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What makes your mechanic think you need new studs? Are they visibly corroded? Or otherwise damaged? Over all the years I've removed and replaced cylinder heads on L-head Packards I think I've only ever replaced two or three studs that had obvious problems.

Mechanics with modern cars automatically replace all the head bolts. That is NOT needed with any vintage Packard unless the bolt has actual damage. Standard procedure with a Packard flat head eight was to supply a new head gasket and torque the original nuts back on the studs.

I am not sure why the mechanic felt that new studs were needed, except that maybe he was afraid that the current ones would get damaged in removal. He is planning to remove the studs to more easily clean the block surface so it can mate to the newly cleaned and boiled head surface. I ordered 38 new studs as well as 38 new bolts from Max Merritt this morning.

I will say that no one there knew anything about "rolled threads" as noted in an earlier response. Does this sound strange to anyone here? MM parts guy assured me that MM had sold LOTS of these for the 48 to 54's and no one has returned the studs for any leak issues. I decided they must be okay and went ahead with the order. What do you think guys? Am I in for some grief??

rolled thread description

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Well now I am thinking that they are the 'new' rolled type... the MM number is 403255, just the same as the new number noted in the Packard notice you posted H.H. Seeing as my car is a 50, it could only use the new style.

Probably all that is available anyway unless Kanter has them. If they say no issues, then they should know. What I didn't see on theirs is the "hood" that looks like it is sort of protruding over the top thread and then what seems to me to be a left leaning slope of the rolled threads as compared to the mostly straight up and down appearance of the cut threads.

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A good explanation of the two different styles.
http://www.portlandbolt.com/faqs/rolled-vs-cut-threads-bolts

I wonder if there is something more to them in Packards case. From the bolt store description, other than threads being smoother I don't see why they would be any more effective in reducing leaks for Packard to adopt them or why they would say they are not interchangeable with the older bolts.

A guess is that the internal threads are cut differently. AND the bolts are cheaper to make. The rolled thread seems a little meatier and would hold better and fill the thread indents more fully.

Rolled thread bolts or studs are used so that a good portionm of the SHANK (UNthreaded portion) of the bolt will be BELOW the top of the surface that it is screwed into. This keeps the surface of the block from distorting when the bolt or stud is torqued very tite. Otherwise there is threads of thebolt pulling against the LAST TOP MOST thread of the block and thus causeing the the last female threads to mushroom up out of the surface of the block.

THis distortion of the area around the female threaded portion of (in this case the engine block) can often be detected by running a razor blade over the hole. In many cases the distortion can be easily detected by this method.

Note that rolled threaded bolts usualy have a smaller diameter SHANK than the diameter of the thread. Usualy rolled thread bolt has LESS threads than a die cut bolt. Which allows for clearence at the TOP few threads of the FEMALE threads in the block.