Originally Posted by LS614
No no, sorry, I already made pucks, and those are fine, I meant will the helicoils fit. have other people used them? I just don't want to go straight through the side of my crankcase with some enormous drill bit
I forgot about the heli coils, honestly I haven't used them on any of my engines because I haven't had anything strip out, but the bit that's required to drill the hole out isn't usaully that much bigger than the hole so I would think you should have plenty of room to drill it and install the heli coil.
I would also put loctite on that coil before inserting it if you do go that route, just a little extar insurance for a secure set of threads.....
I just went and looked at an HT case I have and it looks like you should have enough of room to drill for the heli coils, I'm not for sure what size drill bit is neccesary for the 8mm thread inserts but from what I can find you will need a bit size of about 8.4mm to drill the hole initially so that doesn't seem to me that it would be on the outer limits of the case.
I will list the tap size first. Followed by drill sizes. The drill size is for cut taps. These are for the "nominal" hole diameter required, nominal being midway between the upper and lower tolerance limits for the minor diameter.
These are the drill sizes needed for heli coil inserts for metric bolts or studs.
Size_______________ Drill size
M2.5 - .45 __________#37 drill
M3 - .5 _____________1/8 drill
M4 - .7 _____________#19 drill
M5 - .8 ______________#5 drill
M6 - 1 ___________6.3mm drill
M8 - 1.25 _________8.4mm drill
M10 - 1.5 _____________Z drill
M12 - 1.75 _______12.5mm drill
M16 - 2 __________16.5mm drill
Use some type of cutting fluid.
The Heli coil OD is ~ 10mm, i.d. is 8mm, both are 1.25 thread pitch inside and out, so the 10mm metric fine tap plus a Heli coil insert yields an 8mm metric coarse threaded hole.
Here's the best info. I can come up with that may help you decide if you have enough room for drilling for the Heli Coil, I think it should work just fine but a little measuring will tell the truth of it so I hope this helps.
I measured some of my bits and here is the results I have fur ya...
The 8.4mm bit measures roughly 0.330/0.332 I think you could get away with drilling that hole with a Q
size bit which if I remember right measures 0.328/0.329 somewhere in that range.