1968 Street Hemi build

[rev.ronnie]

I have made more progress on this, but I am between two iPads right now and I don't have email back up and running.

The rods are done, the crank is getting ground to spec and I will resume next week.

 

[2059]

Great thread!! great info!! Keep 'em comin'

 

[rev.ronnie]

Great thread!! great info!! Keep 'em comin'

Thanks, I will be back on this project next week. I have got a little more done, but we were waiting to get the clutch back from the rebuilder. It's here now, with the flywheel, so I can continue on with balancing.

 

[64BEL]

Indexing the block with a BHJ block true. This fixture corrects the deck using the centerline of the crank and cam as datum line reference. The deck surface can then be used as a bore reference. I won't be boring this block however, it is .025" over and I will be honing it to .030.
Notice how far off it is with a .004" cut. It took .010" to correct it.



One side finished, deck is now 10.715". I removed the guards for a better view.



Weighing up bob weights.



Crankshaft on the balancer. I first balance the crank alone. Then add the flywheel and damper and correct them as required. Next, I add the pressure plate and correct it. I try it in all positions to find out where it is closest first. It's amazing that even turning it 90 degrees can change the balance by 25+ grams. I will stamp it for correct position on assembly.



Fun pic of the crank spinning.



Removing material for balance correction. Notice on the computer the amount of correction needed. 65 grams off in the front and 62 in the rear. The computer tells the amount and position of the correction that needs to be made.



Final corrections are made, and the crankshaft is balanced. On to the rest of the parts next. Doing it this way ensures that no bolt-on part, that is not properly balanced, will cause the crank to have that imbalance built into it.
Make sure this is the protocol your shop follows. If a shop bolts the whole assembly on the machine and makes all the corrections on the crank, if any part is replaced later on, the assembly will probably no longer be balanced.

 

[rev.ronnie]

That's for posting these for me Dave! I really need to get a handle on this iPad thing

Well, I finally back on this thing after a month or so of catching up on a ton of Buick stuff. I had a customer who moved his shop and was about 7 engines backed up.


Now the fun resumes!

 

[Meep-Meep]

So I'm curious about your balancing setup. I see that is a hard bearing machine and I understand those do not require a calibration run (I have never used one). Do you take an initial reading then add a trial weight of a known amount and angle and let the computer calculate the correction? I balance stuff too but my stuff goes insanely fast and is much lighter so I have soft bearing machines and a high speed portable balancer. The skinny shaft on the snout must be driving an encoder?

If I understand you correctly, you zero out the crank then use that as a mandrel to balance the flywheel, pressure plate and harmonic absorber.

 

[rev.ronnie]

So I'm curious about your balancing setup. I see that is a hard bearing machine and I understand those do not require a calibration run (I have never used one). Do you take an initial reading then add a trial weight of a known amount and angle and let the computer calculate the correction? I balance stuff too but my stuff goes insanely fast and is much lighter so I have soft bearing machines and a high speed portable balancer. The skinny shaft on the snout must be driving an encoder?

If I understand you correctly, you zero out the crank then use that as a mandrel to balance the flywheel, pressure plate and harmonic absorber.

It is a Hines HC-500 balancer. You program in the parameters like: radius, bearing to bearing, and stantion width and just spin it. The computer tells you the add/remove amount and the position to do so.
You are correct, the shaft with the magnetic attachment is an encoder for position and rpm. This machine is calibrated to give correct correction readings at 500 rpm. That said, you can spin it as fast as you want, but the correction reading would be wrong. I have spun computer disk drying hubs at 2200 rpm.

Yea, in a nutshell, I am using the crank as a "real time" mandrel to correct the rest of the parts.
In fact, the "mandrel" I have for balancing Mopar torque converters is a 383 crank that is balanced to a real simple bob weight setup. I fine tune it to zero with clay, bolt up the converter with a balanced flex plate, true the runout, install the stator centering tool and spin it.

What are you balancing at such a high speed? Turbo impellers?

 

[Meep-Meep]

It is a Hines HC-500 balancer. You program in the parameters like: radius, bearing to bearing, and stantion width and just spin it. The computer tells you the add/remove amount and the position to do so.
You are correct, the shaft with the magnetic attachment is an encoder for position and rpm. This machine is calibrated to give correct correction readings at 500 rpm. That said, you can spin it as fast as you want, but the correction reading would be wrong. I have spun computer disk drying hubs at 2200 rpm.

Yea, in a nutshell, I am using the crank as a "real time" mandrel to correct the rest of the parts.
In fact, the "mandrel" I have for balancing Mopar torque converters is a 383 crank that is balanced to a real simple bob weight setup. I fine tune it to zero with clay, bolt up the converter with a balanced flex plate, true the runout, install the stator centering tool and spin it.

What are you balancing at such a high speed? Turbo impellers?

You are close. I balance turbos but not turbo chargers. My specialty is rebuilding high vacuum turbomolecular pumps. Basically, it's a turbine type rotor with stators driven by an electric motor and it's function is to reduce the pressure in a vessel in the molecular flow range. These things spin, depending on size, spin in the 24 KRPM - 90 KRPM range. These are used to produce products that are part of every day life but few people know what they are because they are part of a larger piece of equipment.

So you just put the crank on and in one spin you have your corrections? Interesting. I have to do calibration runs, so for me to balance something I must make three runs at minimum.

Sounds like you have some awesome capabilities. I never heard of a shop around my area that would balance a torque converter.

 

[rev.ronnie]

You are close. I balance turbos but not turbo chargers. My specialty is rebuilding high vacuum turbomolecular pumps. Basically, it's a turbine type rotor with stators driven by an electric motor and it's function is to reduce the pressure in a vessel in the molecular flow range. These things spin, depending on size, spin in the 24 KRPM - 90 KRPM range. These are used to produce products that are part of every day life but few people know what they are because they are part of a larger piece of equipment.

