20 Harmonic balancer

[saddletramp]

Afternoon Guys im swapping out my harmonic balancer on my 350 motor the Key way on my crankshaft is alittle worn the new key is tight on the new balancer will this still work or am i toast any idea,s Thanks Saddletramp

[morepwr]

As long as it still has some register in the crankshaft you should be just fine. As long as the balancer fits the crankshaft tight and you use a good bolt on the snout I would run it.

[BCOWANWHEELS]

I,d fill the void in the crank with jb weld b4 I install a new balancer personally then I,d start hunting for another crank

[jocko]

You "should" be fine if the slot is intact at its base - the balancer will retain the key. The bigger question is how did the crank get worn like this? That is what would worry me personally. If you don't know (and you probably don't), I'd have to assume it is wear (and it looks like wear, smooth surface, appears wallowed out), which is not a normal thing to happen in that area. Key damage is more common, but this crank wear would concern me a little - because it will continue. If you're planning to keep driving it, it might be a rebuild candidate in the future. What happened to the balancer that drove you to replace it? If you were having balance issues, it may have been more than the balancer. Anyway, if the key is firm at the base of the slot, the balancer will retain it, and I'd drive it. But it is an issue that will likely eventually need to be addressed.

[Steeveedee]

Originally Posted by bcowanwheels

i,d fill the void in the crank with jb weld b4 i install a new balancer personally then i,d start hunting for another crank

x2

[saddletramp]

Evening Guys When i got this truck the harmonic balancer was all over the place so i dug into it found that the balancer came apart where the key would sit and it tore up the front timing crankshaft seal the guy i got it from must have run it like this for a while I cant complain the truck was free the just said to me come and get it im going to try and weld up the area where its wallard out here the balancer i took off Thanks for the help Saddletramp

[AussieinNC]

Check the other key on the crank, the one inside the cam drive gear....it looks like it chewed up as well.

This damage is usually caused by a stripped out crank nose thread or the bolt has been left loose....

[RustyPile]

Originally Posted by saddletramp

Evening Guys When i got this truck the harmonic balancer was all over the place so i dug into it found that the balancer came apart where the key would sit and it tore up the front timing crankshaft seal the guy i got it from must have run it like this for a while I cant complain the truck was free the just said to me come and get it.. I'm going to try and weld up the area where its wallard out here the balancer i took off Thanks for the help Saddletramp

You can't just "weld up the area where its 'wallard out'.. "... It can be welded up and a new keyway machined in, but it's a precision process that should be done by an experienced machinist equipped with the proper skills and tools..

[saddletramp]

Heys I went looking for my Harmonic balancer bolt that goes into the Crankshaft I went to Advance Auto for a ARP bolt i have a 350 Chevrolet small block the bolt came up on the computer was 7/16 ×20 not even close to the bolt i took out of my engine the guy at the counter put in a 402 big block and it came up with a 1/2 ×20 it matches my bolt so any idea,s why the numbers on my block matches a 350 could this be some one put a bigger crankshaft or taped and dyed this crankshaft?? Thanks Saddletramp

[RustyPile]

Sounds like there's been previous problems with the crankshaft/balancer in the past.. The washer on your old bolt is wrong also.. You should have a very thick tight fitting washer.. There's nothing wrong with using the next size bigger bolt, but you need to do something about the keyway in the crankshaft.. I've never been a fan of "patching" keyways.. I suggest you either get another crankshaft or take your existing one to a reputable machine shop and have it repaired..

[Steeveedee]

They probably stripped the crankshaft threads and drilled and tapped for a bigger size, is all. Probably tried to put the new balancer on after a timing chain change and used too short a bolt. The correct length bolt would use all the threads in the crank and they wouldn't have pulled out. Just my guess based on experience. It's an old engine. I've worked on engines from '68 that had those kinds of problems in the mid-'70s, fwiw. The key way may have been damaged by some "Bubba" hammering at the balancer until it bottomed against the crankshaft.

Classic example- I worked at a parts store in the late '70s and we had this guy at a customer's shop doing brake work. He had ordered 1/4" vacuum hose and clamps, and was complaining that they kept popping off. Since I had the most mechanical experience, they sent me over to see what he was doing. He was using the hose and clamps to repair brake lines. SMH

[RustyPile]

Originally Posted by Steeveedee

They probably stripped the crankshaft threads and drilled and tapped for a bigger size, is all. Probably tried to put the new balancer on after a timing chain change and used too short a bolt. The correct length bolt would use all the threads in the crank and they wouldn't have pulled out. Just my guess based on experience. It's an old engine. I've worked on engines from '68 that had those kinds of problems in the mid-'70s, fwiw. The key way may have been damaged by some "Bubba" hammering at the balancer until it bottomed against the crankshaft.

Classic example- I worked at a parts store in the late '70s and we had this guy at a customer's shop doing brake work. He had ordered 1/4" vacuum hose and clamps, and was complaining that they kept popping off. Since I had the most mechanical experience, they sent me over to see what he was doing. He was using the hose and clamps to repair brake lines. SMH

Back in my days working on the line, we had a name for guys like that.. No-brained iron thumb..

