I have several LA .40's and they are all the same.  Now I may have to tear one down to see if they are two port or three port.   

The three port engines are a little more powerful and a lot more "finicky" to get a "stunt run from.  They can run OK but in my opinion need to use a slightly smaller venturi (about .250 with the OS needle or .260 with a ST needle).   Smallish flatter pitch props help also to allow higher RPM "Wet Two" type runs that seem to be a little more consistent.

Randy Cuberly

Guy's ,  i am totally confused by this post. All 3 of my La 40's run great stunt runs. I have never looked to see how many ports they have, i didn't know there was a difference. As long as they run as good as they do i will not look at the ports or doubt them!!! I have bought them at an r/c swap meet new for $10 bucks. IMHO the la 40 is a great low cost stunt engine.

It's been my experience that the three port versions were only the earliest versions and all R/C types with Carbs.
As mentioned above it's very easy to look into the exhaust port and see the third port.   If it's there it's directly across from the exhaust port.
However if the engine runs to your liking I wouldn't worry about it.
If the engine is a CL version I seriously doubt that it's a three port...I've never seen one that started life as a CL (S) engine!

Randy Cuberly

Barely off topic: I'm setting one up to put in a Brodak Mustang to give to a friend who is trying to advance from beginner to intermediate. Planning on using an APC 10.5x4.5 prop. That sound about right?  Thanks.

Thanks, that's just the direction I was going. I think this is a 2 port so I may be in luck.

           Like I stated above, I took mine out of the box and bolted it on using the APC 10.5 x 4.5. I love it. I think the Randy Smith tongue muffler has a lot to do with the runs I achieve. I open the stock holes in his mufflers to 3/32" and I don't add any additional holes. I never checked the venturi as it's the one it came with. The plane would barely make the pattern on 4 oz. Sometimes I would have to run a bit leaner to get the mileage to make the pattern as the engine was starting to lean out in the overhead, barely making  the clover leaf. The Powermaster fuel seems to be the other key as the 11/22 works quite well in these engines. I've since added a 4 1/2 oz. tank and enjoying every bit of it. Ken

Hello Ray and Ken,
Thanks for the advice on the LA40, next time I give my sole example a try, I will take heed of your advice. I must admit I gave up with mine as it was very fussy about needling and it did give me some aggro as a result. I have tried the APC 10.5x4.5 and it didn't help much, so it looks as though the fuel and tongue muffler may be the key. Ray I did use the standard muffler and it didn't give me much joy, so maybe back to fuel as a cause.
Isn't it strange that an engine can get different reputations in different countries! Most folk in the UK sem to have a down on the 40 and love the 46! for stunt. The flip side is that the 40's tend to be very cheap over here, so maybe it is worth persevering a little more.

Thanks to you both,

Andrew.