I am rebuilding a S.B. chev 350 4-bolt Block No.207 1984 vintage i think.
Problem i have is that i have just installed the stock crank (micro polished) with .001" undersize F.Mogal bearings.
when i installed the rear main to 70 ft/lb the crank spun good but when i put No.3 cap on at 30 ft/lb it locked up solid....
Not to sure wat the problem is???
Only 2 caps have (2) and (3) stamped on them.
Arrows are to front.

You may have some mis matched caps if you have someone bore gauge them for you to find out where the problem lies.

At our shop when we prepare a block for a customer we line hone every block to make sure nothing happens like this amd it takes the guess work out.

Just making sure... you did use lube on the crank, right? I know it is an elementary question, but you didn't mention it. It sounds like maybe your bearings are mis-sized or the machine shop bozoed the crank.

I have had the same problem before, i basically had to play musical caps until i got the combination right.

I always stamp the caps and rods before I remove them for exactly the reason you describe. It's easy to mix them up.

Some people stamp them with numbers, others just use a series of little dots, especially on the main caps.

. (1)
.. (2)
... (3)
.... (4)

So look around.

If a professional tore the motor down without marking everything he's a dumbass. If you tore it down, don't feel too bad- beleive me, everyone forgets once. But rarely more than once. I had my one instance of forgetting many years ago.

plasti-gage the suspect bearing caps if you have to- see what's going on.

Thanks guys... being an engineer i will mic the mains and measure shells and crank to see where its binding...will try plastigage too...

My old boss used to say "The only people who don't make mistakes are the people who aren't doing anything";-)

That's the truth! At Motorola we had a saying, "Do something, even if it is wrong".

<font face="Arial,Verdana" size="2">Originally posted by Damon:
If you tore it down, don't feel too bad- beleive me, everyone forgets once. But rarely more than once. I had my one instance of forgetting many years ago.</font>

i can relate to that http://www.nastyz28.com/ubb/smile.gif

The mic will not lie, good place to start.

Also you are useing the proper torque pattern starting off with a 30% or so of the recommended final spec and working up to it in three stages on all the caps in proper sequence per the book right?

Not trying to be a wise A$$, just making sure...

I remember one time I had a main bearing set that had one wrong size insert in it- I think it was a .020 undersize set that had one .030 shell in it (factory defect). The parts store didn't blink an eye, they just gave me another set or replaced the insert, my choice if I remember right.

You prolly checked this, but I must have had my head in a really stinky place that day because it didn't dawn on me until I miked them and then saw the markings.

i had the exact same problem, i took off all my caps and marked them so i would have a starting point and then i started switching them around till i got it to spinn free. it will take a while but you will figure it out eventually.

You can do this the quick, "shade-tree", way by removing everything and then installing all the mains to about 25 pound T.

Then use your fingernail to "FEEL" the parting lines. I say this b/c your fingernail should be able to detect .0002" difference in dimensions!!

Then start from there to start measuring properly.

I always sneak up on my crank torque process by doing it in steps while spinning it. If it locks up, I then know I have a problem and so I look closer.

Hope it's nothing for you b/c stuff like this CAN really become a big pain!!

pdq67