Crankshaft Alignment to Block
 

Long story, but I'll try to be brief. The end objective was to align flywheel housing to the crank flange and measurements here showed a 0.010" difference between sides..9 oclock being high and 3 oclock being low. I figured my flywheel housing was warped.....or the crankshaft was not perpendicular to the block. Put the dial indicator base on the block and indicated/rotated the crank....less than 0.001 on that one, so next I put the dial indicator base on the crank flange and the dial pointer on the rear flange of the block and swept it 180 degrees...0.010" difference!!! What has happened here? Bad alignment of the babbit main bearings when poured or line bored to size? The guy I bought the engine from said the babbit was "original" and all he did was remove shims to take up some of the excess clearance. As luck would have it, I need to shim the housing on the side where the cam hole is in the block, therefore shims here are a certain leak...particularly 0.010 worth. Anyone else experienced this problem? Any known repair solutions? Options?

Thanks,
Robert Smith

Re: Crankshaft Alignment to Block
 

What happens if you stick another .005" shim under the top right mounting bolt?

That should put it within specs of .006" max.

Re: Crankshaft Alignment to Block
 

make sure theres no apparent wear on the block between dowels and pan rail seen when the fwheel housing cracks and flexes causing worn spots....whats most important is what is the flywheel doing relative to the housing I assume you tried rotating flywheel on crank?

Re: Crankshaft Alignment to Block
 

Start with Tom's advice and add more shim as required until you obtain alignment. Take it apart, keeping track of the shims and their location, Then apply a Permatex product called Right Stuff, add your shims where needed, set the housing and tighten.

This product is a gasket maker that will easily hold up to the amount of shim you are describing. I would completely circle the cam shaft opening in the block and then put a bead around the entire perimeter of the mating surfaces effectively bedding the flywheel housing to the block with this product. Clean the parts of oil before you use it, let it set up overnight and you will not have a leak.

I use this product often in the assembly of Model A and pressurized Model B engines. On my own engines, which are for go rather than show, I use this product instead of gaskets. The only gaskets I use are a paper pan gasket and a paper valve chamber gasket....well I guess also a head gasket.

Let me know if you need a photo of the application of the sealer and I will post one.

Re: Crankshaft Alignment to Block
 

Myself I would not be concerned about it, first you must install the correct shims in the top of the housing equal to the thickness of the gasket, there is no way to adjust the 6,o'clock position it will be pulled back by the clutch housing.
The way I see it is that heavy rigid Cone shaped clutch housing when bolted back on would take care of the 9 and 6, o'clock in your situation, I suspect that measurements that are grossly out of spec would be from poor alignment boring of the babbitt.

Re: Crankshaft Alignment to Block
 

Hopefully the front of the engine is pointed down, so any crankshaft endplay doesn't enter into the picture.

Re: Crankshaft Alignment to Block
 

Never shim a flywheel housing on any of the set of 4 bolts that hold it to the block.

All shimming is done on the two ears at the top of the housing.

You do it in two steps,

1. Shim the two ears so 9:00 and 3:00 will read the same, shim stacks will not be the same on either ear. Use what ever it takes for thickness, but you will need .002, and even .001 thousandths shims.

2. Now do the top and bottom, or 6:00, and 12:00. You will add shims, or take out shims, but they should always be the same thickness, weather it is .010, or .001 thousandths, on either bolt.

Now, leave the thing set for 24 hours to see if the flywheel housing will change, and if it does, and most likely will, then adjust again.

What you are trying to do here is get 4 points on the flywheel housing for the transmission to bolt up square, so the main shaft does not bind, and take out the rear main, among other things.

Nothing To it.

Herm.

Re: Crankshaft Alignment to Block
 

Herm, you are going to have to explain to me how shimming the ears at the top of the housing will have any effect at all on the 9 and 3 O'clock positions. I can understand how I can align 12 O'clock with either the nine or the three, but at 9 and 3, I still have a difference of 0.010" and the housing is hard-mounted to the block at those two points. What am I missing?

Re: Crankshaft Alignment to Block
 

Yes, it was about 15-20 degrees off being straight down, and I tapped the crank flange with a soft nosed hammer periodically to make sure the reading didn't change.

Re: Crankshaft Alignment to Block
 

Bob, we have done several hundred Model A engines, and they all had to have the flywheel housings mounted square.

The last pictures is what I ended up with, 9:00 and 3:00 - .001, and +.002 which is .0001-50 thousandths difference.

The 12:00 and 6:00 is .000, and +.002 which is .001 thousandths difference.

