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Old 12-27-2008, 11:38 AM   #1
coony278
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Default SBC thrust bearing problems

I'am assembling a 383 engine. The engine has a fresh line hone done.

When I put the crank in and torque down the rear main cap the engine locked up. Checked the end play with the cap torqued and it has none.

With all the other caps torqued down and the rear cap removed the engine turns perfect. And has 6 thousandths end play.

My machinist said this was common and to sand the thrust side of the bearing until cleances was correct.

I did this and the engine turns freely and has proper end play now.

Now I trust my machinist but this just seems wrong to me.

What would you guys do ? I'am thinking about returning the block to the machine shop that lined honed it. My machine shop does not line hone. I had BB&T in memphis line hone it and I believe them to be a good machine shop.

Any input would be appreciated.
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Old 12-27-2008, 12:19 PM   #2
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Quote:
Originally Posted by coony278 View Post
I'am assembling a 383 engine. The engine has a fresh line hone done.

When I put the crank in and torque down the rear main cap the engine locked up. Checked the end play with the cap torqued and it has none.

With all the other caps torqued down and the rear cap removed the engine turns perfect. And has 6 thousandths end play.

My machinist said this was common and to sand the thrust side of the bearing until cleances was correct.

I did this and the engine turns freely and has proper end play now.

Now I trust my machinist but this just seems wrong to me.

What would you guys do ? I'am thinking about returning the block to the machine shop that lined honed it. My machine shop does not line hone. I had BB&T in memphis line hone it and I believe them to be a good machine shop.

Any input would be appreciated.
Make sure you have the correct size rear main bearings!!!!

See if the front or the rear of the main caps has been cut as one side of the cap has to be squared to the bottom of the cap so it can be cut square.

Make sure its the right cap and if there is a dowel pin for aligment remove it and set your own thrust clearance like what you would do on the late 350 blocks.

I should be around today give me a call 207-892-7215
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Old 12-27-2008, 09:48 PM   #3
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I'll give you call monday. Thanks
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Old 12-29-2008, 09:04 AM   #4
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Did you set thrust? My favorite part of assembly! torque them all, loosen up the rear cap 1/4-1/2 turn until you feel the pressure release but the cap is still not flopping around. give the front of the crank a good whang with a rubber mallet. Same to the rear if possible. If you can't hit the rear (no pun intended) wedge a screwdriver between one of the main caps and a counterweight forcing the crank forward as you tighten up the rear cap. That should align the rear faces the of the thrust flange and loosen up the crank.
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Old 12-29-2008, 02:31 PM   #5
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Quote:
Originally Posted by coony278 View Post
I'am assembling a 383 engine. The engine has a fresh line hone done.

When I put the crank in and torque down the rear main cap the engine locked up. Checked the end play with the cap torqued and it has none.

With all the other caps torqued down and the rear cap removed the engine turns perfect. And has 6 thousandths end play.

My machinist said this was common and to sand the thrust side of the bearing until cleances was correct.

I did this and the engine turns freely and has proper end play now.

Now I trust my machinist but this just seems wrong to me.

What would you guys do ? I'am thinking about returning the block to the machine shop that lined honed it. My machine shop does not line hone. I had BB&T in memphis line hone it and I believe them to be a good machine shop.

Any input would be appreciated.
had to do the same thing to gain a few thou clearance, my machinist and engine builder both do it this way (both good and respected in the area), motor had been down the track about a 100 times, apon inspection, everything is perfect, end play is still .007 as set
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Old 12-29-2008, 08:36 PM   #6
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Thanks for the help guys. I called BB&T today and they also gave me the same answer as everyone else.

Looks like my engine is ready to run , just need some good weather now !!! It wont be long.
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