Lil' Brother

[pkastagehand]

I looked through old messages and seen that other's have had problems getting this guy to run but couldn't find any details of what was done to correct problems or even what the specific problems are.

I have a Lil' Brother I made from castings purchased from Mr. Breisch in about 1976 or so. It is completed but I can't seem to make it run. I have had it run for several cycles before dying using the home-made points as described in the prints and a small 6v motorcycle coil. Then I came across the Jerry Howell sight and made one of those boards he designed for better spark. But right now I can't seem to even get it to fire. I don't know if it is electrical or fuel related. It has the original short reach plug that came with the castings/drawings. I'm wondering if a longer reach plug will help?

It seems to get fuel up there when I choke it so at least there is gas getting up which it would seem should make it pop now and then so that is why I'm thinking electrical at this point.

I've heard about someone altering the cam profile but can't remember how or who that was. Maybe a micro switch instead of my home-made points would be a more reliable make/break set up.

I've worked on full scale hit and miss (1-1/2 hp Economy up to a 7 hp Galloway) but this one is getting me down.

Anyway, I'm open to suggestions.

Thanks,

Paul

 

[gbritnell]

Paul, I don't want this to sound facetious but I'm sure you've checked the valve timing, the compression, the ignition timing etc. If all these are where they should be then the next thing is spark. If as you say you have no spark then I would resolve that issued first. Why don't you bench test the Howell ignition to see if in fact it's working. Hook everything up on the bench and just touch the point and ground wire together to simulate the points and you should get a spark. If not then you could go with a simple automotive coil, condensor and battery setup.
I don't know if it was my posting about changing the cam design but I did in fact do that to my engine. I didn't change the exhaust valve timing but rather the amount of time the points were closed (dwell) because it was longer than necessary. My Little Brother runs fine. Everything except the cam was built to print. I do have a longer plug in it but it didn't start out that way.
Here's a link to my engine.
[ame]http://youtu.be/U56CU_o5LyQ[/ame]
gbritnell

 

[pkastagehand]

The Howell ignition works in bench tests. I just wasn't sure if it was always working with my points.

How much compression is a minimum that will still run? It doesn't have a lot of compression so maybe that is the problem. The only way I had it running is with an o-ring on the piston once, but that couldn't take the heat/friction and started gumming up or binding. Maybe if I used a viton ring?

They man that got me started on hit and miss engines back in the 70s (he's now passed on) had a collection of most of the Sandwich engines made in Sandwich IL. His biggest was the 8 HP. He took the governor springs off or put really light ones on and had it set up so the flywheels would essentially stop at the point of firing.

Paul

 

[gbritnell]

Hi Paul,
As I recall Paul Briesch didn't call for any type of ring on the piston, just oil grooves. I have cast iron rings on my piston and it has very good compression. About the only way you can measure compression is to spin the flywheels and if the rod bounces back when it comes up on compression you have enough. Some fellows use O rings with good luck, personally I have never used them.
gbritnell

 

[rickhann]

Paul, I recently completed (sans paint) and I experienced troubles similar to yours. I would get a pop or two, then nothing. However I noticed that when fiddling with the plug wire, whenever I would remove the wire and there would be a spark between the connector and the plug it would fire. I googled spark intensifier and found an article on the Meissner spark intensifier. I built one in miniature out of a piece of 1/4 inch gauge glass and a couple of pointed screws, installed it and it was an instant success! I am not an electronic expert, so I cannot explain how it works (The Meissner article does), but it sure worked for me. One other thing, my first cam was not very good, so I had to make another one. I used o-rings as the compression was too low without some sort of a seal. Fuel mixture did not seem to matter much. I just used straight Coleman fuel. When the engine is cold, it does have a tendency for condensation to build up and foul the plug. Just my experience with my Lil Brother. Rick

 

[pkastagehand]

Hi Paul,
As I recall Paul Briesch didn't call for any type of ring on the piston, just oil grooves. I have cast iron rings on my piston and it has very good compression. About the only way you can measure compression is to spin the flywheels and if the rod bounces back when it comes up on compression you have enough. Some fellows use O rings with good luck, personally I have never used them.
gbritnell

Depending of course on how hard I spin the flywheels I get some bounce; spin it hard enough it goes past TDC which is of course how one starts it. I just don't have a "benchmark" for what it should feel like since my experience is with the 1:1 scale sizes.

I remade my piston to a tighter tolerance a while back which helped. The first piston had almost no compression without the o-ring. I am feeling like it just isn't enough spark so I think I will investigate how to intensify that. Possibly my batter/coil combination is not the best. Maybe need a different coil or if I keep the coil maybe a bigger battery?

Paul

 

[pkastagehand]

... I googled spark intensifier and found an article on the Meissner spark intensifier. I built one in miniature out of a piece of 1/4 inch gauge glass and a couple of pointed screws, installed it and it was an instant success!...

I actually saw that in searching old posts. How did you secure the screws in the glass? Epoxy? Or just sort of loosely thread them into the ends? It would be an interesting experiment and if it helps fire it would confirm my weak spark theory.

Paul

 

[Jadecy]

If you have spark and fuels it should pop. You don't need much compression at all. I'm using o-rings as rings and when you turn it over slow it does not have much compression. I use white gas in my little brother (Coleman lantern fuel). I did replace my plug when I was at NAMES this year with an imported plug from S&S and it ran much better. I'm using a 6v battery from the home store and a canister type ignition coil from the auto parts store.

Have you tried giving a shot of carb cleaner to see if you can get it to run a little? proper fuel delivery is very important. Can you post a picture of your engine and some close up photos of your carb and points?

Mine is running all parts made to the plans.

 

[rickhann]

Paul, I just turned down the nuts for 2-56 brass screws and epoxied them into each end of the glass tube. Screwed two pointed end brass screw in each end. This allows for adjustability of the spark gap. I don't think fine adjustment is too critical as long as the spark jumps the gap. My ignition system consists of a 6 volt battery and a 6 volt automotive coil. Good luck. Rick

 

[gbritnell]

Paul,
A spark intensifier is a gadget that allows the voltage to build up higher before jumping the gap on first the intensifier and secondly on the spark plug. That said, if your ignition system isn't strong enough to do this then the 'intensifier' won't help. If your ignition system is strong enough to jump both of these gaps then there is nothing wrong with your system to begin with.
The original use was to help overcome carbon fouled spark plugs. Carbon is a conductor so as the plug gets fouled with it the voltage tends to bleed off a little before the spark occurs. If enough voltage is bled off then possibly no spark will occur.
Unless your plug is very carbon fouled (unburned hydrocarbons) then there is no need to go this route except for the novelty of it.
I'm not meaning to step on anyone's toes about this but the 'intensifier' doesn't do anything that wasn't there first, namely good spark.
One of the first things I would do is to make a longer spark plug, one that will get down into the spark port that comes from the combustion chamber.
gbritnell

 

[Gordon]

My experience, gained from doing things wrong, is that the most common cause of non starting is low compression. I have used O rings successfully on several engines which makes the piston fit less critical. The next thing which I have done is I have made a box with a 6 volt gel battery like used in an emergency light, a 6 volt automotive coil and an automotive capacitor. I know this works on other engines so it eliminates the ignition uncertainty. Once everything is working I can go back an make a dedicated ignition system if desired.

Good luck.