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Posted by: 72914S May 28 2007, 07:56 AM

Well I finally got all the pieces for the rebuild.Yesterday Joe(Redneck Racer) came over,we planed to check the deck height.We put the crank in(those bearing pins are hard to line up).The rear main seemed real tight,finally got the dowel pin right and the crank turns freely.For the mock up I put the other case half on and tighted it up,now the crank won`t turn at all.Joe thinks I need line boreing.Let me say that this engine spun the rear main and cooked # 3 piston.Anyone out there have any thoughts. Am I doing something wrong.

Posted by: Bleyseng May 28 2007, 10:16 AM

Check the clearances in each bearing with some plasticgauge and then report back!

Posted by: kwales May 28 2007, 11:30 AM

Bearing bores don't usually get smaller. My guess is the rear main where you spun the bearing. One of two things could have happened, the bore got larger (wear) , or the heat from the spinning bearing galled (spin weld) the aluminum bearing seat. If it galed, the amuminum filled up the tolerance between the outside of the bearing and the bearing seat. Yup, the clearance isnt much, but it can make a heck of a difference.

In this case, a picture of the spun bearing seat may explain much. I have a small flat honing stone that I lightly block or rub across the inner machined surfaces of the case to locate swelled areas near the bolt through holes. The high spots show up. You might use the same process to see if you have a high spot or ridge in the spun bearing seat. That would be your problem. If you do, blocking and sanding is NOT a solution, a proper align bore and oversize bearings are.

Ken

Posted by: McMark May 28 2007, 04:27 PM

Pull it apart and inspect the main bearings. Probably missed a dowel pin. Also check the cam bearings. the cam thrust bearing likes to spin unexpectedly.

Posted by: r_towle May 28 2007, 05:26 PM

I agree, and obviously you need to take it apart.

I do this, in this order.
Put in crank, no cam, no rod bearings, no rods.
Tighten case to spec, all the bolts.
Make sure the crank rotates with nothing attached.

Then I do the rods, same deal.
then I do the cam, windage tray etc.
Each time I check to feel the resistance of the crank, if it changes, I remove the parts I juse did, and hunt down the problem.

The height of the dowel pins on the crankshaft main bearings is a big issue if they are to long, they crush the bearing when torqued to spec.

The pins are to keep the bearing from moving, nothing else...so they do not need to press into the bearings.

Measure all the pins installed, and measure the depth of the hole in the bearings, if you have aftermarket pins, you might find something.

RIch

Posted by: McMark May 28 2007, 05:29 PM

Aren't the main bearings designed with a certain 'crush'? If so, repeated tightenings would result in loose bearings. Maybe not a problem, but if so it would make me slightly nervous. (and I mean slightly as in, very little)

Posted by: r_towle May 28 2007, 05:33 PM

Not that I know of, but Jake will know.
If that was the case, when you put in new (TO Spec) bearings, then the case halves would not meet, you would need to suck them in with the bolts, and I have never had to do that, unless the dowels are wrong.

Rich

Posted by: McMark May 28 2007, 05:37 PM

I'm definitely not talking about 0.125" of crush. Try more like 0.005". You wouldn't notice that 'gap'.

Posted by: r_towle May 28 2007, 05:57 PM

never bothered me..
But, I dont do as many as Jake, and all of the ones I have done have less that 50K...so...not sure...would be nice to know though..

Get the man to answer up...what is he doing?

Rich

Posted by: 72914S May 28 2007, 07:37 PM

The crank has been pro ground(20 over)& balanced.The new mains are 20 over inside standard outside.I quess I should confirm this,could have been bad packaging.

Posted by: Jake Raby May 28 2007, 07:38 PM

This case MUST have the main bores measured both with and without the main bearings in place as it sounds suspect for a case of main saddle collapse.. This can happen when a single bearing gets very hot and stays that way for a long while before failure. You can send us the case for eval and align bore if you want.

The big rule of thumb is that the engine must turn absolutely free when the shortblock is assembled.. It should take absolutely no more than 8 inch pounds of torque to rotate the engine with the shortblock totally torqued!

Some people think that engines that are new should be tighter at assembly time and that they'll free up as the engine gets some time on it...WRONG!!! If anything they'll have high oil temps and SEIZE in extreme cases!

It sounds to me like you may have "missed a pin" when you installed the crank.. IF you had my video I would have shown you the easy way to keep from doing this.... The video makes the assembly much faster and takes a lot of guesswork away.

Posted by: shaggy May 28 2007, 07:48 PM

the first time i put my 2056 together i missed a pin
the only way it would turn was to grab the impeller with gloves and put all my stregnth into turning it.

i changed it and reassembeled and then it turned with one hand like nothing at all.

id check the bearings. those are a bitch. jake's video does help even though it dosent mention tapping and plugging the oil gallies.

jake when does 'blow it up' premire?

Posted by: ptravnic May 28 2007, 08:06 PM

Posted by: 72914S May 29 2007, 06:20 AM

I have Jakes video quess I`ll watch it again.

Posted by: Joe Ricard May 29 2007, 06:48 AM

We pulled the pin and tried it that way, no difference. The outer diameter of the bearing DON"T FIT THE CASE.

I agree that the the case bearing saddle has collapsed. If you had seen the carnage of when Barry pulled the motor apart some of you may have gotten sick to your stomach.

What Barry really needs is for someone to hook him up with a good case.