Tiny Inline 4 Cylinder IC

[stevehuckss396]

I did the same as George as far as the tubing goes. I ran a 1/16 brass tube down the radiator into a small glass bottle. Peewee runs unpressurized.

 

[kcmillin]

Thanks for the pics Guys! That seems like a winning idea.

George, where did you get that tiny Ford symbol from?

I may have curbed the problem a bit. My filler cap threads into a brass plug which is epoxy'd into the top of the radiator. The plug sticks down past the ceiling in the radiator, so when the water hits the bottom of the plug there is a cushion of air trapped in the top of the radiator, and the water has nowhere to go but out. What I have done is drill holes through the threaded plug towards the top of the rad, this should at least equalize the pressure. There seems to be much much less water coming out now, if any, but I think I will still require an overflow.

Another issue. With my starter. The engine seems to have a lot more compression now, and therefor much harder to start. The dremel o-ring starter is slipping more now. I want to keep the flywheel smooth, so grooving it is out of the question, plus I dont like applying the sideways pressure to the bushing.

What are the alternatives to this method? Some kind of dogbone setup?

Kel

 

[stevehuckss396]

Another issue. With my starter. The engine seems to have a lot more compression now, and therefor much harder to start. The dremel o-ring starter is slipping more now. I want to keep the flywheel smooth, so grooving it is out of the question, plus I dont like applying the sideways pressure to the bushing.

I used a slip or clutch bearing. A 1/4 inch rod is inserted thru the radiator and into the hub on the crank. The rod spins one way and locks up the other so it locks clockwise and slips after the engine starts and revs to a speed faster than the starter. You can almost make it out in the same picture.

 

[gbritnell]

Hi Kel,
I'm really surprised that your Dremel would start the engine in the first place.
The only positive fix that I can suggest is a one-way roller bearing clutch. They make them in standard inch and metric sizes. Looking at the picture of your engine you have the crankshaft sticking out quite a distance from the flywheel. Although they recommend using these bearings with a hardened shaft you might get away with using it on your shaft if it's a standard size. On my engines the flywheel is machined to accept the O.D. of the appropriate bearing and I use a hardened dowel in either a model airplane type starter or as is the case with my 302 I use a cordless drill.
I have used different methods for starting over the years and have found this setup to be the simplest one going.
I get my bearings from https://sdp-si.com/eStore/
They're under clutches/unidirectional, although you might find them elsewhere.
If your shaft isn't a standard size then the only other options would be to make a new flywheel to accept the bearing or make an adapter to bolt to your flywheel. In either case your crankshaft would need shortening.
George

 

[kcmillin]

Thanks Guys. Like an R/C starter. Unfortunately my crankshaft is .240". This is because I needed to go a littler further to true it up. I like the method of using a 1/4" dowel and a one way bearing sticking out from the shaft.

How about using a large ring gear behind the flywheel and an electric brushless motor, like a real starter on a car. If I setup the motor on a pivot, I could even use it like the real deal. Then I suppose there is the matter of finding a strong enough motor in a small enough size not to look goofy.

Maybe even a large brushless motor connected directly to the crankshaft. Could this be used as a starter, flywheel, and load device all in one?


Kel

 

[steamer]

Thanks Guys. Like an R/C starter. Unfortunately my crankshaft is .240". This is because I needed to go a littler further to true it up. I like the method of using a 1/4" dowel and a one way bearing sticking out from the shaft.

How about using a large ring gear behind the flywheel and an electric brushless motor, like a real starter on a car. If I setup the motor on a pivot, I could even use it like the real deal. Then I suppose there is the matter of finding a strong enough motor in a small enough size not to look goofy.

Maybe even a large brushless motor connected directly to the crankshaft. Could this be used as a starter, flywheel, and load device all in one?


Kel

I suppose it could Kel. The little brushless motor in my son's 1/18th scale RC truck pulls 90 amps at 7.4V peak!.....damn near 1 HP at 40000 rpm...Do you know the torqure requirements to turn you engine over?

Dave

 

[kcmillin]

Do you know the torqure requirements to turn you engine over?

Dave

I am not sure. How would I determine that?

Kel

 

[steamer]

Thats a tough one Kel.

What do you have to measure torque? maybe a torque wrench or a fish scale and some string around a pulley?....maybe.... if you can figure out how much torque to pull past dead center on compression and double it, you should be good to go to size a motor.



Dave

 

[Lakc]

A beam or dial type torque wrench would be the ideal way to measure torque. Once you have that, you can divide the torque required by your ring gear to pinion ratio.

 

[kcmillin]

I don't have a beam torque wrench in in-lbs. But I do have an in-lb screwdriver. I will have to get it calibrated since I do not trust it at the moment.

Good news with the radiator. I made an overflow tube as per the usual. ;D
Once installing it I then ran the engine long and hard, and it did its job quite nice. I also noticed that when I put the end of the tube in a small container with water in it, when the engine warm up it bubbles a bit and lets some coolant out, then when it cools down, almost immediately the water gets sucked back up into the radiator. Hooray!!

Now I just need to do some more 'Testing' :big: to figure out how big of a container I will need. The cooling systems capacity is 13cc, pretty small, but so far it seems to be enough.

But first, a water pump re-build is in order. The bushing is completely slopped out. Miraculously it managed not to leak until after I showed to some V.I.P's, but I will need to install a new bushing. Since the wear is corresponding with direction of the belt which holds tension, I will make the bushing longer, protruding outside the pump. I will then need to countersink the water pump pulley to compensate for this.

Currently the water pump pulley is overdriven from the crank, and this little bushing is hitting over 10,000rpm, there is a lot of forces. The original shaft was untouched 1/8" drill rod. What is the surface finish of raw drill rod?? I am going to make a new shaft using some 1500 and 2000 grit sandpaper to eliminate any surface imperfections, and possibly using a larger pulley to slow it down a bit.

