Between us, Russ Milham and I have three engines to rebuild. I have a Franklin 165 (6A4-165-B3) to rebuild for my Coot, Russ has his Continental O300 to rebuild for his Coot, and we jointly own a Lycoming 0320 for our Traveler project that needs rebuilding.
We looked at commercially available engine overhaul stands (example) and found that they cost about $200 for a basic stand, and a little less for a kit. These are probably fine, but we wanted a stand that could be disassembled and stashed away when not in use—shop space is getting scarce! And we wanted a stand that can be used with a variety of prop flange bolt patterns, and had more than two holes for bolting the prop flange to the stand. I agreed to undertake the project.
This post shows the construction of the stand. Rather than providing technical drawings, I’ll explain things with text, measurements, and photos, which should be ample information for others to build a similar stand. Here is what the stand looks like completed:

Bill of materials:
- One 7″ x 7″ x 0.125″ (11 gauge) mild steel sheet (prop flange plate)
- Three 3″ x 3″ x 0.125″ (11 gauge) mild steel sheet (foot pads)
- Three 1.25″ x 1.25″ x 0.25″ x 36″ mild steel angle (legs)
- Two 0.125″ x 1″ x 72″ rectangle mild steel (cut into cross-braces)
- One 1.5″ x 2″ x ~6″ block of steel or aluminum (shim fabrication)
- Twelve 3/8″ x 1″ grade-8 bolt, washer, lock washer, nut set
- Twelve 5/16″ x 1.25″ grade-8 bolt, washer, lock washer, nut set
- As required, metal primer and paint
Legs: The legs are constructed as two nested pieces that are bolted together, so that the stand can be disassembled into a relatively compact form. The short leg pieces are about 5.5″ long and the long pieces are about 31″ long. The -3 legs are cut at a 55 degree angle. A single cut is made at 5″ from one end and the cut is toward the long end.

(Another view.)
Here is how I cut the angle using a metal cutting bandsaw. A piece of angle aluminum was put into the vice to hold the angle steel at a 45 degree angle in the saw’s vice.

…and the vice was rotated to 55 degrees:

This one cut, thus, sets the proper angle for the stubby legs (that are welded to the flange plate), and the long legs (that are welded to the foot pads).
Prop flange plate: The prop flange must bolt to the top of the engine stand. This requires machining plate steel, to turn a rectangular plate into a circle (although you could skip this, if you wanted) and machining slots for bolts. I used 1/8″ steel for the flange plate, which works perfectly fine. You can go thicker, but don’t go any thinner.
First a note about prop bolt patterns. There are three commonly-used prop bolt patterns for small aircraft engines. I recommend machining slots that will provide for all three patterns. The standards come from SAE AS127D, #1, #2, and #3. Numbers 1 and 2 are used on Lycoming and Continental engines and are 6-bolt patterns, and #3 is used on Franklin engines and is an 8-bolt pattern. The bolts for all three are 0.375 (3/8″) diameter, and the flange pilot (the central protrusion from the flange) is 2.249″ in diameter for all three patterns.
Here is a sketch of how the plate can be machined:

The face includes a 6-bolt pattern with a circle diameter of 4.375″ for #1 and 4.75″ for #2 patterns. The pattern also incorporates four (of eight) bolts for the #3 (Franklin) pattern, with a bolt circle diameter of 5.25″.
So here is are the holes:
- Two 3/8″ slots from 4.1875″ to 5.4375″ diameter (these are the horizontal slots that are used for all three patterns)
- Two 3/8″ holes at 5.25″ diameter at 90 degrees from the first two slots (two vertically aligned holes that are used for the Franklin prop pattern)
- Four 3/8″ slots from 4.1875″ to 4.9375″ diameter at plus and minus 120 degrees of the first two slots
Note that you can make the slots longer. For example the four slots can go from 4″ to 5″, without problems, but don’t make the holes much bigger that 0.375″ (3/8″). The bushing diameter on the prop flange is 0.623″, and the six or eight bushings are the only contact between the engine and the stand.
Here is the sequence of machining:
First, beginning with a 7″ x 7″ plate, bore a 2.5″ pilot hole in the center of the plate. I held the plate in a four-jaw lathe chuck and located the exact center:

Then a pilot hole was drilled, and a hole of about 1″ was drilled. A 2.25″ pilot was then bored into the plate:

Once the pilot hole is finished, the four-jaw chuck is replaced by a three-jaw chuck to hold the plate by the pilot hole. And the square plate is machined into a round plate:

(I started machining the corners and realized it was going to take awhile. So I switched to a thick cut-off bit and came in from the side. Slow the lathe down near the end to prevent the corners from flying too far.)
The next step is to machine slots and holes into the flange plate:

Tripod Assembly: The next step is to weld the short legs onto the flange plate:

(More views here and here.)
The long legs can then be fitted to the small tripod. The long legs are fitted to the inside of the short legs. I used a belt sander to round the outer angle of the legs slightl where they overlap the short legs. This allows them to nest snugly.
Using clamps to hold the legs in place, move the long legs up and down until the top of the stand is perfectly level. Don’t skimp here!

(Another view here.)
…and drill four 3/8″ bolts to hold the legs together:

Next cut three 3″ squares of 0.125″ steel, and weld them on.
Bracing: Next comes bracing. There are several ways to do this, so feel free to figure out your own way. I chose to add two “layers” of bracing, one near the top and one near the bottom. I cut three pieces of 1″ x 0.125″ rectangle for each. Here they are resting in place:

(Another view here.)
Since the angle of the legs is 90 degrees, but the legs are spread 120 degrees apart, shims are necessary between the bracing and the legs. I chose to saw the shims out of a block of aluminum I had sitting around. Use whatever works for you. Here is a shim being test-fitted.

Slight asymmetries in the angle at which each leg was welded to the prop flange plate necessitated custom shim thicknesses.
Now, use C-clamps to hold the whole thing together and drill holes for the 5/16″ bolts. Here is the entire thing assembled (before trimming of the shims) with 350 pounds of semi-static load (I was bouncing a bit). The stand is rock solid.

The next step was to trim the shims, and stamp a label where everything fits, so it can all be reassembled without difficulty.
Finishing: The last step is painting the stand. The top of the prop flange probably shouldn’t be painted or else you may end up scraping paint off of the prop bushings after a rebuild.
I brushed on RustOleum metal primer (here and here) and then sprayed on a RustOleum enamel textured white.

(Another view here.)
Here is the assembled stand:

Using it: Within a week of finishing the stand, Russ and I had mounted the engine on it and pulled cylinders, pistons, and connecting rods. Splitting the case comes next….

(Another view here.)