Overtightened/torqued main cap bolt

[Mac2Night]

So like an idiot in a hurry, I overtightened/torqued (1) main cap bolt. It's a newly rebuilt motor and everything is new so I'm tweaking about snugging this one bolt (not the whole cap, just one side with the stud to hold the oil pick in place). What should I do, loosen and retighten to spec or leave as is? I'm concerned I might break the bolt or by loosening it then it will misshape the bearing even more (if it is messed up already). Like I said, I may just be overthinking it but I want to ask.

Thanks guys!
Mac

 

[73azbronco]

"Should" be OK, just loosen and retorque. But, I'd look close at seam of the two bearing halves make sure that is not mushroomed. It should not be hurt.

Are you using plastigage?

 

[Mac2Night]

I just had the motor rebuilt and didn't do the work myself but professionally done. I DO NOT want to take the whole cap off if I can keep from it as I have no clue what to look for or gauge. I also don't want to break bolt off in block by loosening it if I damaged/stretched it over torquing it to begin with.

Is there a way to tell by turning the motor by hand?

"Should" be OK, just loosen and retorque. But, I'd look close at seam of the two bearing halves make sure that is not mushroomed. It should not be hurt.

Are you using plastigage?

 

[markatherton]

torque

Loosen and retorque

 

[hankjr]

how much did you over torque by?

Hank

 

[Mac2Night]

A lot I am thinking. Because I didn't put motor together, I didn't check specs before dealing with this bolt. I more likely really did over tighten by 30-40%. Remember, I didn't remove the cap, just one bolt on one side of the cap.

how much did you over torque by?

Hank

 

[Viperwolf1]

I just had the motor rebuilt and didn't do the work myself but professionally done. I DO NOT want to take the whole cap off if I can keep from it as I have no clue what to look for or gauge. I also don't want to break bolt off in block by loosening it if I damaged/stretched it over torquing it to begin with.



Is there a way to tell by turning the motor by hand?

If it breaks when you loosen it you probably didn't want to leave it in there anyway. Take it out and inspect the threads. Replace the bolt if possible. You probably didn't over torque by much or it would have broke already. The cap and bearing would be fine. The cap can take a lot more pressure than you can apply with a 1/2" bolt.

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[Apogee]

If it breaks when you loosen it you probably didn't want to leave it in there anyway. Take it out and inspect the threads. Replace the bolt if possible. You probably didn't over torque by much or it would have broke already. The cap and bearing would be fine. The cap can take a lot more pressure than you can apply with a 1/2" bolt.

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X2...better to break it now than later inside the engine and much cheaper to fix now too. Spec on a 302 is 70 ft-lb if I'm not mistaken.

 

[bulletpruf]

If it breaks when you loosen it you probably didn't want to leave it in there anyway. Take it out and inspect the threads. Replace the bolt if possible. You probably didn't over torque by much or it would have broke already. The cap and bearing would be fine. The cap can take a lot more pressure than you can apply with a 1/2" bolt.

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This ^^^

When I'm building a motor, I generally turn it over after installing the main caps and again after installing a rod and piston, camshaft and lifters, etc. That way if something is jacked up, I notice it right away. You can even use a torque wrench to measure how much torque it takes to turn the engine over, but that's really not necessary. If something is binding, you'll feel it.

You could still rotate this one if you wanted to. If the balancer is installed, just remove the spark plugs and rotate by hand. It shouldn't bind up once you get it moving.

 

[Rustytruck]

Loosen both bolts for that cap and alternate side by side in at least 3 steps until you get to full spec. the bolt will be fine if the threads were any good to begin with. then with the plugs out turn the crank with a ratchet and socket on the damper bolt you should be able to turn it. it will be snug and take a fair bit of force about the strength of an 8 year old.

 

[DirtDonk]

You said you overtorqued one only, but did you torque the other one at all? Was this just the first one and you installed the stud only, or are the others installed and you were doing the alternating torque sequence by the book?

If just the stud, I'd put the other bolt in and tighten it down at least a bit before you remove the stud/bolt. But remove it I would, just as the others have stated. You can leave the cap in place if you want, but I don't even see a problem with remove the cap if you have to. People do it all the time and simply re-new the torque sequence.

You can even tap the cap with a hammer (rap is probably the better term) to ensure even fitment before you torque it to spec.

Paul

 

[Mac2Night]

Thanks guys. I tried to turn the motor by hand just as it was (bolt still overtightened) just to see if it would turn. Really snug to say the least. Took Rusty’s advice and reinstalled bolts on that cap and tried again. Much better to say the least. I didn’t really move the motor when I first tried it so I’m hoping there isn’t any damage but I don’t know how I’ll know until it is back in the truck. Thoughts to hopefully put my mind at ease????

Loosen both bolts for that cap and alternate side by side in at least 3 steps until you get to full spec. the bolt will be fine if the threads were any good to begin with. then with the plugs out turn the crank with a ratchet and socket on the damper bolt you should be able to turn it. it will be snug and take a fair bit of force about the strength of an 8 year old.

 

[73azbronco]

So you are not checking bearing clearance then, just putting it together?

 

[Pa PITT]

I'd say If the bolt didn't break then I'd leave it alone . Now yes I would put a bar on the end of the crank & Make sure it turns. But Then I spin the crank aft each pair of bolt are tightened .

 

[Apogee]

If it were mine, I'd get some plastigauge and do a quick check on that bearing, just to make sure there won't be issues moving forward...it's something like $10 on Amazon.

 

[71 CA Bronco]

If it were mine, I'd get some plastigauge and do a quick check on that bearing, just to make sure there won't be issues moving forward...it's something like $10 on Amazon.

Times three. Very cheap insurance. You don't want to be dealing with it after its been put back in the Bronco.

 

[Steve83]

Loosen and retorque

^^^ This. ^^^

If the bolt will reach the specified torque, then it's doing its job & isn't about to fracture. If the torque rises & then holds low of the spec, the bolt is stretched & continuing to stretch (about to break, so remove it before you break it). It couldn't have damaged the bearing or crank, no matter how much you turned the crank by hand.