A new engine for fall---

[brian Rupnow]

Engine does have reasonable compression for a new engine that has never yet fired. I hooked it up with a v-belt to my 1800 rpm electric motor with a 1:2 ratio so it was turning at 900 rpm+/- for about 10 minutes without the sparkplug in it, to loosen it up a bit. I then put the sparkplug back in and turned the engine over with my variable speed drill. I had coated everything with oil, and as I turned it over, I seen ripples in the oil racing away from the sparkplug. Closer investigation shows that I need to machine the counterbore that the sparkplug sets in about .020" deeper to get below a cooling fin groove. That will be my first chore in the morning---Pull the head and machine the sparkplug seat a tiny bit to get a good seal at the plug. I will borrow a gas tank from one of my other engines.

[Willy]

As I began my final assembly of the engine, a thought occurred to me. The displacement of this engine is quite large in relation to the volume inside the crankcase. I am breaking new ground here (for me anyways) and I thought it MIGHT need a crankcase vent. It might not, too, but now is the time to put one in, while I can still pull the engine all apart and flush it out before I put the rod and piston back in. If I don't need one, that's fine, it won't do any harm and didn't cost any money. If it does need one, at least it's in there.----Brian

Very wise move Brian to allow for a crankcase vent.
Having the vent in will decrease parasitic pumping loses drastically. Without it you are essentially pressurizing the crankcase needlessly on every down stroke and creating a small vacuum on the piston's upstroke. It may seem trivial because the crankcase volume is so much larger than the combustion chamber but when the rpm's get into the hundreds that beautiful little engine of yours will run smoother and be happier.
Try it both ways, at least now you have the option.
Looking foreword to a successfull startup video soon!

[brian Rupnow]

It's been a GREAT morning here. I got up and borrowed the gas tank off my Odds and Ends hit and miss engine, did a little machining on the cylinder head sparkplug seat, hooked up the battery, and AWAY WE WENT!! I have lots of clean up and finessing to do, but we have a runner!!!!--Brian

https://www.youtube.com/watch?v=np2N5ZxtKuo&feature=youtu.be

[brian Rupnow]

As a matter of interest, I took my new laser aimed temperature sensing gun out to the garage after the engine had been running for 15 minutes at a mid range speed. The top of the cylinder head was 180 degrees F at the base of the cooling fins, and 150 degrees F at the tip of the fins. The exhaust pipe at 150 degrees half way down its length, but 195 degrees F right where it exits the engine.

[brian Rupnow]

Here is a video taken from the other side of the engine, and a video in which the Chuck Fellows carburetor gets an honourable mention. The crankcase vent doesn't seem to have any effect on the way the engine runs, whether it is open or blocked.

https://www.youtube.com/watch?v=D4w1-NEzby0&feature=youtu.be

https://www.youtube.com/watch?v=tJRQ2FaaMoM&feature=youtu.be

[RichR]

Hi Brian
Wow, that's running very nicely. I'm sure you noticed, but there's a nut that appears to be rotating on the tappet closest to the fuel tank.

[topct]

Hi Brian
Wow, that's running very nicely. I'm sure you noticed, but there's a nut that appears to be rotating on the tappet closest to the fuel tank.

That's actually what is supposed to happen. A properly ground camshaft has a very slight angle so that as contact is made with the lifter it causes it to spin. This spreads the wear around that face of the lifter. I notice the other lifter is too perfect. Not an issue for this kind of engine.

Well done Brian. Seems to not have needed a whole lot of fiddling to get it going.

I do have a comment about one feature. If the slot in the points plate were such that the tension bolt were also the handle used to move it, it would be easier to adjust the points timing.

[Willy]

...
..... The crankcase vent doesn't seem to have any effect on the way the engine runs, whether it is open or blocked.

Thanks for the update Brian, good to know. I would think that the crankcase volume is probably large enough to dissipate the change in volume as the piston ascends and descends in it's bore, this and the rpm may not be high enough for it to be a factor. At least you had all of the bases covered and now we all know.
Glad to see it spool up and run so nicely right off the bat.
You're starting to get good at this.

[Norman Bain]

Well done.

[sasquatch]

Agreed, sweet engine, and thanks for all the great interesting postings along the way.

[brian Rupnow]

Thank you guys. Sometime within the week, I will be posting a link to a download of all the updated drawings as .pdf files. Nothing would give me greater pleasure than to see someone else build my engine.---Brian

[Cuttings]

Great job Brian
Sounds good all the way to the other side of the country.
I particularly like the temperature reading you are getting.
In my opinion that is exactly where you would like it to run.

[brian Rupnow]

After I went to bed last night, I realized that during the excitement of the first run, I had forgotten to put gaskets between the intake/exhaust flanges and the valve body. The exhaust gasket is not terribly important, but without an intake gasket it's a wonder that the engine run at all. I will start today getting all of the drawings ready for download.

[brian Rupnow]

I have uploaded about 40 drawings to filefactory.com. If you click on the attached link, you should be able to download then free. They are in pdf format, so you won't need any engineering software to open them. Somebody please let me know if this works okay and lets you download them with no hassle. If anybody finds errors in the drawings, let me know about that please.---Brian

http://www.filefactory.com/file/1dkn3uxr9xbx/RUPNOW%20ENGINE-2.zip

[vpt]

Very nice Brian! That motor runs very well, well enough to be put to work!

Did you check to see if any pressure builds up in the crank case threw the vent?

I must have missed it, what sort of lube system do you have for the crank and rod and stuff?

I also noticed in the video you mentioned the entire engine is built from bar stock, then mention the cylinder is cast iron?

Again very nice job! I always enjoy seeing your build and then the videos!