Porsche Track Car – Part 6 Engine Evaluation

Once I had the engine out of the car and dis-assembled into its basic components, it was time to do an evaluation and see which way to go next.  As far as I could tell, the cylinder head and cam tower were in good shape.  The cylinder bores looked fine visually.  I used a bore gauge to check for out of round, wear, and taper.  They measured out pretty well, considering the age of the engine.  The crank, rods, and pistons looked fine.  So I was left with the balance shaft issue.

I did some reading on Rennlist and other places and came to the conclusion that the balance shafts were really not “mission critical” for a track car.  The consensus seems to be that the balance shafts dampen vibrations at the middle rpm range, with the dampening effect being aimed at the comfort and refinement for the passengers, not due to any hard requirement for engine durability.  That said, there was some anecdotal information of oil pickup tubes breaking off more frequently on cars with the balance shafts removed or not hooked up.  This was considered to be caused by an existing tendency for metal fatigue at the pickup, exacerbated by the increased vibration without balance shafts.  To ward off this issue, I decided to buy a new oil pickup tube.

So what to do about the damage in the area of the balance shaft?  Call me cheap.  Call me foolish.  I decided to try the JB Weld approach.  But first I sent all of the parts to a local machine shop with instructions to hot dip them and evaluate the head.  I got the parts back from the hot dipping process pretty quickly.  I left the heads to get new valve guides and have the valve seating surfaces ground.

With parts back after the chemical cleaning, there was still a lot of gunk on them, both inside and outside.  I decided to put everything through my blast cabinet, using glass beads.  With some effort they cleaned up pretty well.  Here they are in some photos I took.

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I should mention that after bead blasting the parts I had to be sure and get the remaining blast media out.  I washed the parts in soapy water, rinsed them with a hose, and dried them with my compressed air hose.  Finally, I sprayed them down with multiple cans of Advance Auto brake cleaner.

At this point, I was starting to understand that a relative weak point of the 944 engine is an oiling system that results in the loss of the #2 and #3 rod bearings.  There are several remedial fixes for this.  Cross drilling of the crank journals for #2 and #3 seems to be highly recommended.  I decided to forgo this expense for right now.  I did invest in a sump baffle from Lindsey Racing.  Here are some pictures of how it looks after it is installed.  I had a local shop do the welding.  Sort of ugly welding but I suspect it will hold up fine.

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With the stock Porsche pan baffle re-installed

That’s it for now.  Next time, the JB weld repair.