So you just put the crank on and in one spin you have your corrections? Interesting. I have to do calibration runs, so for me to balance something I must make three runs at minimum.

Sounds like you have some awesome capabilities. I never heard of a shop around my area that would balance a torque converter.

Yes, one spin and you have your correction data. I would like to see your machine. It must be sensitive to read such a light part. Hines makes similar machines, for the same type if stuff.

 

[Meep-Meep]

Ronnie,

Here it is. Using my Swiss Army knife for scale the machine is pretty small as you can see. Under ideal conditions it's capable of up to a minimum achievable residual imbalance of 5 micro inches. Maximum weight per support is 6.6 lbs, so I won't be balancing hemi cranks on this one!

The other machine is a high speed field balancer and can easily measure over 100,000 RPM. I won't get into too many details on a public forum because what I do is highly proprietary. It's not you I'm worried about but everyone else connected with my industry who may happen to stumble upon this post.

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The pump pictured runs at 42,000 RPM and when I'm done balancing you certainly won't feel it and will have to get really close to hear it running. In a typical room with some normal office or lab background noise you won't even know it's on, and this is what my customers like as opposed to my competition.

 

[rev.ronnie]

That is very cool. I remember seeing a picture of John Meyers balancing a turbo impeller/shaft once and it was a Hines machine that is even smaller that that. That must use ceramic bearings if it is a true 'soft bearing" balancer.

I have a 60 cc Kitty Cat crank I want to balance. I think I have to put heavy metal in it but my machine won't pick it up because it's too light. I made a bob weight for it too. I need to find a machine like that around here!

 

[Meep-Meep]

The ceramic ball bearings are actually in that pump. The term "soft bearing" has to do with the type of work support on the machine. Each support is mounted on a flat spring and moves easily thus providing very good sensitivity making it ideal for small parts. I have another soft bearing machine that is good up to 30 lbs. The 30 lb machine isn't terribly expensive and if you're interested PM me and I'll give you the info. on where to get one.

 

[rev.ronnie]

Coincidentally, all the soft bearing machines I have seen have roller bearings on them VS hard blocks. The older ones let the spring mounted cradle move and it is mounted to impedance or current generators. The more they move, the more current they generate and the higher the needle reading. The needle reading must be converted to grams. Mine just tells you in grams. Now, I've always wondered if I were balancing a light part, like if a crank were made of aluminum, hypothetically, would the correction reading be off?...I don't know. Probably not because it would show less imbalance at the same spot because of less weight.

I have done CNC machine spindles with no problem. The outer body sits on the bearing blocks and the inner spindle spins inside of it. Kinda funny to do.

I don't really do enough light stuff to really worry much at this point. I do my boat propellers and snowmobile clutches no problem.

 

[Richard Cranium]

Almost looks like you know what you're doing.

 

[Meep-Meep]

Coincidentally, all the soft bearing machines I have seen have roller bearings on them VS hard blocks. The older ones let the spring mounted cradle move and it is mounted to impedance or current generators. The more they move, the more current they generate and the higher the needle reading. The needle reading must be converted to grams. Mine just tells you in grams. Now, I've always wondered if I were balancing a light part, like if a crank were made of aluminum, hypothetically, would the correction reading be off?...I don't know. Probably not because it would show less imbalance at the same spot because of less weight.

I have done CNC machine spindles with no problem. The outer body sits on the bearing blocks and the inner spindle spins inside of it. Kinda funny to do.

I don't really do enough light stuff to really worry much at this point. I do my boat propellers and snowmobile clutches no problem.

Oh, I get what you mean. Yes, I have a set of roller work supports for it. They are not ceramic ball and are probably just ABEC 3 runout tolerance - nothing fancy.

The process of converting the meter reading to grams is done in the calibration run. You take a known quantity of mass and place it at a known radius and using this formula: Calibrated weight x radius / balance tolerance in gram-inches gets you the meter reading. You also need to establish good plane separation. I'm not familiar with hard bearing machines but I do know they measure force as opposed to displacement.

 

[rev.ronnie]

Almost looks like you know what you're doing.

I'm making it up as I go along, just like with sex. I just tell the other person involved its good for them. :icon_thumright:

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Oh, I get what you mean. Yes, I have a set of roller work supports for it. They are not ceramic ball and are probably just ABEC 3 runout tolerance - nothing fancy.

The process of converting the meter reading to grams is done in the calibration run. You take a known quantity of mass and place it at a known radius and using this formula: Calibrated weight x radius / balance tolerance in gram-inches gets you the meter reading. You also need to establish good plane separation. I'm not familiar with hard bearing machines but I do know they measure force as opposed to displacement.

Ok, I remember using a Stewart Warner balancer that was calibrated that way. You would run it up, then add a known weight to a measured radius (usually clay) and then re-spin to get the difference and calculate as you say.
I will say that my machine has me spoiled. It wasn't cheap, but it's accurate and fast. The next and final time I move the shop, I'm getting a new one. I've been real happy with Hines machines.

 

[64BEL]

Honing the Hemi block.


Flywheel and pressure plate balanced. Notice the weight I had to add.



Rotating assembly installed.


The shortblock, assembled. I just did a minimum blasting on the outside for repainting and left all the factory paint marks on the inside, so it's not real pretty.


Another pic, factory paint splotches and all.

 

[rev.ronnie]

Thanks for posting these Dave! I have a new laptop, so once I figure it out, I'll be in photo posting heaven

 

[benno440]

thats nice.

what a great setup you have there

 

[64BEL]

No problem, Ron!