When I was a pro wrencher, we always replaced TTY (aluminum head) bolts. Iron heads were not TTY and therefore were reused. There is a different torque spec for used bolts. That said, I was opening up engines for the first time.... that had a decently known history. That engine may have been apart 1,2,3 times by now. Those bolts may have been torqued several times (unless you know otherwise) I would buy new ones. Studs are for high HP high compression stuff like HIPO or modern diesel. I'd go decent aftermarket or OEM if they are available. ARP are of course the safest bet, but the mo$t cash.
"Taps" cut threads , "thread chasers" clean threads , if you're using a tap your damaging the threads
I have collected taps and dies for years, garage sales flea markets, etc. Everytime I see a pile for cheap it goes in to my tap drawer. One of the things I do to prep a block is to “ chase” all the threads in that block, especially the heads and mains. I usually just grab the bottoming tap of the right size and run it in and out. I have never seen any “ metal “ come out of any block! Rust, dirt, crud, maybe but no shavings. I have been doing this for years. Most of the time I’m turning the tap wrench with my finger, spinning it into the hole and back out. Now you are telling me , I’m cutting new threads doing this? Bones
I always had two thread chasers, 3/8th and 7/16th. After spending two days looking for them, I said screw it. My last Summit order I bought a set of metric and SAE. I think they were only 12-15 bucks a set.
Over the years, I have collected problaly 2/300 taps and dies. I have a few semi complete sets. And have purchased a few new taps, mainly for cutting aluminum. But with the new off shore stuff coming and good old American made stuff becoming scarce, I guess I will have to just stay with the ones I got. I had the good luck of finding a stach of pipe taps years ago and got a whole set from 1 inch to 2 1/2 inch for cheap. I used them a bunch in my career! By the way, I use that multimeter the other day! Works great.... again , thanks! Bones
True all threads have several differant classes.Depending on what class of thread the tap is made for will determine the fit of the bolt.I agree a thread chaser instead of a tap should be used.I used a tap on a banger block i rebuilt and wished i had not.The head bolt threads were much looser than the original tapped holes even with new head bolts installed.
Some taps are marked +.001, +.002 and so forth.... Some are also marked undersize -.001 er -.002 for a tight fit... It's best to buy quality brand name taps for tapping or cleaning threads instead of those cheap Chinese ones...
The Jalopy Journal
