Thanksgiving (November) 2010 -
I bought an O-320-E2G from a
wrecked Grumman Cheatah. The engine
has 1855 SNEW, but that was spread out over 35 years. All of the
cylinders have been
replaced at various
times, which tells me this engine didn't get to fly a lot and likely
1/17/2011 - The hangar is starting
to look like an overhaul shop. The near engine is the O-235-L2C
was going to use on the Cub. The next engine is the O-200 that I
just finished that is destined for a Pietenpol.
The far engine in the middle of the hangar is the O-320 I'm about to
tear down to overhaul for the Cub.
The O-320 as received from Fletch
O-320 with accessories removed.
Oil Pan removed. Hmm.
Isn't there supposed to be a screen over this inlet?
Oh, there's the suction tube screen
laying on the bottom of the sump.
Accessory case removed.
Disassembled cylinder parts.
The end of the connecting rod on the left front that is ash
colored is from #3
cylinder, which has apparently been running extremely hot.
Cylinders. You'll note the
broken exhaust stud on the right front cylinder. Also note the
aluminum color of the
heads, all except for the back on on the left. That's #3 cylinder
which again appear to have been very hot. The
cylinder bore was showing a blue tint to it, which also indicates
exposure to extreme heat.
First look at the crank looks good.
Uh oh. That is a corroded cam
follower for the front pair of intakes. Both cam followers for #1
cylinders were showing some corrosion and the shared cam lobe between
them was spauled.
# 1 and #2
intakes were lacking about 3/16" of lift. The cam is junk and at
least two of the cam followers
are beyond help.
My analysis following the engine tear down today. #3 cylinder
looks like it has been running extremely hot.
The steel in the barrel is showing some heat discoloration, the wrist
pin is showing some heat gauling, and even
the piston end of the connecting rod looks like it has been so hot that
the oil on it was getting scorched. I am
concerned about what kind of condition the head will be in as that
whole cylinder assembly has clearly been
badly overheated. Additionally, there is some cam spauling, so
the cam and some of the followers are junk.
However, what I have seen of the crank so far looks good. This
engine is very much exactly what I expected
to see, so I am satisfied that it's a good buy. For now, the
case, the crank, and the cylinders are in the hands
of my good friend and machinist Doug to be miked and closely examined
so we can decide exactly what needs
to be done to put this engine back into new condition.
February 4, 2011 update - After measuring all the parts, the crank is
on the cusp of meeting spec, so may or may
not end up being ground. It has some service bulletins due, so
will be sent out for work regardless. There is also
some minor corrosion on the aft side of the prop flange that will be
ground out and the flange cad plated. The
cylinders are all well beyond spec for std, so will have to be bored.
The exhaust valves are worn out. The cam is
junk. Two cam followers are junk and 6 can be reground.
This is pretty much normal wear for a high time O-320
that spent a lot of time sitting. The work up looks like it's
going to run $7500 - $8000 to overhaul this engine.
February 10, 2011 - Still no pictures to show, but progress is being
made. The Crankshaft is now in the hands of
Aircraft Specialties. Bad news on the case as the bearing saddles
didn't pass muster. They were beat out .002 - .003"
beyond spec. Divco has the case so they can mill the halves and
line bore the crank bearing saddles and the cam
bearings. Add another $800 to the estimate, so now it's looking
like $8300 - $8800 for the engine.
February 23, 2011 - Aircraft Specialties will grind the crank .003
undersized. Brown Cylinder has the cylinders
for boring, install new studs and replace the valve guides. Divco
the case for machining. The 6 repairable cam
followers have been reground and the rods magnafluxed and sized.
I expect to have all parts back in about 3 weeks,
so hope to be putting the engine back together in mid to late March and
hang it on the plane in early April.
