Crankshaft Alignment to Block

[tennsmith]

Originally Posted by tbirdtbird

"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

Hope I don't appear to be stubborn or naive, but I can't achieve more than 0.002" movement in the 9 and 3 positions with as much as a 0.020" differential between the upper tabs. I am afraid to go any higher for fear of breaking off a tab. Best setup I obtained was .007 low at 3 Oclock and .006 high at 9 Oclock and that was with NO shims on the driver's side, resulting in 0.011" closure from the "no shim" position and 0.013 shim on the passenger side. Any additional shimming of the passenger side began to increase the .007 low number to an even larger negative value.

In my simple mind, if I have 0.010" runout at the 10" semi-circle where the housing bolts to the block and I extend that runout to the 15" diameter of the flywheel housing, and my flywheel housing is "perfect" between the two faces, that's 0.015" I'm trying to correct and the best I can achieve is 0.013". I can't go past "no shims" on the driver's side to try and pull down the high side measurement and increasing shims on the passenger side, over 0.013 begins to worsen the measurement.

[Terry Burtz, Calif]

Robert,
I suspect that you have a bad align bore job.
In your first post, you said that when the dial indicator base was on the crankshaft flange and the indicator swept the machined surface at the rear of the block 180 degrees, the run out was .010 in. This is an indication that your crankshaft is not parallel to the camshaft. Remove the crank and cam shafts and measure the distance between crank and cam bearings at the front and rear of the cylinder block.
This problem cannot be fixed by shimming the flywheel housing.

[tbirdtbird]

This is possible.
I would repeat that measurement.
Also possible is that the bore is aligned properly but the flange is not true

[Kohnke Rebabbitting]

Originally Posted by Tom Wesenberg

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.

Tom and Mr. Thunderbird have it right Exactly.

Herm.

[Kohnke Rebabbitting]

Originally Posted by tennsmith

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. :-)

Do Not do any prying on either tab, Mr. as Thunderbird said, you do that in between them.

Guys, this always works, it is in you minds where were having trouble, but after you do it, it will become clear.

Herm.

[tennsmith]

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Originally Posted by Terry Burtz, Calif

Robert,
I suspect that you have a bad align bore job.
In your first post, you said that when the dial indicator base was on the crankshaft flange and the indicator swept the machined surface at the rear of the block 180 degrees, the run out was .010 in. This is an indication that your crankshaft is not parallel to the camshaft. Remove the crank and cam shafts and measure the distance between crank and cam bearings at the front and rear of the cylinder block.
This problem cannot be fixed by shimming the flywheel housing.

I have about reached that same conclusion Terry...no amount of shimming or differential between shims will come anywhere close to fixing the problem.

[tennsmith]

Epitaph......Many thanks to all for your suggestions and advice. I was totally unsuccessful with ANY shim combination or differential between shim stacks in getting the measurements any closer than a 0.013 spread. So this morning, I bolted the flywheel housing to a 1" thick slab of aluminum plate and milled it starting at zero on the passenger side and cutting across to the driver's side where 0.005 was removed, with 0.0025 removed at the 12 O clock position between the tabs. Remounted the housing, and made a quick check of the 3 and 9 position and they were within .005. Played a bit with shims and wound up with 0 at 12 oclock, 0 at 3 oclock, .003 at 6 oclock, and .004 at 9. That I can easily live with and the only downside is that if/when the crank is ever straightened in the block with a new babbitt pour, I'll probably have to go back and take .005 off the passenger side of the housing to once again true its front and back faces. I believe my inability to correct the misalignment was the fact that I had the most disparity between readings at the 3 and 9 positions, some .015" total, right where it was bolted to the back of the block....

[Fred A]

Poor alignment of the crank causes problems at the front of the engine also. Last winter I tried to complete a cash and carry short block, picked up at Turlock from a big name in engine building. Short story is that the line boring of the mains was off (too close to the cam) by a few thousandths. turning it over caused the fiber timing gear to fail. I tried another standard gear and was unable to get it in, too tight. My point is that Dan McEachern was able to supply me with an undersize timing gear that solved the problem. Now I'm soon to address the possible problem of aligning the trans to the crank and the thread has been useful. I had not before heard of an undersize gear but feel lucky that it was available. Good Luck: Fred A

[tbirdtbird]

Tennsmith if you ever sell the car I am sure you will advise the new owner of what has been done to the FW housing, since no one would ever figure this out