Crankshaft Balancing Question

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GR5

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Hi All,

I came across a ‘69 340 crankshaft that at one point was balanced with blobs of weld. Is this an acceptable way to balance a crankshaft? I have never seen this before.

Thanks,

Mike
 
The blobs of weld have probably welded on some Mallory metal. Would have to see pictures. But yes, that's how it's done.
 
0E4A029A-6484-481C-B515-2224609F24F9.jpeg
I do have a photo.
 
Dangit, that's purdy ugly. If that was mine, I'd grind all that outta there and start over....OR find another crankshaft. That's rough. Generally that's not HOW or WHERE it's done. Holes are drilled into the side of the counterweight mallory metal is pressed into the hole(s) and then welded in. No way I'd trust all that swingin "out there".
 
Here's what it should look like. When done correctly, no welding required. They are pressed in.

MALLORY METAL.jpg
 
Never seen anything like that, that is ugly for sure.
 
I had a spot like that on my pressure plate when the entire rotating assembly came back from balancing. This was back in the '70's.

Later, when I returned the pressure plate to the manufacturer for rebuilding (i think it was Mcleod) they said that would not honor their warranty if I did that again. I never did ask the balance guy about it.
 
There's nothing "wrong" with it, but yeah it's crude and ugly. My impression is it would be fine, but you need to know why it needed all that metal - your use might mean that has to be drilled out to remove weight...lol.
 
If there is no heavy metal slug under there, and just a weld of some added weight for a small adjustment, then that is acceptable.

If there is heavy metal under there, it could be better done but is not the worst direction; centrifugal force is not pulling straight out on the slug.
 
dibbons said:
I had a spot like that on my pressure plate when the entire rotating assembly came back from balancing. This was back in the '70's.

Later, when I returned the pressure plate to the manufacturer for rebuilding (i think it was Mcleod) they said that would not honor their warranty if I did that again. I never did ask the balance guy about it.
Click to expand...



That's because the McLeod covers are heat treated. Weld on them and they crack.

There are MUCH better ways to balance a pressure plate than welding on it.
 
nm9stheham said:
If there is no heavy metal slug under there, and just a weld of some added weight for a small adjustment, then that is acceptable.

If there is heavy metal under there, it could be better done but is not the worst direction; centrifugal force is not pulling straight out on the slug.
Click to expand...


That's a weird place to need to add weight. Where the weld was added was light. That means about 180 out it was heavy.

When I see **** like that, I question the whole balance job.
 
Thanks all for the replies. I had a feeling this wasn’t correct. I’ll have to get in touch with a local machine shop and have them check it out.

Unless, do I just look at getting a new crank?

Thanks,

Mike
 
nm9stheham said:
If there is no heavy metal slug under there, and just a weld of some added weight for a small adjustment, then that is acceptable.

If there is heavy metal under there, it could be better done but is not the worst direction; centrifugal force is not pulling straight out on the slug.
Click to expand...

No but it sure would be better done "correctly". I have seen some OLD NASCAR and NHRA stuff at swap meets before that looked similar and worse. It worked. It'll still work, but it's kinda like camshaft technology. It's come a "long way".
 
GR5 said:
Thanks all for the replies. I had a feeling this wasn’t correct. I’ll have to get in touch with a local machine shop and have them check it out.

Unless, do I just look at getting a new crank?

Thanks,

Mike
Click to expand...

If it's going to bother you, what I would do is disassemble it, get the angle grinder out. You can get a nice diamond tipped cutting wheel. I would do that and cut "all that" off as close to the outside edge of that counterweight as I could, then see "what's left". Problem is, that hole has been completely filled in "with something" and you don't know if it's all weld "or what". When you get the weld cut off, it might all let go and come out. Then again, if whoever did it welded to fill the entire hole in, then........well......LOL

340 cranks can be had reasonably. I guess you're going to have to make a decision at some point. "I" would try to get that off if it was mine. What have you got to lose?

If you take it to the shop they are going to have to do everything except put weights on or take weight off to check the balance. In other words, you'll basically be charged for a balance job. Even if it checked out good, you're money out at that point and "I" still would be leery of "THAT". lol

You can say whatever you want about centrifugal force, BUT if that lets go while running, all theories now become a nasty reality.
 
yellow rose said:
That's a weird place to need to add weight. Where the weld was added was light. That means about 180 out it was heavy.

When I see **** like that, I question the whole balance job.
Click to expand...

I would not personally worry too much about the weight... I'd worry about the what this was balanced for and how it would balance with the new parts I was going to use with it.

BTW, OP, are there holes inside in the 1-2 and 7-8 crank throws, drilled parallel to the axis of the crank and from the front on 1-2 and the rear on 7-8? That is a 340 crank. I have to wonder if this is a 318 crank modded to be used with 340 parts.
 
nm9stheham said:
Which would need to be re-balanced for standard 340 parts....
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If you really want to get tricky you can use a 273 crank but it takes a bit to get it balanced.

I used lots of them, but I was running aluminum rods and had a bobweight that was under 2000 grams.

I've also turned the counterweights down (need a damn rigid lathe or a crank grinder) to almost the rod throws. Takes some Mallory to get that balanced.


You can do some serious mental mastubation on this stuff and end up spending a bunch of money on things you can't really prove effective.
 
I'll say this.......ugly as ****, you bet, you don't know anything about the previous build so you don't know the "why".......pretty don't make it better, it's just pretty
 
nm9stheham said:
I would not personally worry too much about the weight... I'd worry about the what this was balanced for and how it would balance with the new parts I was going to use with it.

BTW, OP, are there holes inside in the 1-2 and 7-8 crank throws, drilled parallel to the axis of the crank and from the front on 1-2 and the rear on 7-8? That is a 340 crank. I have to wonder if this is a 318 crank modded to be used with 340 parts.
Click to expand...

Well yeah all that kinda goes without sayin.
 
JBurch said:
I'll say this.......ugly as ****, you bet, you don't know anything about the previous build so you don't know the "why".......pretty don't make it better, it's just pretty
Click to expand...


That's what I asked several posts ago. I've done many balance jobs and never once did I need to add weight there. That's a strange place to add weight.

Like maybe the F'd up and added weight in a hole that didn't need it, so they added weight out there.

I've seen some **** balance work. I trust nothing when the job looks like that.
 
having had a chunk of mallory come out under a weld like that and completely destroy a block and break the cam ...and the cam tunnel- cylinder walls...
high buck road race build
then again why would there be mallory in that spot in the first place?
if there is no mallory that's another story no big deal\ now who can tell?
 
Thanks for the replies.

I just spoke to a local shop and I'm going to take the crank in and have it checked out. As some have said it may be okay, but it may not be. I'd hate to ruin something which would cost more money.

Mike
 
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