--> Europa-List message posted by: "Area-51" <goldsteinindustrial@gmail.com>
So an update on the 914F tear down.
At first my initial thoughts were leaning toward operator error of insufficient
engine warm up prior to T/O where the lifter to crankcase expansion lag was
causing the lifter to not rotate; which was somewhat correct and not correct.
There is always a reason for early component failure. Determining the root
cause is not always that easy as there are often layers of factors to be thrown
into the diagnostic possibility field.
One thing noticed on the 914 while removing each lifter was how tight they each
were during extraction and insertion through the unused portion of the lifter
bore. Could this indicate the clearance upon assembly at the factory?
Some gauges were turned up on the Czech Hobbymat lathe. One gauge was made
oversize to determine unserviceable bore sizing. The other gauge was matched to
the 914's unused portion of the bore. It was a good exercise and with the added
benefit of learning how to perform 0.0005" precision passes.
In the end the gauge revealed that the engine left the factory with 0.00015"
operating clearance. This alone would prevent the lifter spinning in the bore
as required. Introducing lifter to crankcase expansion lag would reduce this
clearance further again. There is minor scuffing on the bore indicating metal
to metal contact binding.
With a cause now identified the lifter bores will be correctly sized and a new
set of lifters fitted and lapped to the camshaft.
Presenting the 914 CAD data into the 3D model does not bode well for the
Classic, with the turbo compressor and induction pipe impacting the passenger
footwell. Some bits will need to find a new posting.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511396#511396
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