[saddletramp]

Morning Guys Thanks for the help appreciate ya. Saddletramp

[saddletramp]

Afternoon Guys I welded up my Crankshaft Key way today hope it works cant afford to replace the Crankshaft right now i said a prayer to the Crankshaft Gods Saddletramp

[Steeveedee]

Originally Posted by saddletramp

Afternoon Guys I welded up my Crankshaft Key way today hope it works cant afford to replace the Crankshaft right now i said a prayer to the Crankshaft Gods Saddletramp

The gears look like they have a lot of life left, so if things aren't flopping around you should get a good long use time. :thumbsup:

[saddletramp]

Afternoon Guys I got my harmonic balancer bolt today from Summit the washer that comes with it is bigger that the center hole on my pulleys can someone clear this up for me i no the pulley,s bolt to the harmonic balancer right if i install the bolt now over the pulleys the bolt will not have anought threads in the harmonic balancer and i will end up with the mess i just fixed so do i need to make the center hole in my pulleys bigger is that the right way it goes ? Thanks Saddletramp

[Ironangel]

The "outside" washer diameter for small block Chevy cranks is 1.98" inches in diameter. The center hole in the pulleys should be slightly larger at 2"...Three 5/16" bolts for the pulley(s) ...Don't mess with the pulley(s)! Grind the outside diameter of the big block 1/2"x20 WASHER down to 1.98" or just shy of 2" in diameter and you should be good to go...Good job on the welding and grinding, make the washer fit the hole/indention in the dampener...Use 2 either grade-8 or grade-5 1/2" washers if you have to because the washer and the bolt length locate the dampener on the crank, that's very important! The bolt and 3/16" thick washer must be used to push or suck that dampener on tight, it's a tight interference fit. NEVER use a hammer to install a dampener! The bolt length for SBC cranks is 2.47" inches, if that crank wasn't drilled and tapped to that length you may have to shorten the bolt. Judging from the pic that hole and threads looks like its only partially drilled and tapped...No big deal, just measure the distance you can screw that bolt into the crank, subtract that distance from 2-1/2" and that's how much you need to cut off the new 1/2" bolt. It would be best to drill and tap that crank the full 2-1/2" and use the full length of the grade-8 bolt in the hole...That use to be a 7/16" bolt hole, it's been drilled and tapped for 1/2-20...

[saddletramp]

Afternoon Guys I finaly got out to my shop to install my harmonic balancer it didn't go well i put the key in the slot it got bound up during the install it was real hard to turn the bug nut on the install almost to the end so i had to remove it the key got hung up and tore up the timing cover seal before i try it again where should i put the key in the slot on the crankshaft our put it in the harmonic balancer channel where it rides? Thanks Saddletramp

[notsolo]

Could be the photo but the key looks to be tilted slightly.

[toolboxchev]

Yea, tilted in the pic for sure. Grind that area that was welded some more just below the surface of the circle of the outside diameter of the crank snout.

You can use a Dremel tool for the finer stuff. Or a piece of Emory Paper.

Take your time with a inexpensive installation tool using a Black Marks A Lot pen to show the high spots (if any).

If it stops going on with the install tool, pull it off and you will see marks where the black pen mark got wiped off. Those are high spots.

[RustyPile]

Yep, the key is sitting crooked.. Using a 2 LB ball peen hammer, drive the key into the key way until it's tight.. Using a belt sander, grind the exposed part of the key until it's square with the keyway on the balancer.. Install the balancer using an install tool.. If the tool stalls out, hit on it with a hammer as you turn the wrench to help it along.. You'll get there.. Just use some heavy duty redneck ingenuity.. smh..

[saddletramp]

Thanks for the Responses ill be back in the garage this weekend to try it again appreciate ya all

[saddletramp]

Evening Guys can i get some help ive installed my second balancer i have a 72 C-20 with a 350 the balancer bottom,s out a inch before it buts up against the timing cover seal also is the balancer suppose to be flush with the crankshaft snout does anybody have a part number of the right Harmonic balancer i have auto zone , O'Reilly's, and Napa in my area Thanks Saddletramp

[MARKDTN]

Originally Posted by saddletramp

Evening Guys can i get some help ive installed my second balancer i have a 72 C-20 with a 350 the balancer bottom,s out a inch before it buts up against the timing cover seal also is the balancer suppose to be flush with the crankshaft snout does anybody have a part number of the right Harmonic balancer i have auto zone , O'Reilly's, and Napa in my area Thanks Saddletramp

Dorman 594-012. Most of the parts houses can get. Might also go visit Mikes machine shop if they are still around-maybe they have a decent used one. Or one of the many junkyards in M'Boro. That balancer is not uncommon-fits like 69-98 SBC. If you were local I'd give you one.

[GASoline71]

If you're using the crank bolt to run the balancer on... you're either gonna snap it off in the crank, or strip the threads again. There is a balancer installation tool to do the job.

Also, I'd also be concerned with how long that old balancer was actually run on the end of that crank. A wobbly balancer can wear out bearings over a short amount of time.

Gary