re: big end float

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

	My most recent question in regards to rebuilding my 2 L GTV engine was
about the connecting rod's big end float measurement.  My Official Alfa
rebuild booklet sez that I should have have between .008" and .012" of
float but I didn't know how to measure it.  I got several replies
indicating that I lever the rod to one side and measure the gap between
the crank and the rod.  Jim Steck was very helpful in answering all my
questions and even encouraged me to try my skill at some 'hand machining'.

	Measuring the rods for float, I found two were at .008" and two were at
.006".  No evidence of galling anywhere, either on the rod or the crank.
 Since I had to take off the same amount from all 4 because the engine
had already been balanced, I picked to remove .004" from each.  This
should give me two rods at .010" and two at .012".  Jim recommended that
these should be the clearances - "looser for faster" engines (he said
that he sets his racing engines to .014").
  
	I measured the thickness of each rod (all the rods were within .001" of
each other), subtracted .004" to yield the new thickness.  A flat file
took them down to the final thickness, measuring after so many strokes
at 4 different points with my micrometer to make sure that I didn't go
to far out of whack.  Used my ceramic whetstone (always flat) to give a
nice polish to the side.  In fact, my side looks better than the factory
side.  On the factory side you could still see the deep grind marks.  I
did use my whetstone to smooth out the 'other' side before measuring the
original thickness.  I did find that the factory ground wasn't all that
flat to begin with.

	Rods 1-3 measured a float between .010" and .012" but #4 was odd.  If I
pushed the rod from the offset side, I'd get a reading of .014" but if I
pushed it to the other, I'd get .012".  Either the rod wasn't ground
parallel or the rod journal on the crank is a bit off.  Did look at the
cranks and I could see the large radius where the feeler gauge couldn't
go down to the bottom of the journal.  But I also saw that each journal
wasn't turned exactly the same as another, nor was the turning uniform
all the way around on the same journal.  And #4 piston was the one with
all the blowby and the rod took some combustion gases for awhile and it
might be a bit warped.  I asked Jim about this and his thoughts were
this would not be a problem.

	All told, I've probably removed the pistons/rod about 3 times as I try
to correct a different problem.  Everything is ready for the rebuilt
head to get on except that I really need an engine stand.  Right now the
engine is on top of a table and getting difficult for me to rotate by
myself.  And when I put the head on, it'll be even heavier and bulkier. 
The Hershey Car show (Pa.) is this weekend and I'm going up there to
look for a cheap engine stand along with some other odds and ends I
might need.

	The next engine rebuild should go a lot faster!  ;-}}

	Bruce

--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided