I had a discussion with JM late this afternoon, Matt. The 9/16" x 1/2 " Step studs John offers are approximately 7 inches long, which makes them approximately two inches shorter than an OEM stud. The shorter stud and higher anchoring point were chosen because drilling, reaming, and tapping at the original stud length/depth were difficult to do correctly, and even when done correctly, it was too time-consuming to make this a viable repair methodology. The shorter stud anchoring higher in the cylinder bank was the compromise solution.
When you anchor the head stud higher in the cylinder bank, the cylinders distort when the studs are tightened to their torque specs. The distortion can be compensated for by using torque plates when you hone the cylinders. John asked what block I was thinking of using for this repair process, and I told him it was a Hyland block. He said I would probably be okay with the Hyland block; however, in his experience, the Teksid and (I don't clearly recall, but believe he also mentioned) Nemak/Aluminator blocks were not good candidates for this type of repair.
His suggestion, if I were to use this on a non-Hyland block, would be one of the FGT/GT500 blocks because of their additional strength in the basic block and the upper cylinder banks in particular.
Bottom line, I believe, is that if you damaged a proletariat 4.6L block and needed to replace head studs, you would be better advised to replace the block and start all over — you would be money ahead in the game.
This is a drawing for a 1/2 x 13 NC, 7-inch long, long-reach tap from McMaster.
This is not a thread-forming tap, which is the type of tap you want to use for this type of job. The price for this tap is $109.85. You will need two plug taps and two bottoming taps, which in the thread cutting tap corral will cost approximately $439. Add another $20 to $50 each for thread-forming equivalent taps. That pricing is for a 1/2 x 13 tap. I could not easily find a long 9/16 x 12 tap (they do exist) in either a thread-cutting style or a thread-forming style, which means they are available but at an even higher price.
That's not the end of the story. You will also need two long reach drills that are a
minimum of one drill size small or 25/64". McMaster prices those out at $45.64 each, and you'll probably need two, or possibly three, to be safe. Your non-thread-forming tap and drill costs have just reached $576.32!
Now that you have drilled the holes but not tapped them yet, you will need to ream the undersized hole you just drilled to size. Plan on using a minimum of two reamers, and if prudent, three. A long 27/64" reamer costs $47.19, and guess what, if you buy three, you'll probably only need two, but if you buy two, you will definitely need three. Your tooling price has just reached $717.89, and you haven't even made your first chip yet.
All the cutting tools notwithstanding, you are still in need of fixturing that accurately holds the block in place while you machine. Plan on spending $1,500 to $2,000 more before you have the fixturing in hand, ready to use. The ante at your poker table just hit somewhere between $2,200 and $2,700 to do this job.
What these numbers are telling you is that it is time to get a new block and not attempt to resurrect the old one. Once you fail, you will still need to purchase a replacement block. The only difference is that you will have flushed approximately $2,500 down the drain without any return.
By the way, you will need access to a large table Bridgeport with a Ram Riser Block sufficiently tall to accommodate the cylinder block to do all this work in/on ...
