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Main Bearing Cap Installation


HuD 91gt

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I finally got my block back form the machinist.  It's painted, core plugs installed and ready to go back together.

 

Having never done any work like this before, i'm having an issues installing the main bearing caps.  The How to book's don't give a great description on how this is done and I am afraid of doing damage using any sort of force.  The tolerances seem very tight.

The how to book's recommend first filing any burrs on the edges of the caps (I've yet to do so).  I've tried lightly tapping them in place with a rubber mallet.  Should I place some old rod bolts in, to line the caps up, then tap?   Freeze the caps? Should they be oiled first?  If someone could list their steps for installation that would be great.   It's probably very simple, but i'd rather be cautious rather then buggering it up.

My head will be complete from Whitehead performance on Thursday, and i'd like to get this bottom end back together.

 

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They're a tight fit for sure, some oil or assembly lube wouldn't hurt on the sides if they're that tight.  I used a rubber hammer on mine, about half way the bolts will catch some threads and you can pull them down with the bolts.  I ran the bottoms of mine across a file.  Make sure the numbers are in order and the arrows point to the front.  The middle one and the rear are the tough, or anxious ones for me.  I learned a trick from Dizeased on the rear, stop about an inch short of bottoming out and insert the "nails".  Push them all the way down then tighten the rear cap down.  It's nerve wracking as hell to me too so don't second guess yourself too much. :)

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Have you let the temperatures even out?  A cap straight from your warm clammy hands might be a little bit bigger than the cold slot it's going in to.  Taking it a little further, some time in the refrigerator might help, although visions of a half-inserted, jammed cap come to mind.

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The cap is in the same cool garage (8-10 degree Celsius, or guessing about 48-50 for y'all Southerners) as the block.   Temperatures would be the same (If not very very similar).  My issue seems to be lining the cap up, before tapping it with a hammer.   If it's not perfect it's obviously going to go one way or the other....  The both of those options are not into it's recession!

I read an idea to put the caps in the freezer first.  It's funny though, you can search this question on all the forums and nothing really shows up.  I think I must be putting it upside down or something else ridiculous (Joking obviously).  I'd feel much more comfortable tapping the caps in, if the edges were bevelled.   Straight sharp edges, and force just makes me cringe of creating sharper edges in tight tolerences that are supposed to be as smooth as a couple babies bottoms.

Edited by HuD 91gt
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I should also note, they were actually quite difficult to remove, which is why i'm so cautious about putting them in.   If it takes half the force to put it, as it did to knock them out, it would be easy to damage some metal.   Maybe all I need is a warmer garage?  Or a heat gun.

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