1. what is the point of the wall on the pistion, i know it has something to do with the air intake but does any one have a detailed description of how it works?

2. does the butterfly valve count as a muffler

3. where would i hook up the back pressure line from the fuel tank

thanks, dave trimmer

Edit: sorry that the dates are a little off

The baffle on top of the piston is to stop the incoming charge from scooting out the exhaust port. I'll leave your other questions to the RC fliers.

The exhaust baffle does not count as a muffler. It is useful to make the engine run better at idle but it does nothing to reduce the noise the engine makes. without a muffler, you don't have any easy way to pressurize the tank. So you just leave the second line of the tank open to the air.

The piston ridge helps determine the mixing flow inside the engine and control the flame pattern. You appear to have a K&B 40 there. The pictures ar so dark and blurred it's hard to tell much more. Based on K&B40's I owned in the past I'll say the following:

They used to put a rotary baffle in the exhaust port that closed off at low RPMs. One of the purposes was to keep up some backpressure at low RPMs to help keep the plug hot. An idlebar plug was often used also.
Back then muffler pressure often was not used and if it was it was tapped right at the exhaust port. There were some aftermarket mufflers for this engine that required removal of the baffle to install. I think Slimline made one.
http://www.mecoa.com/kb/index.htm for K&B information.

how would i attach a muffler? due to club rules.

The one I had required removing the baffle. The muffler was flat. It's height was the same as the exhaust flange and it's width the same as the exhaust. If I recall correctly it stuck out from the engine about 2 inches (approx). It was kept in alignment to the exhaust by 2 tabs, 1 at each end of the port that inserted into the port and also covered the holes left when the baffle was removed. A metal strap was then wrapped around the cylinder head and screw attached to each side of the muffler. Worked great.

Dave,

What you have is the old K&B Torpedo 40 with a Perry carb. In it's day it was a good, reliable engine and has the power of maybe an OS .32 today. Probably dates to the mid '70's. Here's a couple pics of mine that is for the time being retired. They clean up really nice if you want to display it. Mine is retired simply because it's worn out. I got a wild hair one day and completely disassembled it, chucked a buffing wheel in my mill and spent the next hour cleaning and buffing. Everything was buffed, including the piston, crank and rod - the inside looks like the outside does.

I used to fly it with a muffler (if that is what you could call it) that basically was an extruded rectangular straight exhaust with a spring inside to help create some back pressure. I think was a DuBro Silencer, but not sure as it's been around 35 years since I acquired mine, and it came with the engine. After a while I picked a Kavan strap-on muffler which is what you see in the pictures. It's big problem was the rear half would rotate on occasion and interfere with the radio until I drilled .

Does anybody have a new ring sitting around for a K&B Torpedo 40? I wouldn't mind getting this one running again and hanging it on a Kadet Mk I.

Hogflyer

http://www.mecoa.com/kb/index.htm
These guys should have it. Give them a call. The manufacture K&B today.

dave save yourself the headache and spend some $$ on a super tiger,or spend alittle more for a OS you won't be sorry.
ST are a solid inexpensive engine you will give yourself fits with the strap on muffler and tuning issues of a old and I will bet gummed up engine, when I started RC in about 1978 I had a K&B 35 engine it was a marginal at best motor and after about 1 1/2 flts. the muffler would loosen up on me it also would not run reliably it was a pain.
when I re-entered the hobby I swore I wouldn't get a inferior/inconsistant engine again BTW that engine was the cause of a spectacular crash after I donated it to a buddy for one of his planes right around 1981 fortunately we are still friends.

The wall is called a baffle and if you look at the transfer ports you'll see they're just square holes without any angles. The mixture comes straight in through those ports and the baffle turns them up towards the cylinder head instead of just going straight out through the exhaust. This is the way all engines used to do it except for diesels and the Cox engines. Nearly all engines now are Schneurle ported and they use angled ports to aim the mixture up towards the cylinder head which is why most engines have a flat top on the piston now. There are still some new engines made with that baffle though.

hogflyer
For a new ring contact Frank Bowman, a new one from him will be about $10.
[email protected]
1211 N. Allen Ave
Farmington, NM 87401-3568
503-327-0696

Nearly all engines now are Schneurle ported and they use angled ports to aim the mixture up towards the cylinder head which is why most engines have a flat top on the piston now

the above is not quite correct schneurle porting has ports on three sides of the cylinder,front,rear and opposite the exhaust.in the case of side exhaust engines.usuallt yhe timing of the engine allows thwe front and rear ports to open just slightly before the third boost port which keeps the charge from going out the exhaust and no need for the baffle.

thanks for the help guys, i want to get it running for my brother in law's step dad.

The 35 was never near the engine that the 40 was.

thats for sure! that thing was a dog it never ran the same from day to day and I ran many gal. of fuel through it, at the time I think it was enya that was the hot motor brand back then the deciding crash broke the case into several pieces it was awsome to watch untill we went over to check the pile of sticks that was my friends plane