Engine Restoration

By Staff

 Rt. #4, Box 268, Lillington, N.C. 27546

When beginning an engine restoration, the first thing I do is
replace any missing parts and repair any that are broken. It is
better to do this kind of work early than to try and do it after
you’ve done the other things like painting, etc. I also try to
make sure the engine runs about like I want it to.

It seems that everybody has their own remedy for freeing stuck
pistons, and other parts that are rusted together. Here’s one
the readers might want to try, and that’s soaking for three or
four days in apple cider vinegar (brown variety). Vinegar is
slightly acidic and will dissolve rust that has formed in between
the piston and cylinder wall and since it is thinner than oil, it
penetrates as well as most penetrating oils. Works good on pot
metal fuel pumps like those on some of the I.H.C. engines, too.

Next, I completely disassemble the engine. This is so I can get
to all the rust and dirt that can hide in the small parts in any
little crack or corner. The major parts like flywheels, crank,
head, etc. are put aside for later. Small parts like throttle and
governor linkage, mixer, oiler, etc. are put into a bucket or box
so they don’t get lost.

Bearings are marked with a scratch awl so they can eventually be
put back in their original location. Bearings and shims are tied up
with wire or string the same way they sat in the engine so they can
easily be reassembled. All this seems like an awful lot of work,
but I’ve found that it’s about the only way to get a really
nice looking restoration.

Now that the engine has been taken completely apart, it all has
to be cleaned up. I start with the larger pieces first, such as the
main frame, fly wheels and head. For this I use an angle grinder
with a wire cup brush. With this outfit you can take off heavy
rust, grease, paint and almost anything else. Unlike sandblasting,
which seems to open up any surface pitting, the wire brush seems to
have a smoothing effect on cast iron. If you want to go a step
further, a flexible abrasive disc on the same grinder can really
smooth out those old rough castings, but if you intend to use some
type of filler material, you may find that you don’t need to do
a lot of actual grinding on your engine. One important point to
remember during all this is that the finished paint job will turn
out no better than what is underneath it. For small parts and for
those areas that can’t be reached with an angle grinder and
wire brush, you’ll have to resort to sanding by hand or
cleaning with a hand held wire brush.

Once you get any one part cleaned of dirt and corrosion
you’ll need to put on a coat of primer to keep any rust from
forming back on the clean parts. I prefer to use a good quality red
oxide primer from a spray can, mostly because it is convenient.

Once the parts are cleaned and primed, the next step will be to
start filling in those areas that are pitted or are rough from the
casting process. One product that I like to use is Martin Senour
#3934, Red Oxide, Glazing Compound. It comes in a tube and is about
the same consistency as tooth paste. On flat surfaces the best way
to apply it is with a soft plastic paddle like body shops use. For
corners and any rounded surface the best way I’ve found is to
dab a little on the end of your finger and smear it on. Thin coats
of this filler will harden enough to sand in about an hour, thicker
coats will require more time. When using this or any other filler,
be careful to put on only enough to fill in those pitted and rough
areas since a big portion of what you put on will eventually be
sanded off in the process of getting all those parts slicked up and
ready for final painting. Speaking of sanding, that’s what
comes next. For this I use Autobody, Waterproof Paper, Silicon
Carbide in grits of 100, 220 and 320. To make your sandpaper go
further, you may want to do as I do. Cut a full sheet of paper in
half and then fold each half sheet in half again. This will give
you a piece of sandpaper approximately the size of a man’s hand
with grit on both sides. Soak your piece of sandpaper in water for
five minutes before you start sanding. This softens the sandpaper
and makes it conform better to corners and uneven surfaces. Anyone
who has ever tried dry sanding on primer or paint will tell you
that you can clog up a piece of sandpaper in about two minutes this
way, and make it completely useless. As you sand, dip the sandpaper
in water every minute or so. This will help to wash away the primer
and filler as you sand and keep your paper from clogging.
You’ll be surprised how long half a sheet of sandpaper will
last when used with plenty of water. Water won’t hurt the
engine castings, but you’ll find that rust forms pretty fast on
any bare metal that has been exposed by sanding with water. If
possible try to arrange this work so that the last thing you do
before putting everything away, is to put a coat of primer over any
exposed metal to avoid having a lot of new rust to contend with the
next day. Make sure that all surfaces are dry before applying

On engines that are badly pitted, this priming, filling, and
sanding may have to be repeated two, three or even more times
depending on how smooth you want the surface to be. But, for a real
slick looking paint job, you can count on doing it several times.
The first time you sand, you’ll want to use a coarser grade of
sand paper like 100 grit, and then change to a finer grit, such as
220 or 320 as the surface gets smoother. All this priming, filling
and sanding can be a lot of hard work, but remember the
rule-‘Your finished paint job will look no better than
what’s underneath it.’

