If you have switched model year engines at some point you'll know there were a lot of minor changes here and there which cause headaches at every turn. Since the 86' block uses the eccentric timing belt tensioner it requires a mounting stud and collar nut (#8 and #9 below) for the block. The stud part # 944 102 243 00 is generally difficult to find and is supposed to be no longer available. The specs for the stud are M10 x 1.5 thread x 101mm long. (On very early model cars it was 106mm long).
I was able to source some ASTM A193 Grade B7 (which is a bit better than 8.8) M10 x 1.5 yellow zinc chromate plated steel rod from McMaster Carr (#98942A116) which I will use to create the stud.
First step was to measure and mark with permanent marker the desired length of rod (I choose 106mm) as this gives a little extra wiggle room and you could easily fit 110mm without any clearance issues.
Next I grabbed a piece of scrap 2x4 and drilled the nearest standard size hole in the 2" side (I mostly only have standard size drill bits laying around). Then take a wood saw and cut a slot down the center of the 4" side. This will be where the hack saw will ride when the rod is mounted to our wooden jig. Place the rod into the jig noting your mark for length, looking for it in the center slot with a flash light. Now is a decent time to double check with a ruler or caliper the length to the center cut to ensure you got it right. Secure the rod with M10 nuts on each side.
I then clamped the jig in a bench vise and used a jack stand to hold the extra rod up as this piece was 1m long. Using a hack saw cut through the center slot. Once completely cut you can use the nut which is already threaded on your new stud to help clean up the threads. Sandpaper or a file could also be helpful if the cut was not very clean.
Presto! A new 106mm stud without any damage to the threads from clamping.
As for the collar nut (aka flange nut, aka shoulder nut) Part # 944 102 243 00 it is 13mm overall height. This is not exactly a common size for a M10 x 1.5 flange nut. Solutions for this are to either stack a 3mm thick washer behind the more common M10 x 1.5 (10mm overall height) flange nut or to buy the part from Porsche, Pelican, Auto Atlanta..etc. As of 7/2016 the nut costs about $8
Special thanks to Van Svenson for measuring the stock collar nut.
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