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Main cap thread repair inquiry (Gen 3 Mopar)

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Just got my rotating assembly back from the machine shop making it the last planned item to have machined before engine assembly.

(This engine will go back into my cruiser Dodge Magnum R/T which I refuse to let die.)

Tonight I started assembling after checking all of my gaps/ measurements, etc. And upon torquing the main caps I stripped a thread .

This is only my 3rd engine rebuild, and I've not had this happen before.

My goal is to have a strong reliable cruiser for another 120k plus miles (~200k km).

Hoping for some input from someone who's had good experience in this type of repair to chime in, or what the standard repair for this is/should be; as I'm not sure what my options are aside from a helicoil/threadcert.

If so, is it something I should even attempt to do myself (unlikely), and if I do one, should I do them all?

Once I do, should I move over to studs?

I'm already in the block for all of the machine work, so if it's salvageable I want to keep it.

This is likely caused by my improper thread chasing btw, so I'm assuming the other threads, even though they torqued out, are not for from failure as well.

Definitely a learning moment for me.

Attached Files

Not quite sure how you managed that, 'cept maybe using the wrong thread pitch, but that's neither here nor there.

The problem now is a/ how to repair that thead, and b/ will the others also need to be repaired - I don't think I'd take the risk and re-work them all, if I went that route.

You REALLY need to speak to a specialist in these types of repair, because the only options I can see are either use oversized/stepped studs or have inserts fitted into the block. Either option is going to be $$$ and you're going to have to get a specialist's estimate, or quote, to get the work done, and any other work that may need to be done at the same time. Then do some hard thinking about that total repair cost Vs writing off the current block* and picking up another and re-doing all the machining.

There are machine shops that specialise in Chrysler engines, can't recommend one, but thay may be able to advise you.

*If you're determined to keep the car, you may also need to consider how important "matching numbers" are to you!

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