Re: Big end float and other measurements

["Giller,Bruce C." <bgiller@domain.elided>]

Biba,

> Must admit this is going to sound a bit cynicaland it is, a little bit.

	I'm a bit on the perfectionist side with it comes to my hobbies - I
like to make things at least as good as the factory if not better.  At
least I don't have 'shipwright's disease' which would only compound the
problem...

> Bruce is going to vast quantities of work to make sure his 2 liter
> engine is going to be as in spec as possible.

	This is the first time that I've ever rebuilt an engine so I want to do
it 'by the book' the first time around.  So I'm going step by step,
measurement by measurement from the Alfa engine overhaul manual I got
from IAP.  I figure that these specs must be in there for a
reason...although the reasons might be on the spurious side.  And
besides, I've got tools that I haven't used yet and this is the perfect
opportunity to get them out.  I used my pilot bearing puller on the
flywheel tranny bushing instead of the grease method.

> He mentions he hand filed down the big ends so they all had the correct
> (and same) end float.
>
> Personally, I'd be more concerned now with the balance of the rods.
> Unless this engine / car is to be used for racing, doubt if there will
> be one iota of difference as to how the engine performs. And if it is a
> racing engine, a slight imbalance on any of the reciprocating parts will
> still be considerably more critical at say 7500 than the correct end
> float.

	Before I put a file to the rod big ends, everything had already been
sent off to the machine shop to be balanced - crank, flywheel, clutch
pressure plate, rods, pistons, etc.  To keep that balance, I took off
.004" from each rod so that the same amount of material was removed
(more or less).  The float varied between .010" and .012" except the
that pesky #4.

	The car will be mostly daily driver with a few (3 - 4 a year) sojourns
to Summit Point for some non-competition driving.  I might twitch the
rpms over the redline but not for very long.

	My local Alfa mech. said that if the engine was running ok before the
rebuild and there is no evidence of wear and tear, don't bother checking
the big end float.  As you can tell, I didn't listen to him.

	But my real nit-pick is the order of taking these measurements.  The
big end float could have been done with just the crank and the rods and
BEFORE I had everything balanced.  Same with big end bearing shells;
done before putting the crank in the block; would be soooooo much easier.

> (Now the cynical part). I've been waiting for Bruce to write to the
> Digest asking what to do because the liner protrusion is not within
> specs. The shop manuals always show this being checkedgenerally with a
> special tool incorporating two dial gauges.

	I would love to recount how I made my own special tool out of some
scraps I found but I just use a machinist square laid across the entire
width of the liner and a feeler gauge to see if the liner was above the
block.  If I could see light between the block and square, I figured it
would be ok since the specs seemed to indicate that it doesn't take much
to be 'above' the block.

> My opinion is that Alfa heads have to be virtually perfectvalve guides
> and seats, valves, head can't have ever been overheated (warped),
> therefore perfectly flat and cams fit in the bottom bearing shells
> without rocking, etc. The block (for a street engine) is critical but
> not nearly as much as the head. The block should be spotlessly clean,
> all mating surfaces should be clean and not pitted, all bearing
> clearances should be within specs, either a new oil pump or a carefully
> refurbished one, rods should be indexed and all reciprocating parts
> should be balanced (including flywheel and clutch).

	Wes I. worked the head so it should be in very good shape.  The block
was dipped/cleaned at the machine shop and I have cleaned up all the
mating surfaces, rods indexed (meaning #4 rod went with #4 big end cap
and went into cylinder #4 with the offset to the middle), nearly new oil
pump, everything that rotates were balanced.

> Engine stand: I use a fairly heavy duty Harbor Freight stand with a
> highly modified Alfa metal engine mount to support it on the exhaust
> side.

	I'd sure like to see how you fabricated your Alfa engine mount.  I need
to rebuild the Spider's engine next and I've got a Mig welder that is
gathering dust.  It'll be awhile before I can get to it for there are
about 3 other major projects in line before I can start on the Spider.

> Bruce, I applaud your 'carefulness', just suggesting what I feel are the
> most critical engine building items. And you're correct, the next one
> will go much faster.

	I'll let you know how well it turns out but there is a Greek proverb in
that you can't judge if a man is happy until he is dead.  Who knows how
long this engine will last.

	Bruce

	'86 Spider
	'73 GTV on the road to recovery

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