My method of joining the acetal gear to the shaft is by taking a razor blade and scoring the shaft lengthwise where the gear will be. This gives raised areas on the shaft which grip the acetal gear quite nice. until you take it apart a few times that is. I will also be making a new gear, luckily I made the gear blank long enough for a spare or two.

Kel

 

[jpeter]

To measure torque just wrap a string around the shaft and pull with a weight or spring scale to measure how hard you have to pull to adaquatly spin it. Multipy the scale or weight reading by the radius of the shaft and you'll have calculated torque. Seems like a brushed type dc motor has more starting torque than a brushless type. Brushed is cheaper too cuz you don't need the control.

 

[Jared]

How about a gearhead motor for a starter? You can find pretty much any size, torque, or rpm you want.

 

[kcmillin]

Thanks Guys. I think the string method is a winner. Once I get the engine put back together (Yes I took it apart again, more on that later) It will have new o-rings installed and should by the 'tightest' reading I can get.

Jared, good idea with the gear motor. However I would like the starter to be a permanent fixture on the engine, and most gear motors are about the same size as this entire engine (OK a little bit smaller, but too big nonetheless)



Now, I have ran the engine many times, and vary hard too. I have decided to run the engine as hard as I possibly can, while it is on the stand. I am looking for the proverbial 'Weak Link'. A few things I have been doing is advancing the timing to a point of knocking. This should create a lot of forces on the pistons and connecting rod bearings. Also, extended periods of 'load', By holding a piece of rubber on the flywheel, and holding the engine at full throttle working the engine very hard. This usually will start the cooling system to a boil, then I keep going for as long as there is a sufficient amount of water in the radiator.

This morning I decided was the time to tear it apart, but first one more run. I got the engine up to 7800 rpm, then I held it there for 2 full tanks of gas, adding water as necessary. This was about 45 minutes of full throttle, no holds barred engine destruction. I thought for sure It was going to break somewhere, but it just kept going.

So, on with the tear down report.
I was very pleased to find my new connecting rod bushings are holding up beautifully. There was a slight slop in a few which I had shimmed. I removed the shims and there tight, and move free.

The wrist pins are showing wear, and will be replaced. I have not drilled any oil holes for them, so this is not a surprise. Holes will be added this time.

The o-rings are indeed wearing out, but I don't think this is what they were intended to be used for. They do work quite well, and do last a decent amount of time. Had I not been so hard on the engine, they would not be so bad.

The bronze idler gear shaft has significant wear, and has been replaced with a drill rod shaft. The brass gears have some backlash, unacceptable for NASA but good enough for me. These will eventually be replaced by a combination of 12L14 and 7075 Ali.

Both bronze bushings on either end of the engine are in great shape, and do not need replacing.

The valves are looking good as well. I may replace a couple rocker arms though.

Water pump is still holding up, and the overflow system is working perfectly.

Camshaft looks good, but the leaded steel tappets are slightly mushrooming.

So all and all I am pleased with the engine. I would still like to find a few more weak links before I decide to go full out with plans.

The biggest problems I am experiencing is with the spark jumping do to flooded spark plugs, or plugs that just don't want to work. I am realizing there is a reason that R/C manufactures don't put ignition systems on engines this small.

Also, the carb could use some refining, but I do have the fuel tank 2 inches below the venturi, so that could have something to do with it.

Kel

 

[Lakc]

When we test we learn, so I am really glad to hear you thrashing it about.
You might want to just monitor the tappets. 12L isnt really known for work hardening, but I imagine there could be enough where the initial wear rate would diminish. The rest you seem to have well under control.

 

[kcmillin]

Got her back together again.

Reset the cam timing, I had it advanced one tooth on a 30 tooth gear. I was wondering about it for awhile there. It must have been pushing exhaust into the intake manifold and into the carb. Now the valve overlap at top dead center is almost perfect, no more than a couple degrees off. Even with the 260 duration, the exhaust valve could open a little sooner. I have yet to make a 260I-280E Cam. FWIW I also increased the lift by .003" for a total of .040" lift.

I also made a few more spark plugs. For some reason there were just a few Bunk plugs. After replacing the engine runs much better.

I am still using the third generation Carb, with homemade needle. This should be replaced by a sewing needle soon. I have not yet made it to the sewing store :big:

So, here is the latest video of the TI4. I have it running good, then I flood the engine to show the new ability for it to flood without spark issue. HOORAY! Shortly after that I touch the battery, and it don't like to be touched, because it kills the engine. But it is running much much better.

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Thanks For looking folks. I have two more related videos uploading now.

Kel

 

[kcmillin]

Here is a vid of the tachometer I am using to gauge speed. It was made in the early 60's and is 100 times more reliable than my fancy digital tach. Plus I love using mechanical devices.

I have it set on 3000-30,00RPM, so read the outer scale. It approaches 9000 RPM, but I can;t get it to stay there quite yet. Plus it is hard to tune the high speed when your fiddling with a tach in one hand, revving the engine with the other, and with the aid of my teeth, I am holding the camera by the neckstrap, trying to keep it in frame :big:

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Kel

 

[kcmillin]

Here is the same vid from the last page. I figured I would post it again since it got buried on the last page.

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Kel

 

[kcmillin]

Here is the overflow tank in action.

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Kel

 

[Lakc]

Looks and sounds real good! I made a 280 cam and forgot to take into account the lash, so the final duration and overlap were less then expected. Moral of the story is have fun making a bigger cam. ;D

 

[GailInNM]

Just great Kel. It gets better every time I look at it.
Gail in NM