The Guy in MY 99TA

I put the crank in the block yesterday and turned it over... everything was fine....... put the middle(#3) main cap in and run it down...... turned fine.... put the number 4 cap on turned it everything was fine....... put the number 2 cap on...... tightened it down some and the crank would BARELY turn...... it was hell to turn.

So I tried a set of bearings from another journal...... still the same...... tried a different main cap..... same problem

the crank has not been dropped or bumped in any way and I had it balanced and everything seemed to have cam out fine.... I call myself checking the straightness of the mains with a straight edge and feeler gauge.... and this is a new block right from SDPC

I was thinking if the crank was egg shaped(also a brand new eagle 4.00 stroke crank) on that journal that it would have been noticed during balancing.... but maybe not

What do you guys think?

Josh S.

Phil99vette

iTrader: (11)

Did you switch to main studs?
Phil

mmmchickenboy

it doesnt sound like a good idea to be switching caps and bearings... is the crank lubricated? do you have the correct size bearings?

Cstraub

iTrader: (1)

Crank journal has taper.

Ben R

It could be the housing bore is off, but it could also be the crank journal like Chris said. Check the crankshaft with a Micrometer to check for out-of-roundness. That will tell you if it's the block or the crank.

kossuth

iTrader: (12)

Has the block been line bored? That will cause what is going on here. Check and make sure. Also like others have said the crank could be out. If the crank checks out ok then it's obviously the block. Just because the block is new don't assume it is AOK.

Also, if you did add studs like the one person eluded to, you SHOULD HAVE it line bored. Aluminum can distort alittle differently with studs vs bolts, thus you could have the problem.

The Guy in MY 99TA

I forgot to add...... this is an iron block.... I assume the block had to have been line bored from the factory.

I am running main studs...... but I was using the factory bolts that came with the block just for some test fitting

I wasn't switching caps and bearings up permantely...... I was just thinking that somehow one set of bearings might have been thicker than another.... or one cap might have been a little defected.


its lubed with mobil 1 10w30 synthetic

all bearing numbers matched up

and the bearings seem to work fine in other mains....

I am gunna take it down the the local engine builder and have him check it out.... b/c I don't have a mic that big and I'm sure he has a dial bore gauge and a good straight edge to check the block with

ta40k

I think it is much simpler than any of that, I did the same thing building my iron block 408 at 4am trying to get it ready for a race weekend. Check the position of the main caps, that is the direction that they are facing. You would think that they would all go the same direction, but the front 4, ( numbered 1 - 4) go in with the ends pointing towards the rear of the block, and the rearmost cap (number 5) goes in with the ends pointing to the front of the block. Any one cap installed the wrong direction will make the crank damn near impossible to turn. After my groggy *** looked in the assembly manual, I realized my problem. Hope this helps.

NemeSS

iTrader: (127)

could be main cap is facing wrong way

Elite_Hot_Rod

If the block was line bored using bolts to retain the mains then you switched to studs that's probably your problem.

Jason99T/A

iTrader: (21)

Couple things to consider:

- Make sure the caps are facing the proper way as mention above.

- Check the housing bore diameters.

- Check crank for straightness. I have had Eagle cranks out the box that were bent and had to be straightened.

Cstraub

iTrader: (1)

New blocks most of the time need line boring. I would bet taper or runout on the crank. The main that is in question have the machinest measure the middle of the journal and the sides of the journal.

If you are putting studs in the block I would take it with you also. Have him torque the mains with the bolts and measure the housing bore. Then take the bolts out and put the studs in, torque, and re-measure to see if your numbers change. If they are within spec then your okay.

427

iTrader: (3)

Check clearance on the edge of the bearing to the radious in the corner of the crank. Take out the 3rd main and see if the crank will turn with #2 tight. You may need to run a narrowed bearing or chamfer yours on the edge.


Kurt

The Guy in MY 99TA

The crank doesn't turn with just the #2 cap down... i'm gunna go check to see if the caps are facing the right way right now ...... I don't really remember

kossuth

iTrader: (12)

GM made it fairly idiot proof by stamping the cap numbers into the caps. I just had the mains off my motor recently and the way GM does it if you are standing behind the motor stand facing the motor with the motor flipped upside down all the cap numbers should be on the right with the exception of the number 5 on my motor it was on the left side of the motor. Also the flat side of the cap should be facing the front of the motor except the number 5 cap which it's flat side faces the back of the motor. You know how the mains look like a C on one side and the other is perfectly flat, that's what I'm talking about. Doubtful you put it in wrong though, it just won't look right. If in doubt post pics and we can tell you if they are in right or not.

Randy WS6

iTrader: (69)

Why don't you try using plastic gauge that will tell you the oil clearance between the crank and bearing ,I purchased a brand new LS6 block a few years ago and had the same problem and checked the clearance and it was like .0008 . this must be a common problem because you can buy main bearings for the LS1-2-6 motors that are +.001 under size, after installing the under size bearing my clearance was .0018 and loosened the motor right up .like i said my stock crank was locked up in thenew block ,The line bore in the new LS6 block was just to tight .The motor is running perfectly over 2-1/2 years now and cranked over 7600 rpm miny miny times .The bearing are a lot cheaper than a line bore job unless the clearances are uneven across the five caps .I got my bearings from Thunder Racing there on there web sight>>>>>>

DaddySS

Remember the caps do not attain their correct shape until they are torqued to spec. If you tightened it "some", that's not good enough, torque them fully and then check it.