Scat crank issues

[mike7570]

I believe I avoided a major problem with my engine assembly getting it ready to drop in the car. I was installing the flexplate to check starter engagement and I was starting the 6 ARP bolts finger tight. The last bolt was a little snug but went in a couple of turns with just my fingers. It felt like the bolt was dragging a little on the flex plate hole (they are a tight fit and the flex plate only goes on one way) the other 5 seated easily with a little ARP lube under the head and some loctite on the threads. The snug bolt I put the wrench on and gave it a turn, oh oh it feels too tight. I reversed the wrench to back it out and it got tighter and tighter coming back out. Finally had to use a breaker bar to get it out, the bolt was toast and the first 1/4 of the threads in the crank looked messed up.
I bought a new bolt and ran a tap through the crank and it looks like 3/4 of the hole threads are good and the new bolt tightened down to torque without any problems.
Do you think engaging 3/4 of the threads on one of the six bolts could be a problem? I have had 2 oem steel cranks and the threads were never a problem they seemed pretty robust. The Scat threads almost looked helicoiled from the manufacturer, they don’t look well defined. I did run the tap through all of them and made sure I fingered tightened enough to know it was threaded correctly.

[Katz427]

All I can say is "text book" rule is 1 1/2 times thread diameter, gives the threaded hole depth for optimum  strength, holding, torque.

[70tp]

I feel that if you were to run the bolt in there and it will torque to spec, then I wouldn’t hesitate to run it as is, if it won’t hold then helicoil it and run with it

[MeanGene]

If one keeps getting tighter, stop and let it cool off for a while- tight threads generate heat that makes them even tighter

[mike7570]

It was odd, the bolts are 7/16-20 and I twisted it in with my fingers. It really wasn’t that tight. I knew not to keep tightening with a wrench if it wasn’t turning easily. It must have jumped a thread on the way back out because that’s when it really tightened down. I inspected the bolts before using them my mistake was not running a tap through the Scat threads. I wasn’t impressed with the quality of the threads compared to my forged steel cranks. The scat cranks are “cast” ?
I feel lucky the tap was able to align to the original threads and not cut new ones. Only the first 3 or 4 threads were damaged and while the tap straightened them out they’re probably a bit weak. The rest of them are fine and I was looking for a few opinions to put my mind at ease, thanks