Sorry for the confusing title, I'm not sure what the proper terminology might be. Basically, most automotive engines have 2 dowel pins on the back of the block that register the bellhousing so that the transmission input shaft fits perfectly into the pilot bushing or bearing in the back of the crankshaft. In days gone by this wasn't super critical as the input shaft bearings were simply roller bearings. Todays modern transmissions use tapered roller bearings so it's necessary to "dial in" the bellhousing.
Long story short, several manufacturers offer "offset" dowel pins that you insert into the engine block ( they are slightly undersized) and then dial in the transmission register on the bellhousing, turning the dowel pin to where it needs to be, then locking in the dowel pin. I want to make my own for 2 reasons. I think I can and I'm cheap. They want $30.00 to $50.00 U.S. for a pair, plus shipping, exchange etc. I was able to accomplish the machining of an offset pin, but I can't figure out how they get them to lock. The instructions from one of them says to " tighten the set screw until the pin is locked in place".
The part of the dowel that goes into the block is slotted so that it can expand, but I can't figure out how a set screw would accomplish this. Do they thread the pin on a lathe with a taper? Is the set screw tapered? I tried using a pipe thread tap and a male pipe plug to accomplish this, but the sizes of pipe thread aren't quite right for the job and I don't think that is what they are using. Some pictures below of the commercialy available dowel pins.
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