After you’ve got all parts prepared like I’ve just
described, you’ll be ready to start putting on some color.
I’ve used spray paint in a can from several different
manufacturers, but I have two favorites. One is Krylon spray paint.
It works well and some of their colors are very close matches to
some of the old engine colors. Another favorite is Martin Senour
Automotive Enamel in a spray can. When applied correctly it has a
nice shine and is very durable. Martin Senour offers a wide variety
of colors including some of the standard tractor and engine colors
like I.H. red and J.D. green and yellow. Many good auto parts
stores can mix paint and give a pretty good match to most any color
if you can show them some kind of color sample to go by and if
you’re inclined to use an air compressor and a spray gun to do
your painting.

As far as the actual painting goes, regardless of whose paint
you buy and whether you use a spray can or a compressor and a spray
gun, the one thing you should try to do is put on enough paint so
that it looks ‘wet’ as it goes on, but try and be careful
and not let it sag or run. If you do get a run in the paint, go
ahead and let it dry and come back later with some fine sandpaper
and some water and sand the run oft. Then a little touch up
painting over this area should cover it up. If your paint looks dry
or ‘ ‘dusty” when it is being put on it will look
even worse after it has had time to dry out.

A little experimenting with paint will help develop your own
painting technique. I recommend three coats of paint on an engine
to help protect it from handling, weather, etc. I also try to paint
all parts before assembling the engine. Sometimes a part may get a
scratch as the engine is being put back together, but these can be
easily covered with a small amount of paint and a small brush. Some
people seem to prefer assembling the engine and then painting it,
but I like to paint some of the smaller parts a color that
contrasts with the color of the main engine parts. About the only
way I know of to do that is to paint first and assemble later. On
larger engines of say 6 HP and up, this taking apart and putting
back together can mean some heavy lifting, so you’ll either
have to have some help available or try and figure a way to do your
cleaning and painting while leaving some of the heavier pieces in

When you’re ready to put your engine back together, it’s
a good idea to have the engine skids or trucks ready, if possible.
That way you can go ahead and mount your engine on it and you will
have a good sturdy base to work with. If you know someone who has a
sawmill, it sure can be a handy source of good material for
mounting engines. I prefer to use white oak for skids since it can
be made to look good and is strong enough to do the job. On light
colored woods, I like to use some type of stain to darken it a
little and then after sanding, use satin polyurethane applied by
brush to seal the wood and protect it from swelling and cracking
due to weather changes. After the engine has been painted and put
back together the only thing that should remain will be those
little things that will really ‘dress up’ your engine.
Install brass grease cups rather than the painted steel type that
probably came on the engine when new. Shop around and try to find
brass to replace the original gas line, etc. Polish all brasswork
and then give it a coat of clear spray lacquer and that shine will
last for years without having to repolish it. Put on the correct
decals, and if you want to be a little adventurous, you may want to
try a few pinstripes.

The easiest way to pinstripe an engine is with the stick-on type
that can be found at many auto parts stores. Basically, it is a
thin plastic tape with a adhesive backing. It comes in
1/8, 3/16, ? inch
widths, single and double lines and in a number of different
colors. Be careful when putting it on and make sure you’re
putting it in the right location, since it can pull off small
pieces of paint if it has been taken off and relocated, especially
if the paint is very fresh.

So, basically that’s the way I do it, and most of it was
learned through a lot of experimenting to find what worked best for
me. It’s kind of like a fellow I once knew, bought a grain
combine that was completely worn out, partly for not knowing any
better and partly to save money. When he started using this
machine, he didn’t pick much grain, but he sure did learn a lot
about combines.

In restoring engines there are a couple of important points to
remember. Take your time and don’t rush. This causes mistakes.
Don’t spare the elbow grease. Your engine is well worth the
effort. Don’t forget to have what’s under the paint look as
good as you want the paint itself to look.

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Preserving the History of Internal Combustion Engines