Packard Forum Index » Pre-War (1899-1942)

Quote:Tom,

Think you'll find that when the crank is tightened to spec that it will turn. With the caps partially tightened everything is "slightly" out of line and fully tightening the caps brings everything back into proper alignment. Wade found this out when doing his '37 Super 8, and I know it's not a babbit bearing engine like your '34. It's amazing that tightening everything up actually frees up the crankshaft so it can turn, not spin mind you.

Tread Cautously! Since the caps wer not tightened down i am very suspicous that the line boring was not completed.
It strikes me as odd that a shop would line bore WITH A CRANK PRESENT and not go ahead and button it up by torquing the caps THUS COMPLETING the operation which is usual, customary and EXPECTED .

Follow Owens advice on the measureing with micrometers FIRST.

U need to find someone that knows what they are doing with fitting cranks and bearings. Not someone that has read Hot ROd magazine or took some Auto Certification course at a local tech college. Based on what u've listed thus far i can only wish u GOODLUCK and prayers!!!

Thanks all. We are going to do the measuring, etc. tomorrow. I will hopefully be back with good news.

NOTE that ONE of the bearings in the block is special in that it takes the fore and aft end thrust of the crank. Check the clearence/finish of bearing thrust face there too. If it is too tite that can create crank fit probelms.

Turn the block upsidedown. Place a lite coat of engine oil on each bearing and the crank main journals. Place crank in block WITHOUT caps.
Inspect each bearing-to-crank fit by eye to see if the crank is setting all of the way down into the bearings.

SLOWLY and cautously at first try to turn the crank. Does it turn freely????

Next, use some PLASTIGAUGE (it's CHEAP and effective).

Follow generaly accepted Plastigauge procedures/instructions which are available probably by googling "Plastigauge" or reading just about any service manual.

Some additions comments:

If possible find out if the mains in the crankcase were line bored while it was bolted to the block.

To do the line boring operation correctly the crankcase must be bolted securely to the block. If it is not, there is a good chance the alignment of the mains will not be on the same axis when it is attached to the block. End result, a tight crank and improper or non-existent oil film, which will destroy the babbitt bearings quickly.

Tightening the crankcase to the block will distort the crankcase slightly, this is why it must be bored with the block attached.

I've seen work where the crankcase was line bored without the block attached and the engine re-builder attempted to correct a tight crank by selective tightening of the block to crankcase nuts, trying to bow the crankcase to correct improper main bearing alignment.

If the line boring operation was performed with the block attached I would attach the block securely to the crankcase before checking clearance in the mains with Plastigauge.

If the crankshaft has been stored horizontal for two years, check it for straightness before you check clearance in the mains. You should always store a crankshaft vertical, if it is stored horizontal for a length of time it could have bowed.

Regards,

Dave

Quote:

No, the line boring was not done with the block attached. Another bit learned. Another bit learned to late .

Quote:

The crank was stored in the crankcase. I left everything as it was shipped from the machine shop.

I'd still get the micrometers out and check everything, including as already suggested the crank end-play thrust surfaces. If all checks out OK, get out the prussian blue indicator and find the high spots. If it's just one small edge that's high because perhaps of not line-boring attached to the block, you might get away with a little babbitt scraping as the old-timer bearing fitters did.

Dear All,

Thanks again for all your help. I now have a new question. I know the minimum clearance for main bearing to crank journal is a thou, but what is the maximum clearance recommended?

After the cylinder block was attached to the crankcase, and many measurements were taken, it looks like the main to crank clearance is from 0.0015 to 0.0029.

I am sure that this information is someplace in the service manual, but I am, so far, at a loss as to where.

As always, any help is much appreciated.

Thanks,

Tom

I didn't locate the range for your particular year and engine, but in later years one source (Motor's) gave the range of acceptable clearance as 0.001 to 0.003 for the 320 engine and I can't think of any reason why yours should be different.