I had an engine shop build a 105 series (1300) short block for my vintage racer Giulietta. The donor block had some moderate internal corrosion. I noted to the engine builder that the head studs had some corrosion at the base where the thread into the block. I suggested that we replace them first, but the shop owner felt this should not be a concern and could be dealt with later. Well, thousands of dollars have been spent and we are now at "later".
I plan to install a head and torque it down before I invest any more money. If any studs break, I expect we will have to disassemble everything that has been done so far in order to replace the stud(s).
Is head stud faillure common for these blocks, especially when there is evidence of cooling system corrosion. Can the studs be replaced, or am I better off to seek out another block and start over ?
Chuck in NC
I have a twin spark block with one of the front two studs snapped off due to corrosion. This caused coolant to spill into the camchain cavity where it mixed with the oil. The car's owner continued to drive and the cams wore most of the lobes off and did some damage to the crank.
Anyway the cost effectiveness of repairing the block is questionable. The stud is snapped deep down and it will be costly to remove. I've decided to remove all the studs and replace any corroded, but they are very tight. It is currently being soaked with penetrant. The studs themselves are not too expensive.
Britalia-- Your mechanic's reluctance to open this potential can of worms is understandable. Likely he is telling you that in his experience there is only the remote possibility of a corroded stud giving up, and that is PROBABLY the case.
My personal experience is that replacing Alfa head/block studs is a bit of a crap-shoot. They are not willingly removed and they do not always allow themselves to be easily installed. I had to remove all studs from a 2 liter twinspark block to enable repair and resurfacing of the deck and if I had to do it again... I probably wouldn't! We had to use all the playtoys: big acetylene torch, large industrial oven, EDM machine, proper collet-type stud removal tool, taps, large cheater bars on said tools, etc. I basically had to spend my way out of the situation. It was, as they say, an educational experience. You should also be aware that Alfa studs are manufactured with a slight upset in the pitch of the threads on one end only. This is to provide a one-shot, one-time, one-way, goes in but can't come out (at least not easily) installation that is not likely to reverse itself in normal service life.
That said, I was eventually successful and am happy with the results so far. I would not discourage you from attempting it if the installer is familiar with the esoteric ways and pitfalls of placing steel into alluminum surrounded by water. Machine shops which cater to Jaguar and Porsche pieces come to mind as they apparently have their own set of similar "experiences".
Thanks for sharing your insight. Your thoughts seem to fit well with what my engine builder suggested when I requested that we replace the studs. When he cautioned against creating a new set of problems, I asked him to test the studs by torquing down a head to the block, before we threw lots of money at it. The studs are not severely corroded (less than 10% reduction in diameter), but enough to raise a concern to my untrained eye. For some reason he did not get around to testing the studs, and now it is a bit late given all the machine work that has been invested in the block. Hopefully these head studs will hold. If not, I will take your advice and look for another block.