Horizontal Air Cooled Engine

[Gordon]

Gordon---the flange on the valve guide is there because---I have this terrible fear that without a flange, the Loctiite would heat up from the engine running, and as I hover over the engine running it, the engine will fire and shoot valve guide with valve attached out and hit me in the eye. Shopshoe---These piloted counterbores and different size pilots are readily available from toolshop suppliers.---Brian

You could accomplish that even if the counterbore was a few thousands oversize.

 

[Brian Rupnow]

HURAYYYY-My sparkplugs came in the mail today from Steve Huck--And what beautiful sparkplugs they are!!! I had only ordered one with a 5/16"-24 thread, because I buggered up the threads for 1/4"-32 in my aluminum cylinder head. There was too much work in that cylinder head for me to scrap it, so I decided to go up to the next larger thread size and re-tap it. Steve has sent me what I needed and also samples of his "standard" plug with a 1/4"-32 thread on them to show me the quality of his work. I think the quality is excellent, and Steve's business card is in the picture for anyone who wants to order spark plugs for their project. Thank You Steve Huck!!---Brian Rupnow

 

[Brian Rupnow]

And here we are, head rethreaded and new sparkplug installed. Engine build can now resume.

 

[CFLBob]

Yay!!

 

[Brian Rupnow]

Thrilled to announce that the engine is back together, valves and pushrods are installed, head and head gasket are installed, and flywheels do seem to have "bounce back" when given a flick by hand (which is a sure sign of compression). Valve timing and valve gap (between pushrods and shcs has not been set yet. I don't need the fan housing and fan on there yet. Also still have to make a gasket to fit between intake manifold and cylinder head. Tomorrow---tomorrow---

 

[awake]

Can't wait to hear it run!

 

[Brian Rupnow]

Everything is buttoned up and I am just at the point of setting the valve timing with a degree wheel. You can see that I have a pointer attached to the crankshaft, and by loosening the set screws on the small crankshaft gear and loosening the set screws on the intake cam, I am able to move things around until the intake and exhaust valve begin to open at the correct time in the cycle. This particular degree wheel was originally designed for a vertical cylinder engine. It still works for me here, even though the "0" degree marker is at the top of the dial.

 

[Gordon]

Brian: I have a question for you. If I have read your posts correctly you obtain final cylinder bore size by drilling and reaming and then finishing with a brake hone. Is that correct? I have tried a reamer for final bore size and I have not had good results. My understanding is that if the drilled hole is not perfectly round the reamer will follow the egg shaped hole.

 

[Brian Rupnow]

I've never had issues with a reamer. As long as the drill is at least 0.020" smaller than the reamer. The reamer will make an oval hole become round. But--If you drill wanders a bit, the reamer will follow it.

 

[Brian Rupnow]

Yesterday afternoon I tried everything I can think of to start the engine. Not happening. Valves lash and valve timing is set "by the book" and ignition timing is correct. Tried a fresh can of fuel, made no difference. After about 4 hours messing with things, I thought "Everything is set perfectly but the engine won't fire.--Maybe it's my new cast iron rings." I squirted 30 weight oil down the sparkplug hole, and compression rose a great deal---that must be it---my c.i. rings are no good. So---today I made a new piston and put a Viton ring on it. Changed pistons about half an hour ago---and---it didn't make any difference. Engine refuses to fire with cast iron rings and with Viton ring. Sparkplug from Steve Huck is firing fine when removed from sparkplug hole and laid out on top of the cylinder head. But when cranking it over, not a pop, not a fart----nothing. I haven't seen an engine act like this before. Both intake and exhaust valves are sealing very well. If I choke it with my finger over the carb air intake while cranking it over with my electric drill, it will pull fuel up from the tank, and spit it out the exhaust pipe. But not firing at all. Thinking---thinking---

 

[Brian Rupnow]

Before I take anything apart, or change any settings, there is one more thing I will try. That is to try using automotive gasoline instead of Coleman fuel. I'm not sure why that sometimes works, and it probably has to do with the volatility of automotive gasoline. This gets a bit too scary for me to do on my side-desk in my office. Tomorrow I will move operations out to my main garage, where there is more of a chance to put out any catastrophic unexpected fire disasters.

 

[johwen]

What I have noticed Brian is on your degree wheel Your pointer is not parallel with the degree line emanating from the centre and is at considerable angle. This would throw the valve and ignition timing way off. Looks from the photo to be way of by as much as 25 degrees. Correct me if I'm wrong.
John

 

[Brian Rupnow]

Jonwen--The pointer wasn't pointing at anything in particular during that shot. That was simply a picture of the degree plate.---Brian

 

[dsage]

Try starting fluid with no liquid fuel. That will eliminate issues with the engine possibly flooding or starving.
Also
If the plug fires properly (across the gap) when it's out of the cylinder, put the plug in the cylinder and put a spark gap in line with the plug wire. If you get a spark at the gap it will also be firing at the plug in the cylinder. It's unlikely but compression might be high enough (or your spark too weak) to fire under compression.

 

[Brian Rupnow]

Yesterday was a complete write off, machine wise. Spent half the day designing something for a customer and half the day doing pre-Christmas things. Today however, I got really bold and tried to start the engine with automotive gasoline in the tank. No difference at all!! Engine will not fire. It is definitely sucking gas up to carburetor but not igniting it in the cylinder. Engine has good compression. Even if timing is out of whack, I should be getting some pops and farts while turning engine over with drill, but it's not happening. Can it possibly be the sparkplugs?---surely not. Steve Huck sent me two new sparkplugs and they both fire like crazy when laying out on the cylinder body. It has to be something deeper. I will now pull the cylinder head off and see if something is funky with the head gasket.

 

[Brian Rupnow]

Okay---Just pulled the head off. This is a view of the inside of the cylinder head. There was nothing funky about the head gasket. There was nothing funky about the position of the sparkplug relative to the valves. The only thing I can see is that the spark from the center electrode to the side of the plug is happening on the side away from the valves. If I put a small brass washer between the sparkplug and the cylinder head, I hope to be able to re-tighten the sparkplug and have it so that the spark jumps to the valve side of the sparkplug. It seems highly improbable that this would cause a "no fire" situation, but when everything else has been checked, we start to seek out the improbable and correct it.

 

[johwen]

Hi Brian, If you crank over the engine with your drill and then pull the plug out is it wet with fuel. If it is it has to be ignition. Is the spark blue or yellow? Yellow being not very hot and under compression not firing. John

 

[Brian Rupnow]

Jonwen--I'm not coordinated enough to take a picture of the spark the same time it is happening. However, it is a good spark, not weak at all.---Brian

 

[Brian Rupnow]

YES!!!!--That did it. Engine is now finally firing. Turning the sparkplug 180 degrees so that the spark was occurring closest to the valves done the trick.---I'm happy--happy--happy. Next amazing stunt will be getting an extended run and making a video.

 

[Gordon]

Since the only real difference in this engine over others is the spark plug I would think that is the most likely problem. Perhaps the arc is following down the outside of the plug or jumping from the cap to the head or some other metal part like. I have had that problem and I had one engine which would only run with a longer plug.