So now I post my engine questions here, there seems to have been a transfer in knowledge!

I just picked up the above engine for a song. When putting it on the test stand, I was looking for the tank pressure nipple off the exhaust...! There isn't. I got confused!

I have searched, but haven't found a whole lot. I understand that the fuel draw from the carb alone is sufficient (due to the smaller carb). Is that true?

If so, then I just use one tube from the clunk in the tank? No other line open? If so wouldn't a vaccum develop that would, as the fuel is used, make it harder to draw fuel?

Would it make more sense to drill and tap a hole from the muffler?

Performance isn't required from this engine. I plan on using it on a mini pizza SPAD, it won't be flown far away as I understand that the glide as well as a brick.

Thanks for your help!

Most engines of that time period, did not have a muffler tap on them. You had to drill and tap a hole and put one in yourself. Heck they still sell some new engines today without a muffler vent tap on them.
Generally everyone ran a muffler tap as soon as the first guy showed up at the flying field with one and tnhey saw how well it worked. It sure made setting the needle valve less tricky.

You always have a vent on the fuel tank. You would just put on a short piece of tubing or bend the vent tube so that it's tip was up above the fuel tank top. if you had it in the prop slipstream, you would cut a angle in the vent tip angled forward to get a little pressure off the air slipstream. One company used to sell cute little plastic air scoops that one could use too.

Adjusting the engine's needle meant the engine without muffler pressure means you tended to run a little more rich when the tank was full and maybe a little bit lean when near empty. But when half full you were usually right on for the needle setting. You could almost tell when you were getting low in fuel by how well the engine was running then. of course fuel tank position was more critical, but back then the airplanes had larger noses on them, so you could mount the fuel tank higher inside.

I am embarrased to say, but I have four of those K&B 20 engines myself. They are leftover from a ill fated B17 I was trying to build. The plane got crushed in the storage shed one day by some stuff that fell on it. I have been thinking about using them on something ever since then.

Thanks, a trip to Mikes is on the to do list tomorrow then! See if I can get one of the guys to drill and tap the hole for me as well. (I don't have a tap set!)

I have one of these engines. The muffler has two main parts. The cylindrical (business) part and an adapter that fits between the muffler and engine. The adapter is the part that has the fuel pressure nipple. Mine is screwed into the underside of the adapter.

By the way, you can still get parts for this engine at www.mecoa.com

That is a good point. Do you have the short extension that goes between the cylindrical muffler and the engine?

Evening all.

Yep, I have the "extension" and the cylindrical muffler. There was no nipple (sorry, I just like saying that word - and no, i'm not 12!) on the extension.

There is now, $1.90 + tax + a very nice Mike at Mikes!

I haven't spun it up to see the difference as that nipple (there we go again!) interferes with the bolt on the engine test stand...

However, I do have the pizza box SPAD mostly together. I need to loosen up the hinges.

I did do a very dumb thing. I divided the back into two, to make elevons. I then proceded to put one servo on and put the control rods on like ailerons..... So now there's two servos and i'm just about to add the throttle servo. May maiden it tomorrow afternoon!!

I have three of these engines, two .20's and a .28, they do not need muffler pressure. I added a pressure nipple to one of the .20s and it did not improve the handling of the engine one bit. Just keep the fuel tank as close to the engine as possible and try to keep the center line of the tank at the level of the needle valve. None of mine have the remote mounted needle valve so I can't comment on that.......... RJ

Using elevons on the PBF planes is very common. No big deal. Most all of my fan fold foam planes are elevon types.

It's no big deal if you think it through, but I just shoved one servo on, put the control rods on and thought, oh.....!

I'm with RJConnet on this one. I have a number of K&B Sportsters and they run just fine without muffler pressure, but there are cases where pressure can help. Like RJConnet stated, if the tank is positioned in a reasonable fashion, they run fine without pressure. I had one aircraft where I needed to position the tank a bit further aft. I ran pressure on that one and it was a happy camper. The needle valve was a bit more sensitive, but very consistent.