Herm.

Re: Crankshaft Alignment to Block
 

Herm, I am also trying to understand this:

"Herm, you are going to have to explain to me how shimming the ears at the top of the housing will have any effect at all on the 9 and 3 O'clock positions. I can understand how I can align 12 O'clock with either the nine or the three, but at 9 and 3, I still have a difference of 0.010" and the housing is hard-mounted to the block at those two points. What am I missing?"

You really haven't explained how using different shims under the top ears will have any effect at 3:00 and 9:00 which is hard mounted to the block. I would think that using different shims placed under each ear would make the ears flex and not change anything at 3:00 and 9:00.

Re: Crankshaft Alignment to Block
 

Because it's bolted near the center and you are measuring near the outside, the shims at the top will change the 9 and 3 o'clock settings.

Re: Crankshaft Alignment to Block
 

I can understand how that shimming the top ears will move the 12:00 position to match the 3:00 and 9:00 position. But if at 3:00 it's higher by .010" than the 9:00 position, I don't see how using dis-similar shims under each ear could make a change since the housing is bolted to the block at 3:00 and 9:00. It would seem putting a shim at the 9:00 position would have the greatest effect.

Re: Crankshaft Alignment to Block
 

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Re: Crankshaft Alignment to Block
 

I can "buy into" your and Tom's explanation that the housing does flex and shimming at the top ears can move the outside surfaces...but do you think it is realistic to expect to move those surfaces enough to make all points within 0.005" ? I guess to quell my own curiosity, I'm going to put the housing back on and play with moving the top tabs while indicating the surfaces at 3 and 9 to see if there is any movement. All I've been able to do so far is bring the 12 position into alignment with either the 3 or the 9, but not change or effect the values at 3 and 9.

My temptation is to mount the housing to a large aluminum plate, for rigidity and support, at the bellhouing interface and then toss it up on the milling machine, shim it to remove at least .005" from the high side and resurface the face that mounts to the block. I realize this "mates" this housing to this block forever, or until the main bearings are refurbished, at which time, it may necessary to reface the housing again......:)

Re: Crankshaft Alignment to Block
 

"but do you think it is realistic to expect to move those surfaces enough to make all points within 0.005"

Sure it is done all the time.
Keep trying....way less work than the machining you are speaking of

what variety of shim thicknesses do you have available? You usually have to make your own from various shim stock. Having just the .010 ones on hand from the vendors usually is not enough. Perhaps this is where your trouble lies.
Herm says he has had to go as thin as .001 but we have never had to use less than .005.
I buy shim stock from McMaster Carr; there are other vendors; I am sure eBay/Amazon has various thicknesses as well.
Sometimes you can take main bearing shims and cut them up for what you need.
Use a pry bar carefully under each ear to make clearance to get the shims in and out.
Be sure to torque the top 2 bolts to the specified torque, and not just 'make them tight'
They should be the same torque as the other 4 which I believe off the top of my head is 50-55. Once I determine what shims I need, I use a very thin layer of black RTV as 'glue' to hold them in place (after a final torquing of course), since those 2 bolts are gonna have to come out before you install the engine since most of us install the accel. bracket after the motor is in. And without the accel bracket in place, the stock bolts will be too long so we keep a pair of shorter ones on hand for all this setup we are talking about.

There is a poster on here who had a total engine rebuild several months back and after re-installing the engine and his rebuilt tranny found that the tranny was jumping out of gear. This shim setting up procedure had somehow been overlooked, and evidently they shoved a .010 shim under each ear after everything was all back in the car. Only problem is, this can hardly be called 'dialing in'. No doubt the engine will have to come back out of the car for proper setup

Re: Crankshaft Alignment to Block
 

Think of it in 2 parts.

1. you are going to twist the housing to get 9 and 3. with maybe a different amount of shims, on each ear.

2. You are then going to bring the housing straight in and out, at the top, with the same amount of thickness of shims to get the housing at 12 and 6 to read the same , or very close.

Herm.

Re: Crankshaft Alignment to Block
 

Agree!

Herm.

Re: Crankshaft Alignment to Block
 

and the spec is for 9-12-3 to be within .006

Re: Crankshaft Alignment to Block
 

Those are my thoughts exactly...just finished experimenting with a round of shims and movement of the top tabs..the maximum correction I could obtain was less than 0.002 at 9 Oclock and 3 Oclock by shimming the tabs, all the way from no shims to a 0.020 differential between tabs. I was afraid to go a lot higher for fear of breaking off a tab. :-)