Chopper Forums

Restudding shovelhead rockerboxes:


Here is the stripped head in the milling machine. I taped up the spring & valve to minimize the chips going into the oil drains.
I put a dowel in the chuck to locate the original stud hole, and zero the readout.


Then I drill the tap drill hole to depth. I'm using "Keenserts", I don't recommend helicoils. so the tap is 9/16-12. drill for that size


Using the mill as a tap guide with a centre in it, I tap the hole to the bottom


Here you can see how the tap goes in, guided by the centre in the chuck


The finished hole. You can see the installation tool on the other stud hole


The finished job, with the keenserts installed to the correct depth, just under the surface of the head. Noe the tricky part is knocking those four little locking pins down into the head to prevent the insert from spinning. Make sure nothing sticks up proud of the head surface, or you'll still leak.
Don't forget to blow every chip out, even if you think none went in, the risk is still there. I blow & wash with brake cleaner, to get every chip still stuck in the oil out.


Here's the stuff i used: from L to R: Old stud, new stud, Keensert installation tool with keensert below it, and special tap(to me, anyway)
One tech tip: When using these keenserts, run a die down the new stud about halfway. The studs are made to lock into aluminum, and are REALLY tight when going into the keensert, as it's steel. A die will size the thread to help go into the steel, as it doesn't need as much interference when installed in the insert. Don't run the die all the way down the stud, or it will be loose.