Folks:
Latest on reassembling the new engine for the 6.
I have the engine basically back together, but narrowly avoided
making a couple of significant mistakes.
First near miss, I started putting the pistons together, and
thought "Oh yeah, better check the ring end gap". I thought that with
new 0.020" over rings and pistons, that the rings would be delivered at
the right size, but better double check. So, I put one of each of the
first and second compression rings in a bore, and use an inverted piston
to push the ring into the bore, then measure the end gap with a feeler
gauge. The 2nd compression ring was tight by about 0.003", but the
number 1 compression ring end gap was 0.000". Oops, if I don't gap them,
they are going to break when the engine warms up. I used my dremel with
a cutoff wheel, then squeezed each ring together so that the ends of the
ring were pressed on opposite faces of the cutoff wheel. It didn't take
much, and they were gapped. Whew! Dodged that bullet...
Second near miss; Installed the rings on the pistons, installed
the rods on the pistons per Bentley (arrow on piston crown points to the
front of the engine, the open face of the rod journal faces the
camshaft). Fresh wrist pins and circlips. So far so good. Using my
trusty ring compressor, insert each piston in the block, noting that the
rods are numbered at the factory and must be installed in the correct
bore (mother didn't raise any stupid children). Per Bentley, I match the
numbered rod cap to it's respective rod, being sure to orient the cap so
that the factory applied numbers are both matched on the same side of
the rod. Wait, what's this? Oh, the machinist also engraved numbers on
the caps, and yes the numbers match the factory numbers. Ok, to sanity
check the work, I will (grunt) just give the crank (grunt, huff, puff) a
little spin , cause Williams says it's a good idea. Son of .... Why
can't I budge the crank? Is it supposed to be that stiff?
To make a long story short, the machinist had reversed the caps
on 3 of the rods when he resized the big ends. He then applied a NEW set
of numbers to the rods. By installing the rods using the factory
numbers, I had the caps on backwards for three of the rods. Let me just
say that the bearings were more than a little *TIGHT* as a result. You
would need to be superman to spin that crank. By inspecting the rods
carefully, I found all the numbers that the machinist had applied, and
discovered that he too, had numbered both the cap and the rod, and that
the cap MUST be oriented so that the *machinist's* numbers are on the
same side of the rod, even if that means that cap is on "backwards"
according to the factory numbers. I probably would not have been able to
set the cam timing, but if they had not been that tight, I might have
been able to get the cam timed and then immediately spun a bearing when
I started the engine. Whew! Another bullet dodged.
Lastly, I thought I would mention that Bentley has a nice little
procedure on how to time the cam, without the benefit of any timing
marks on the cam timing set. Set number one cylinder to top dead center
(easy; the keyway in the crank snout will be pointing straight up). Then
set the notch in the cam nose to 4:30, like a clock. This will get you
very close to correct. Install the timing set, the lifters, head etc.
Rotate the crank until #6 cylinder is at TDC on the compression stroke.
Set the valve lash on #6 cylinder. Now rotate the crank back to TDC on
compression for #1 cylinder. Watch the valves on #6 as you rock the
crank back and forth. If you have timed the cam correctly, the exhaust
valve will be nearly closed on #6 and the #6 intake will be barely
opening when the crank keyway is straight up (at 12:00).
Now you would think that this is likely to be wildly inaccurate,
but in fact it turned out to be amazingly sensitive because the cam is
moving at only half the crank speed. It was easy to see that I was off
slightly (keyway was at 1:00 when both valves were almost closed), which
turned out to be only 1/2 of a tooth on the cam sprocket! I popped off
the big gear, rotated it ninety degrees (in effect, moving the gear 1/2
of one tooth) and tried again. Presto! Just like Bentley said. So if you
are like me, and toss the old timing set before transferring the timing
marks to the new one, there IS hope. Just read your Bentley.
That's it for now. Oh yeah, had to helicoil the front bridge on
the block (little allow block that the oil pan attaches to). Pulled out
the threads with only 5 lbft of torque. !@#$%$%.
Later,
Vance
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