Let's make a 4 cylinder flat

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Well I had one of those days.
I wanted to make eight 0.250 diameter X 0.750 long brass nipples for the intake and exhaust ports. There is a 1/4X 28 thread on one end 0.500 long and a 3/16" through hole.
Doesn't seem too hard right.
I ended up making 12 bushings before I got 8 that were good enough to keep so I took a picture of each one of them.
View attachment 153144

View attachment 153145

Sure glad that's over.

Thanks for looking

Actually, that sounds plenty challenging - between the 3/16" through hole and the minor diameter of the 1/4-28 threads, you have a very thin wall. Well done on only scrapping 4! :)

Sounds like it was an "exhausting" day ...

Kind of jumped around today starting with the intake system.
I soldered some 1/8" copper 90s on the intake brass nipples.
I am still not sure exactly how the rest of the intake assembly will be made.

I then went to the electrical system and mounted all the components.

Hooked up the ground and added an on/off switch.

Rechecked the valve timing and sequence of firing. 1-3-2-4.
Adjusted the ignition timing at just before TDC and I am getting a good spark.

Thanks for looking
I have finally decided on the intake manifold. I wanted all the runners to be close to the same length and with the same amount of restriction. Here are the parts I made for the manifold.

And a few views of the finished intake and carburetor.

This is similar to what I did on my 5 cyl radial engine's intake.

I also added some brass collars at the head end of the exhaust pipes to hold them securely in place.

I will be gone for the rest of this week but I will be checking in daily.

Thanks for looking
On my models that require a throttle I have been kind of lax. It is usually at the end of a project and I just stick a piece of metal up somewhere to operate the carb throttle. This time I wanted to make a smooth operating and hopefully a nice looking one that is easy to adjust and stays in place.

I also had some time to start on the gas tank. I still need to make the clear ends and a stand for the tank but I ran out of steam for today.

Thanks for looking
Well the engine does run but there are a few things that need to be sorted before the unveiling.

Distributor cap keeps falling off.
I have the dist cap held on with some electrical tape for now but when I am sure of the location I will a fix better.

Cylinder # 2 has a low output.
Cylinder #4 has no output.
I will pull the pistons and heads on #2 and #4 to see what is going on.

Cylinder #4 valve spring keepers/lifters are too short.
I will make longer lifters for #4 valves.

Fasten plug wires for neatness

Cylinders #1 and #3 are pulling fine so I am half way there.

Thanks for looking
I remade the valve spring keepers on cyl #4, lengthening them by 0.070 and realigned the cam shaft.
I couldn't find anything wrong with cyl #2 but I replaced the o-ring anyway.
Fastened the plug wires as best I can, they don't look too bad.

I put everything back together, started the engine and ran at least 6 tanks of gas through the engine today trouble shooting some new issues.

Cylinders #3 and #4 are firing nicely but # 2 is still weak.
Cylinder #1 has no spark and is pumping raw gas out the exhaust.
The cylinder would fire sometimes but not all the time which lead to the flooding condition.
I closely inspected the distributor and came to the conclusion that you get what you pay for. I may try to modify the dist first but if that doesn't work out then I will make one of my own design.

I will be back.
Thanks for looking

I have made two major changes to the engine starting with the distributor.
I decided to try to close up the gaps the spark had to jump to get to the plug. The way it was made the spark had to jump over 0,050 in two places and then still have enough pep left to fire the spark plug.
This picture shows the rotor with the new copper wiper I installed that is 0.040 higher than the original. The bent up staple (that's what it looks like) was the original wiper and it was in bedded down in the plastic.
The spark now has a combined jump of 0.020 not 0.100 to make before the spark plug. Miss fires are a thing of the past.

The next change was the flywheel there was not enough mass for smooth running.
The new flywheel weighs over twice as much as the original and about the same diameter. You may ask why didn't I just go to a larger diameter and the answer is this is the only piece I had.


The engine doesn't like to run below 1200 rpms as there is a problem with the fuel distribution to the cylinders. Cylinder #1 is running too rich and cylinder #4 is running too lean. I will be investigating this issue in the future and I believe it has something to do with intake manifold.

I am not very good at taking videos so be kind.

Thanks for looking
Congrats on getting all 4 to fire, the Video looks good to me, its not shaking all over the place like some, and its nice and clear.
The length of the intake runners could be a problem with it running rich and lean, also wont help with slow running.
Runs very nice ! Congratulations on your excellent work and results.
I'm about to make cylinders for my inline engine. There is one caveat with making cylinders from aluminum. If you use any kind of lubrication at all, the cylinder will never stop leaking an ugly black sludge that is mostly lubricant mixed with very fine particles of aluminum from the inside of the cylinders as they wear away. Cast iron has a high graphite content in it's make up, and that graphite provides a lot of the lubrication. Most people I know use either an all cast iron cylinder, or an aluminum cylinder with a cast iron liner. High revving engines use an aluminum piston, slow revving engines use a cast iron piston.
Hello, long time watcher but new poster.

The trick with Al pistons in aluminum cylinders, or any piston in Al cylinders, is to use high silicon aluminum alloys.

Silicon in aluminum, like carbon in Iron, has a limited solid state solubility. Another example is 360 brass. Once solid, the lead becomes insoluble and acts as a machining lubricant.

Back to the cylinders, high Si aluminum forms little beads of silicon upon cooling.

The cast iron forms graphite flakes upon slow cooling.

Put them together and you have an aluminum block and piston with similar coefficients of expansion and you have slippery cast iron that removes surface Al during run in and then glides from silicon bead to silicon bead on a cusion of graphite. The microscopic irregularity of the cylinder even helps maintain the oil film integrity.

What a wonderful and approachably presented build, thank you for sharing.

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