Once again I was at a loss for the appropriate expression (@#$%^&%$#$%)
after finding that the two larger diameter through-bolts (tension bolt?
whatever) on my 20B had not ever been torqued.  I had mentioned a while back
that when running my engine on the plane I had noted a small coolant leak
coming from a through-bolt at the bottom of the rear housing.  With the rear
engine mount plate and re-drive mounted it was not possible to get a wrench
on it.

I was about to begin the process of removing the re-drive, etc. to replace
the seal, when, for whatever reason I grabbed a couple of wrenches to put on
the larger bolt at the top just to check what size it was (21mm).  As I was
fitting the wrench onto the head I thought I saw the bolt move.  No way.  I
flipped the wrench over and put the box end on the bolt – THE BOLT WAS
LOOSE!  It took at least a full turn to get to a torque of 25 -30 ft-lbs.  I
checked the 17mm bolts – they were fine.  After removing the starter and a
couple of the re-drive plate spacer blocks, I was able to check the other
bolts.  The bottom 21mm bolt that was leaking was also loose.  It took more
than half a turn to get it tight.

Best I can guess is that all the smaller bolts were torqued, but whoever did
the job, forgot to tighten the 2 21mm bolts.  It is just unbelievable to me
that an “expert” building up an engine for an aircraft could make these
errors.

I was upset by failed attempts by Atkins on custom exhaust and intakes, but
I rationalized that at least on the engine block he really knew what he was
doing.  But later found at least four major errors;

1. Installing 9.0 compression rotors in a NA engine instead of 9.7, and then
arguing that the lower compression was better.  I agree that at high rpm,
6500+, it won’t make any difference; but Mazda test data suggests about a 4%
penalty at my cruise range of 5000 – 5400 rpm.

2. A custom longer oil pickup tube for my deeper pan which was; a) too long
to fit in the pan (which he had in his shop), and b) leaked air around the
flange weld so the oil pump would suck air bubbles.

3. A front e-shaft pulley with timing marks that bore no relation to the
timing pointer.  I guess the because of a stock 20B pulley and a 12A front
cover.  This took some hours to resolve during the dyno testing.

4. And now the two tension bolts that had never been tightened.

I can only hope there will be no further “discoveries”.  The last time I
talked to David (months ago) he mentioned that he was no longer providing
engines for aircraft.  Good idea – just too late.  He did my engine about 4
years ago.

A couple of questions: Why are two of the bolts larger?  What is the torque
spec on these bolts for the 20B?  I seem to recall 26-28 ft-lbs.  I can’t
get a torque wrench on the bolts without removing the re-drive, engine mount
and flywheel, but I have a pretty well calibrated arm.

Al




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