balancing holes ?

[rmracing]

Could having alot of big holes in the crank from balancing be bad ? It just looks like a nice place for oil to get up into or will it just sling it back out ? Would it be better to grind the crank weight down to balance v/s drilling big holes or does it even matter .

[Crutch]

I would think turning down the counter weight, where applicable would improve the "polar moment". FWIW

[79rallysport]

^actually I think you mean "mass moment"; the tendency of an object to resist rotation.

[Keith Morganstein]

Drilling allows metal / weight removal in a specific spot.

like balancing a wheel, you want the balancing weight in a certain spot, not spread out uniformly over half of the wheel.

[rmracing]

Drilling allows metal / weight removal in a specific spot.

like balancing a wheel, you want the balancing weight in a certain spot, not spread out uniformly over half of the wheel.

I see what your saying , but my crank has big holes drilled all across the weight .It actually has so much drilled out it looks like they could have just cut the whole lower part of the weight off. I am just wondering if this could hurt any power at all do to windage or oil getting up into the holes.

[Wolfplace]

Drilling allows metal / weight removal in a specific spot.

like balancing a wheel, you want the balancing weight in a certain spot, not spread out uniformly over half of the wheel.

I see what your saying , but my crank has big holes drilled all across the weight .It actually has so much drilled out it looks like they could have just cut the whole lower part of the weight off. I am just wondering if this could hurt any power at all do to windage or oil getting up into the holes.

=
I always cut the counterweights down to get a crank close if it is out much & finish with a couple of holes if necessary.
I have done it in a lathe, mill, even cut the end off a counterweight with a bandsaw if necessary to get them within reason.
But I also don't balance an engine for $100 either

I have seen some of the cranks with a bunch of damn holes drilled into the counterweights & to me it looks like crap, but in the real world it probably does not hurt anything, the oil will get thrown off

In my opinion,, anyone who balances a crank like that has absolutely no pride in what they are doing.

[Baprace]

rmracing, I'm assuming you have a sbc 350 with a one piece rear seal.

[rmracing]

rmracing, I'm assuming you have a sbc 350 with a one piece rear seal.

Its a 302 ford with a scat superlight crank. It has very light rods and pistons . Even with zero balancing it , they still had to take lots of metal out.

[Ed-vancedEngines]

I am not a balance Ghru. I have never balanced a crank in my life, but If it is as you say with holes all the length of the counterweight, it does seem reasonable that cutting the counterweight Od down a certain amount would make sense, if you still get it re-balanced or do a re-balancing.

As far as the drilled big holes removing a specific amount of weigth from a certin spot, I agree. I have however seen cranks that had like a V shaped notch cut out in a certain spot to remove the weight and the edges of the cut was rounded. I can not remeber for sure, but I think it was on a Six-Pack 440 Steel Crank is where I saw this. Just another way of doing it I guess.

Ed

[C Stevens]

Don't worry, the oil will NOT stay in the balance holes when the engine is running. Fill a glass with water, sling it around with the open end out, See?

[Baprace]

rmracing, I wonder if the balancer and flywheel counterweights were correct I am doing an aftyermarket small block ford now, ( not sure of the actual CI ) as I am only balancing the crank with the customers weight numbers but the customer gave me an aftermarket balancer and flywheel which are marked to be 28 inch oz's instead of 50 , and I found the balancer WAY over counterweighted , the flywheel end was ok but the balancer was way off, it had a removeable counterweight so I just reduced the width of it by .325 and with two little holes in the front & rear counter weights and I was finished. This is just the way things are made today, no quality control.

[Cfin]

Rmracing, I know where you are coming from as I have a similar setup getting done shortly and know a considerable amount of weight has to be taken out of the CW's. I was told that it makes no difference removing the weight using the multi-hole method but boy does it look ugly and I am sure it won't help the aerodynamic quality of the crank.
I think I will spend some time finding a shop that will grind most of the weight off first.... to me it should reduce the actual circumference alittle and look "better", even if it does cost alittle extra.

[Dave Koehler]

External H balancers and flexplates.
Having spun a few up over the years it is amazing and how sad it is on how far off most of them are from the factory spec. Especially the stock replacement type parts. The ones coming out of India are horrible. Perhaps even worse than China. The time zone difference must make a difference in the read outs.

The best replacements as far as weight is concerned have been the ones coming out of Australia..most of the time. Stuff does happen.

As far as race versions are concerned ATI hits it right almost every time. Fluid Dampners and ProRace (again Aussie) do well also. The rest are a big disappointment but they generally also exhibit bad machinework and have a history of falling apart anyway. Meow!

Funny thing is that the OEM replacements aren't much better when it comes to the weight. I have come to the conclusion at least as far as GM is concerned that we do not get the "first pick" parts as replacements over the counter.

Having an SFI sticker attached does not magically fix an incorrectly weighted part either.

I will refer to flexplates for the moment. The saddest things is that regardless of what country produces the item or whose name is attached it is unusual to find 3 flexplates in a row that match. I don't mean just a little different. A lot of times it's a lot different. Pretty sad.

The only cure is to internally balance everything but since that is not possible in every app I suggest spinning those parts up first to see if you are going to have some extreme grief finishing the job. You may want to correct the parts before continuing.

For what it's worth I don't blame a particular country for some of the junk we see. I blame the idiot that is located here and wrote the specifications and didn't pay for the quality control option.

Dave Koehler

[Ed-vancedEngines]

Hey Dave,
Have you also checked any or many of the Innovators West Harmonic Dampeners? I have been using those from time to time.

That info you supplied is eye opening for me. Thx.

Ed

[Dave Koehler]

For whatever reason I have never had an IW or a BHJ and maybe a couple of others come through here so I do not know.

Something else you want to check is those add on flywheel wings for the chebbies. Scary

I asked one flexplate mfg where they found their CW specs for engines that are not published by the OEM. The answer was "We just buy 10 from someone else and average it". I then asked what their new found averaged spec was for a specific engine and I could not get an answer. Hmmm I wasn't surprised by this because I never had 2 items from them that matched.

To throw another wrinkle into this deal. Most of us use the plus and minus figures given to us by the balancer equipment mfgs. These are all copied from Stewart Warner info from way back in time. 60s and earlier?
Are they correct? I ask this because even the oems seem to have a wider spread on the spec that we try to adhere to and darned few of the oems publish this info.

It would be nice if these items were more consistent across all mfgs but that is why we balance these things. To find and compensate for all the variables. In the end, while aggravating, it does create work for us. One just has to learn to charge appropriately.

Dave Koehler