Building a sbc 400 one of the main caps do not line up correctly, what do I do

ANDREW72400

MEMBER
1990 CHEVROLET TRUCK

I am building an sbc 400 the 3rd main cap from the front will not go into place as the other ones do. It fits backwards, there is about a 16th of an inch till it falls into place. What do I do? The motor was running when pulled

Saturday, June 2nd, 2012 AT 10:17 PM

5 Replies

HMAC300

MECHANIC
48,601 POSTS

Are you sure you didn't switch them by mistake? About the only thing you can do is to have it line bored or have someone that knows small blocks andmkae sure it's in correctly. Or if this is a used motor maybe someone else put the wrong cap in and put it backwards. The tangs on the bearings shold be on the same side, if they are then it's correct.

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Saturday, June 2nd, 2012 AT 10:43 PM

ANDREW72400

MEMBER
3 POSTS

This motor was never taking apart till I got it. Caps are on right spot. One the one main when on backwars (arrow pointing back) the tangs on bearing are lined up when cap it turned around. I think it was put on wrong from factory but it was a good motor with 345k I got from original owner
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Saturday, June 2nd, 2012 AT 11:00 PM

HMAC300

MECHANIC
48,601 POSTS

As long as the tangs line up and crank turns easily it should be ok then

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Saturday, June 2nd, 2012 AT 11:02 PM

ANDREW72400

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3 POSTS

DO YOU KNOW IF GM DID SCREW UPS LIKE THAT?Its never been apart and I have build hundreds of small blocks and never seen that.

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Saturday, June 2nd, 2012 AT 11:37 PM

HMAC300

MECHANIC
48,601 POSTS

Small blocks came form 2 different plants, I have seen many screwups to mention. It may have been a block that was resent through the line because of something similar to that.