I heard someone say that one must drill and tap the engine block for helicoils and install them when replacing head studs.. I have a 308 shop manual and could not find reference to this at all. In fact the manual implies that you can re-torque the studs more than once or twice for that matter without the need to replace them Comments? Tom
On the VW air-cooled engine design, I think that that's a common thing to do (especially if pumped up) -- but not on 308...
No need to replace the studs, even when upping compression, fairly bullet proof and over engineered. Only ever heard of very few snapping, usually corrosion is the issue.
Thanks Guy's .. that what I like to hear.. already got my hands full as it is. no need for extra work. Tom
studs can pull out of block when torquing heads. It happens often with aluminum engines. How often have the heads been off? How many miles on engine? These are the factors to consider. There is another system that works much better than helicoils, but I cannot remember the name right now. Actually drill in a new threaded sleeve. Used on Porsche 911 motors.
Timerserts. They have a kit for the 11mm studs used on Ferrari. But, unless the studs are broken or pulling out, there is no need to mess with them. Leave that sleeping dog alone.
I think it's Timesert, and another one named Keensert as well. I've used Keenserts at work, and I can attest to their very robust construction, and positive locking method.
The problem with using Helicoils/Timeserts/etc is that it's a very tedious operation and there'd always be a chance you could drill/tap off center, or at an angle when done by hand. I've installed Helicoils before (for the studs on the air-conditioning compressor) but in order to do it correctly, especially for a critical component like a head stud, you'd really need to do the drilling and tapping on a milling machine.
Thanks For your input folks, No question access to a milling macine is the best way to insure accuracy when drilling and or milling. However there is another solution for those that do this type of work often but cant justify the cost of machine tools like a mill and that is a Magnetic base drilling machine. http://www.toolbarn.com/champion-ac35.html These are compact tools that are very accurate where drilling operations are concerned You just need to magnetically attach the unit on a ferrous metal base This can be a steel plate,which in turn gets bolted to the top of the engine block. Locate the hole/broken stud to the drill chuck with a center drill or some other pointer. Hit the magnet and presto ! portable milling machine (sort of).. Work like a charm and not at all too expensive compared to when I used to import and sell these types of machines. Another major plus is you can mount these tools in any position The only limitation Is ones creative ability to mount or find a suitable location for a steel base plate if required. Regards, Tom
if you are fixing just one stud, there are the other 9 studs on the same plane to which you can mount a piece of magnetic base.
No need for helicoils unless you've pulled the stud out of the block. In addition to drilling at the right angle and centerline, you also have to be precise with the drilling depth. Too deep, and there isn't enough stud above the head to thread the nuts onto. (I lost my GTV-6 mill to a shop that messed that up --- one of a series of blunders from a Fiatized Alfa dealership, as Alfa was dying in the US) That's one reason I always tell people to know where they can get an Italian car *competently* serviced *BEFORE* they go shopping for one.
