Originally Posted by
McCloud 85
Am I right in saying there is a type of long stud that isn't particularly good? From memory it's the type that has a flange around the point of the block deck, and when the studs are screwed down in - this flange seals (with an o ring) against a recess in the block surface. These are bad because you can get a false fastening as it can bottom out in the recess rather than the stud being fully home in the base of the block? I was told that the better type are the ones that have a groove around the stud at the block surface and an o ring sits in this groove and makes a friction seal against the sides of the hole drilled in the deck surface. Allowing the stud to fully sit home in the base of the block.
If anyone knows anymore the info would be good.
Correction : the second type don't have a groove at all. They are completely smooth all the way to the bottom and use a much bigger double 'lipped' o ring type seal where the stud goes through the block deck.. therefore no friction can be obtained at the block surface and correct torque figures obtained as the only contact point is in the base of the block. Has anyone had similar findings?
I'm not familiar with the particular stud type you are referring to but there are at least two diameters of O ring flange type. i don't recall the actual diameters but one of my sets of studs only fits one of my blocks as the block has a larger counterbore to take the larger O ring flange. on that block, the machining of the larger counterbore for the O ring flange has encroached into the cylinder head oil hole and it was necessary to plug the oil hole and then grind the plug out to make the counterbore circular. i've seen other blocks with that work done and spoken with others who have also had this type of block /stud.
of my other two blocks which have the same (smaller) diameter of O ring flange, the studs are different lengths. i didn't know that different lengths existed and bought set (from burtons) and, whilst they were the same thread, they only engaged for a short distance. i measured the ones I'd earlier removed from the block and they were longer on the bottom half (don't recall how much maybe 8-10mm). the shorter burtons ones were also causing the lower edge of the O ring flange to hit the counterbore in the block face and as the studs were tightened in a dial gauge on the deck face was showing that the deck was being distorted by tightening of the studs into the block. (there is a torque figure which istr is 50 lb ft0
i never worked out what was going on but got some longer studs and all worked out ok.
hope this helps - like i said, get the studs wherever you get the machining done and save many hours of head scratching!