Has anyone actually used a thread chaser prior to installing studs? And which one is required for the 4.0 block.

7/16" - 14?

ARP Kit number 911-0004?

 

The bolts are 7/16-14. When I did the heads on my truck I took an old bolt and cleaned the threads up with brake cleaner then threaded them into each hole to check and see if they were clean. Every one went in with zero effort so I skipped the thread chaser. If you can seem to get them looking spotless with brake cleaner then you might need to use a chaser. Make sure there is no oil in the threads in the block if you are using the ARP studs. I went with stretch bolts as I believe they are a better match for aluminum heads and blocks but studs are meant to stay in one place in the block so don't oil them.

 

I used the old bolts and had one misfit. used a tap on that one...because I had one on hand, in that size.

 

you should use a thread chaser or a 7/16 x 14 bottoming tap

 

I would say ideally you should use a thread chaser, especially for tty bolts as their installation requires an initial torque followed by rotation within the threads and both of these actions are impacted by crap within the threads. However, for studs you will be installing them in the holes initially then the torque is purely a function of the nuts rotating on the threads on the studs so it isn't as critical.


The machinist that did my cylinder heads told me that a tap should never be used as it can cut a little more material which is the last thing you want for these blocks. A thread chaser is slightly smaller in diameter than a tap and has a different angle on the leading edge to make sure that it doesn't remove any of the threads, only restores them. For my block, the holes were mostly spotless so I didn't take it any further but had I needed to, I was going to grind two relief slots up the sides of one of the used head bolts to act as a chaser. On one of the holes, I had to use a dental pick I had to scrape out a little bit of stuff but that was it.

 

I am going studs.
For 30+ bucks I'm skipping the thread chaser I'll just have to make sure the thread holes are completely clean,clear, and dry. I'll make it work. Thanks guys.

 

When I did my heads, I was gojng to get a bottoming tap to chase the threads. Then I read that you shouldn't because the tap will cut some material off the threads and loosen the fit. I ended up getting loaner thread chaser kit from Autozone.