Lets build another engine!

By Clinton HulleyVW Polo Classic Project Car
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I have been throwing a lot of thoughts around on what my next step was going to be. I thought maybe I must just build the same setup and make it as strong as possible. Then again what is the fun in that? I was looking for a challenge. The first step was to decide what to do. I found another Volkswagen 2.0 liter sub-assembly for a good price. The block was still stock bore and the crank was also not cut yet. The only issue I had was the crank was a cast crank. My engine in my Polo had an older and stronger forged crank in it.


Do what with the crank?

That wasn’t really a problem I would just have liked to get an engine with as steel forged crank. I was looking around for a while but just could not get one. The older forged steel cranks were getting very scares. I had to take what I could get. To see what I was sitting with I had to take the engine apart completely. I got everything cleaned and assessed the parts. The first thing I did was to knife-edge the crank. This is basically grinding the crank counter lobes on the frontal side, the side that basically hit the oil first.

This was a common mod that gets done to race engines. It helps the crank to cut through the oil splashing around in the crankcase. While an engine is running the inside of the crankcase looks like a spider web. The oil gets fringed off the rods and the crank. So making the counterweight sharp on the one side the counterweights cut through the oil like a knife. If you imagine how hard water gets if a flat surface hits it. It is almost like hitting a wall.


By grinding the counter lobs it also lightens the crank slightly. You will most probably say that it is such a small amount of steel that you grind off. Well, it all depends on the crank you use, some cranks have bigger frontal areas on the counterweight. You won’t believe what big impacts small weight changes have on your rotating assembly.

Knife edged crank

How to make the cast crank stronger

In the above pic, you can see how the counterweights I made sharper in direction of rotation. My next step with the crank was to get it stronger. I have heard of people that get a process of Nitrating done to the cranks. I found a supplier that could do this process for me. The supplier told me that there is a chance that the crank was going to bend. I told him to go ahead anyway as I had to get the crank stronger.

It was approximately 3 days later and the crank was done. When I got the crank back I put it in the lathe at work. I spun the crank with a clock gauge on the mains. The crank was as straight as it could be. I had one small issue now. The mains journals and big end journals had a rough texture to it. This would eat away the bearing shells quickly. When measuring the journals I also found that they grew bigger from the nitrate process.


How to clean up the bearing journals.

This was a good thing as now I had material to take off to clean up the crank. I took some 80 grid emery paper and I spun the crank slowly on the lathe cleaning the bearing journals. Did the two outside journals first so that I could put the crank back in the block with the old bearing liners. Then I used some Plastigauge to check the clearances.

I worked my way inwards until all the main bearing caps were on and the crank turned freely. Individually checked the standard bearings and conrods on the big end bearings as well. Now the crank was basically done. I oiled the crank nicely and put it in a plastic bag so that the crank won’t rust. The crank still needed to be balanced but I needed to get everything ready. I wanted to take it all at one time to the guy that does the balancing. So what to do next?


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