Just like the title says, and it's causing the actual bolts to strip stock and arp bolts.
I would not like to have to trash a good running motor if I don't have to (d16y7). Maybe some sort of tap?

 

Have you tried chasing the holes with a M12x1.0 tap?

 

I recently had to do this on my car. worked perfectly. slapped all new oem bolts in after and called it a day, zero issues since

 

Please make sure you know how to chase threads before doing this. If you just run a tap through you will just create more of a problem if you don't do it right.

Also, be very careful, if you somehow break that tap (I doubt you will, but accidents happen) you can mostly kiss that crankshaft bye bye.

 

Thanks for the info, I'm un familiar with the term chase it's been since high school since I've used a tap, use a chaser or tap?

 

Use a tap as a chaser.

 

Chase = clean up the damaged threads in the hole or holes of the crankshaft. Order a M12x1.0 (extra fine) pitch tap. Use a lubricant like WD-40 on the threads and insert the tap. Turn into the hole until it gets difficult, then back off, clean out the hole with brake clean, re lubricate and re insert into the hole. Repeat until the entire hole is clean. To minimize the risk of breaking the tap off in the crank, only twist 1/2 to one full turn clockwise with the tap when it is hard to turn... remove, clean and re lubricate.

 

a tap is designed for cutting new threads, and they often are not made to strict tolerances. which means most taps actually cut the threads a little too large.

a chaser is like a tap, but is made to much much stricter tolerances and is specifically designed for chasing damaged threads, not cutting new threads.

you can use a standard tap to chase threads, but be warned it can make the bolt a bit sloppy in the hole if its a low quality tap. standard hardware store taps are most common for this issue. unfortunately high quality taps/chasers can cost up to ten times as much as standard taps.

 

this was my first thought. the "right" tool for the job, a good quality plug tap will cost as much or more than a good used crank...

 

Buy a decent used 6H BOTTOMING tap off ebay. If you find a spiral flute, spring for that one as it will pull crud from the threads just like a drill bit.

You can probably find a nice OSG for less than $20.

 

I went to Tacoma screw and picked up a tap I probaly spent 30$ in all and cleaned the threads multiple times as instructed above and seemed to work was able to get the bolts torqued down with thread locker

 

Great! Glad it worked out for you.