4.2 main bearing bolt

[knife51]

I have a AMC 258 i6 / 4.2l that had a oil leak, pulled the oil pan and found one of the main bearing bolts broke laying in the bottom of the pan. no problem i got an old block i will just get one of those. The bolt will not fit it is a 1/2-13 bolt the one that broke is 7/16-14. Checked everywhere trying to find main bearing bolt of that size no luck.I know the motor is a AMC 258 i6 / 4.2l because the number on the block has the letter c in the number. What gives?

 

[Patrick]

Match it with an ARP bolt and replace both main bearing cap bolts. Be glad you caught the issue before a catastrophe.

 

[knife51]

Tried that no luck. Found a head bolt of that size used that. Trying to figure out why this block has 7/16 bolt size instead of 1/2.

 

[Patrick]

Right on

 

[yellow85cj]

Can't remember which is which, but early years used 7/16" and late years used 1/2". Could be the other way around.

 

[knife51]

The engine code is 011c27 don't know if the zero is 80 or 90 thanks for the replies.

The engine is a remanufacture. Don't know what it came out of.