March 11, 2011 - Still nothing to
show for an engine, but there has been progress. Most of the
bottom end parts
are sitting at Doug's shop in Santa Fe. The case has been welded,
milled and line boared by Divco, then finished
with an acid bath and alodyne treatment. The crank was found to
be cracked, so the new/used one is here. Polished
at std, and epoxy coated in the inner bore per SB 505. Brown
cylinder is going to trade me a set of std nitrided
160 hp cylinders in exchange for the cost of reworking my old 150 hp
cylinders. For those interested in doing the
150 to 160 hp conversion, the cylinders, pistons, wrist pins and
rings are all different. Make sure you get the right
parts. I would get started assembling the engine this weekend,
but am currently tied up with the real job that provides
the funding for this project. In another week or so, you'll start
seeing engine assembly photos on this page.
April 2, 2011 - We finally
have all the bottom end parts. Doug came up and spent the day
helping me get
the bottom end of the engine
put back together.
Case halves. I love that
Case halves mated together with the
new crank and new cam, then set on the stand.
Accessory case about ready to
install. Sharp eyed readers will note that I have the fuel pump
rod installed upside down.
Yes, I did make that mistake, and yes, it did get corrected.
Doug installing the through studs.
Rods are installed, and accessory
case is installed.
I fabricated covers for the vacuum
pump and fuel pump mounting pads since I won't need either. The
transducer doesn't clear the side of the new Casper Labs angle oil
filter adapter. Doug will mill away some
of the oil filter adapter and we'll see if we can't get it all jammed
Note: I ended up buying a 1 1/2" oil filter adapter extension through
Vans to get it all fitted correctly. I could
have just as easily bought a 90 degree adapter for the transducer.
Either way, the cost was $70. This problem
got a bit mroe complex when I went to mount the engine. The
extension moved the oil filter too far so it didn't
clear the firewall. I removed the oil filter extension and
ordered a 90 degree drive for the tach. It was HUGE.
No way was it going to fit. I ended up sending the tach back to
UMA in exchange for an identical tach that
uses a different pulse count and got a transducer that screwed into the
access hole on a magneto, so it counts
pulses as the magnet in the magneto passes by. It works really
well and is absolutely accurate.
Bottom view of the engine minus the
April 9, 2011 - Oil pan installed.
Case masked off for painting.
Painted intake and valve cover drain
Painted valve covers, dipstick,
intake flanges, and mag clamps.
April 15, 2011 - Still no cylinders, but I was notified that they
shipped today, so maybe Doug will have them
ready for me to paint by next weekend. I shot the case black
April 17, 2011 - With no cylinders
in hand, instead I installed the accessories. Today it was
stick, alternator, starter, carburetor, and air box. That's all I
can do until I get the cylinders, probably or
Friday or Saturday.
Update: There is a 1 1/2" extension installed in the oil filter adapter
to make room for the tach drive transducer.
It had to be removed as it put the oil temp tranducer into the
firewall. Now the tach transducer won't fit. UMA
is sending me a transducer that screws into the Slick Mag vent hole,
but will also require swapping the tach for
one that is programmed for a different pulse count.
April 22, 2011 - I've finally got
the cylinders in hand. Doug did a nice job with the valves and seats,
is ready to go once they are painted to match the engine. I've
painted the steel sleeves yellow to match the plane,
then have them masked off in preparation for shooting the black.
My paint drying set up. Two
heaters blowing across the cylinders. It was enough heat for me
to cure the
yellow cylinders, then shoot the heads black in one day.
April 23, 2011 - The paint is cured
after sitting in front of the heaters overnight, so I'm moving them to
other hanger for assembly.
OK, I was a bit remiss about taking
assembly photos. It's hard to do when you hands are always
with either assembly lube or gasket sealer. Here we are hanging
the completed engine on the airplane.
The hoist crew. They also
helped me roll the hoist up from the other hangar with the engine
hanging under it.
The engine overhaul is now
completed, so this is the end of this web page. Future updates
will be on the
completed plane page.
Page 1 - The Cub
Page 2 -
- Firewall Forward
4 - Firewall Forward (page 2)
5 - O-320
Overhaul (for the Cub)
Page 6 -
Final Assembly (2010)
7 - Final Assembly (2011 page 2)
8 - Final Assembly (2011 page 3)
9 - Completed
10 - Later Updates and
11 - MOGAS vs
Composite Fuel Tanks
for Scott Grizzly Cub N143W