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Even though I'm not a rookie at this, I'm struggling with what I consider a real rookie problem.
 
I bought a complete engine kit from a well-known local VW parts house, which is made up of all aftermarket parts. It included everything but the case.
 
I'm having a tough time getting the cam drive gear to slide down properly on to the crank.  I've researched this thinking that I am doing something wrong, and have seen and read a few videos and links where all that was needed was to place the gear on a hot plate for a few minutes, and bam, the gear would slide right into place with a few light taps.  This is not the case with me. I cooled the crank by letting it sit in the freezer for about an hour, while at the same time, heated the gear to a suitable temperature.  As I attempt to slide the heated gear onto the crank, it will go on about 1/8" and then stop. 
 
Another bit of info, that may actually be part of the issue, is that the woodruff key took some serious force to get into the groove. At first, it wasn't even close to fitting into the groove, but I filed it until I could get it partially in, then I had to give it a few good whacks with the hammer to get it all the way in.  Maybe the woodruff key is still to wide, and the gear is getting hung-up on the woodruff key. 
 
So, just a few questions to help me out...
 
1. What should the clearance be for the crank and gear at the same temp?  I measure the crank where the gear should fit, and get a diameter of 42mm. The inside diameter of the gear is about 41.85mm. Is this too tight?
 
2. What should be the clearance for the woodruff key into both the crank, and the gear? I haven't measured this, but I think this may be the culprit.  Now I hope that I can get the woodruff key out of the crank, and file more off to get the proper thickness.

Hi CBDZ,

We have more and more of this custom-fitting problem as tooling wears, or parts makers get more casual.

You did the right thing by filing down the Woodruff key, and should have filed a bit more. File out the woodruff slot on the gear itself some.

Set your flywheel down on something solid, set your crank onto it using the dowel pins to locate the crank, and get yourself a propane torch and a big pair of slip joint pliers to handle the cam drive gear. Now, from the hardware store, locate a short, stout piece of pipe that will fit on the gear.

Drop on your full-circle bearing, dowel pin alignment correct. Make sure the steel gear has it's alighment marks facing outward, so you can see them!

Set the gear over the nose of the crank, and blast it for four to five minutes with the torch. Holding the gear with the pliers, match the woodruff key into the gear slot, place the pipe over the gear, and gently hammer it down. If it hangs up, heat it some more.

Generally speaking, that's how to handle a stubborn fit.

Good luck,

FJC