1954 Advance-Design.com

Chevrolet 216/236/261 Engine
Crank Shaft Drilling Jig


Parts and tools for drilling/tapping the "front snout" for a bolt to hold-on the harmonic balancer
Included are tools to install the harmonic balancer


The setup is Jerry's (Stovebolt.com: Hotrod Lincoln's) first attempt at building a drill/tap jig (pre-2011), so it's kind of primitive (Jerry's words). 

Here are the numbers and an identification of each part:




middle

5 & 6.  Short pusher screw and attaching bolt: Works best with V-8 engine balancers.
 
7.  Plug tap for doing about 90% of the threading.  The first few threads are limited depth to start true and run straight.  Turn the tap about 1 turn, then back up 1/4 turn to break the chips off.  Use lots of threading lube like Rapid Tap or Tap Magic, or 90 weight gear lube to keep the tap from getting dull or breaking off.  If it gets hard to turn, DON'T FORCE IT!  Use spray carb cleaner or brake cleaner and compresssed air to flush the chips out several times during the threading procedure.
 
8.  Bottoming tap to finish off the thread.  It cuts the last few threads to full depth.


The two guide bushings (6 & 10) for the drill bit (9) and taps (7 & 8)  are slightly oversize on the inside, so a couple of layers of masking tape or electrician's tape on the crankshaft snout will help them have a snug fit.

The Woodruff key in the crank also needs to be removed to use the guide bushings. 

The other (newer) kits have a key slot so the Woodruff key can stay in place. 




top tools
 
9.  Tap drill bit.  Use a variable speed 1/2" capacity drill motor with plenty of lube and heavy forward pressure to drill the crank snout.  Make the hole about 1 1/2" deep.  If it's not making chips, you're not using enough forward pressure.  A drill bit that "skates" without cutting is just dulling itself.
 
10.  Pusher nut.  Use with part #1 to push the balancer onto the crankshaft snout after installing the timing cover and the front seal.  Use a little oil or Never-Seez on the crank snout and the pusher thread.  Be sure the keyway is lined up with the Woodruff key.  The turning force will get very tight when the balancer contacts the timing gear.  That's as far as the balancer will move.
 
11.  Long-thread pusher for 6-cylinder engines.  The short one is a little too short for some 6-cylinder balancers. 
 
12 & 13.   Bolt & nut to attach the long pusher screw.  Bolt the pusher(s) firmly to the end of the crankshaft before using the big nut to push the balancer on.





tools

1.  Needle-bearing pusher front:  It fits on the front of the pusher nut (part #10).  The bearing locked up some time ago, so the nut just turns on the brass ring.  Use some grease or Never-Seez there.

2.  Drill or tap guide #1 (marked on the front side): Can't tell which is which from this angle.
Size is stamped on the front.  One has the drill size, the other says "7/16-20" indicating it's for the tap.
 
3.  Drill or tap guide #2 (marked on the front side): Can't tell which is which from this angle.
Size is stamped on the front.  One has the drill size, the other says "7/16-20" indicating it's for the tap.
 
4.  Pusher adapter for the 216 and early 235 balancer that have the hand-crank lugs:  To use a center bolt on this balancer, a step needs to be machined in the crank lugs for a washer.  If folks don't have access to a lathe, I can do the machining if they send me their balancer.  A hand crank probably won't work once the center bolt is installed without some modification to the hand crank.





bits

7.  Plug tap for doing about 90% of the threading.  The first few threads are limited depth to start true and run straight.  Turn the tap about 1 turn, then back up 1/4 turn to break the chips off.  Use lots of threading lube like Rapid Tap or Tap Magic, or 90 weight gear lube to keep the tap from getting dull or breaking off.  If it gets hard to turn, DON'T FORCE IT!  Use spray carb cleaner or brake cleaner and compresssed air to flush the chips out several times during the threading procedure.
 
8.  Bottoming tap to finish off the thread.  It cuts the last few threads to full depth.





ŠTim Lederman 2013 - 1954 Advance-Design.com