early 80's A4's block deck blister/bubble @ frwd stud hole!

[3rd Newport]

Hello Afourians, Friday, Dec. 20, 2012 11:00 am PST

This is my first post attempt; despite years of enjoyment reading the forums.

After recent purchase of our 3rd Newport, a '77, we had numerous engine failures bringing it home to it's Long Beach, Ca. marina.

Thus far, we have replaced water cooling jacket plate & it's accessory parts; impellar in water pump, & changed bogging 3-blade back to 2-blade 12 x 6.
With the increased RPMs came steam from engine; which was shut down and water was coming from 3 & 4's spark plug wells.

Disassembly found 1/4" hole in head & gasket that had never seated properly. While awaiting our parts (head, drill/tap kit, studs/nuts, gaskets & sealers) from Moyer, we adjusted the valves (looked like never been done), solvent bathed carb, & made a Schroeder valve assembly to test the manifold (currently still holding air pressure while sun warms it) and head after installing both; the head we hoped to install today.

BIG SCARY FINDING ON BLOCK'S DECK: Forward (by flywheel) port side's 2nd stud threaded hole has some wierd chewed mat'l removed around it's otherwise flat surface til threaded hole starts. More importantly, a bubble-like (1/4"ish)raised area of head's top surface at threaded hole was observed. I haven't measured it's height yet; but with recommended max gap of .005 for head to block, it looks concerning.
Yes, we got the double-gasket set. Is the .005 max gap before gaskets installed, or after gaskets in and torqued to the (newer?) 25 lbs?

QUESTIONS:
Has anyone seen such bubble bump (without any gaps/separations observed); & how to address/repair such???? We were thinking of sanding/grinding it down; if Afourians/Don think there is enough material. What do any of you experienced folk think?

Thanks in advance for any helpful input!

[Al Schober]

Newport,
First, welcome to the forum. I find it a source of experience and encouragement - those with Atomic 4 experience helping each other and encouraging others to keep these great engines running smoothly and reliably. Sometimes they even agree - when they don't, we learn from the differing opinions.
I think I've seen what you're seeing - most recently with a manifold stud. My take on it is that the end of the stud corrodes, causing fewer and fewer threads of the stud to carry the load. Finally it gets down to about 1 thread and the material in the block fails, raising the bump you noticed. If you look at the threaded hole, I think you'll find there are still plenty of good threads remaining in the block.
If so, the fix is easy. Smooth off the surface, run a tap into the hole (3/8-16NC) to clean up the threads, and install a new stud. I recommend you check all your old studs for corrosion on the setting end. Just compare the remaining thread length to that of the new stud.
Please let us know how you make out with this.