Dumbo The Flying Elephant

[Larry Hill]

Patsy lamented that fixing between my ears is a lost cause.

[Larry Hill]

Assembling is easy it's getting all the parts to like each other is the time consuming part.

[J.R. Haddad]

Larry, that kinda sounds like when I have the In-Laws over.

J.R.

[Larry Hill]

I enjoy the documentation part of the build. Checking piston to valve clearance at different installed C/L. Sometimes moving the crank sprocket to a different Advance or Retard does not show up as advertised on paper.

[Larry Hill]

A weekend off from being a grandpa. I get to work on my stuff. First thing is finalizing my disassembly notes, I failed to do that last time and it almost cost me an unplanned disassembly.

[Larry Hill]

During the mock up portion of the build I always give myself an NHRA tear down. Placement of the indicator observing straight, perpendicular, and parallel is very important to have the lift check correctly.

[Larry Hill]

I bought this nicely done engine part and it gave me some flexibility in tuning. I installed it but couldn't get it to repeat. Even the face runout would not repeat. I checked everything and everything checked good. Long story short, the dowel pin was protruding out far enough to make the hold down bolt washer apply in uneven force to the cam gear causing the runout to be everywhere.
A lot of times the parts are smarter than me.

[Cglrcng]

Originally Posted by Larry Hill

I bought this nicely done engine part and it gave me some flexibility in tuning. I installed it but couldn’t get it to repeat. Even the face runout would not repeat. I checked everything and everything checked good. Long story short, the dowel pin was protruding out far enough to make the hold down bolt washer apply in uneven force to the cam gear causing the runout to be everywhere.
A lot of times the parts are smarter than me.

I would say you found that issue, so you were actually much smarter than the dumb parts. Did you choose to trim the dowel pin to alleviate the runout measurement issue? Maybe report what you found to the parts mfg., so they can at least attempt a workaround on that cam timing gearset? Just saying.

On some of our robots in FIRST, some of the transmission gearsets for our wheelsets we always, take to the mill when new and face the center contact surfaces, and all washers and bolt faces to make sure that both faces on each gear are flat and true so each gear meshes correctly centered on each gear they mesh with throughout the gearset speed ranges. They are rarely machined perfectly to our liking until we trim or face them up. Once we do, they work a ton better. And rarely do we see washers that are truly flat or true until machined flat on both sides as they are usually just standard punched parts. We will often use a stack of thin flat stainless steel shims to replace a cheap steel washer under the head of a centered gear bolt, and it will often make a perfectly faced gear run and mesh more true with less runout. Some of those gearboxes are 3, 4, or 5 speed transmissions where one main gear has to move outward against perpetually smaller, and smaller gears, and if that main is not perfectly square, it will not mesh correctly and quickly when shifting both up and down through the selected range.

[Larry Hill]

We, Harry Tune and myself, built and raced toy airplanes. We made our own pistons, liners, heads, pins with retainers, gaskets, tooling and fixtures. Bore size was .737” displacement was .34 of a cubic inch. We learned a lot about straight and round. We mixed our own fuel. Laboratory nitromethane is clear like water and makes more power than that yellow stuff.

That was a lot of fun!

Disassemble is moving faster now.

[Larry Hill]

In trying to make more power I know we need to raise the RPM level. To me that means paying attention to fits. Well I found this one by accident. The gears that go on the crank that drives the camshaft are black in color and have an ID that has been bored. Two out of the three gears still had portions of the ID still black in color and fit looser on the crank. I do have one that cleaned up on the ID and is a good sliding fit on the crankshaft. I don't know if that could be a potential problem at 150 Hertz, but just trying to keep everything straight and round.