Well, it's running better now, but not totally fixed. The sensitivity to fast rolls turned out to be a clunk issue; thin wall black tubing was actually too flexible and kinking.

The engine still quits eventually, after around 10 mins of air time. I'm wondering if fuel foaming is ever a possibility with gasoline engines?

Did one on a DL-50 soldered then ran back just behind the fuel tank, used a pill bottle and drilled holes in it through out.

I think all you need is one 1/16 inch hole in the bottle. Not sure????? Capt,n

Originally Posted by Low_Cal

Well, it's running better now, but not totally fixed. The sensitivity to fast rolls turned out to be a clunk issue; thin wall black tubing was actually too flexible and kinking.

The engine still quits eventually, after around 10 mins of air time. I'm wondering if fuel foaming is ever a possibility with gasoline engines?

Do you use a felt clunk and three line system?
felt clunks are soaked with fuel, and do not react to fuel foaming. As long as the felt is wet, no air will be drawn by the carb.

BTW,
Static tubes and static ports are one step better than the pill box. The pill box (with very small hole) will use airpressure from inside the fuselage, which is by no means constant. Using one small hole will avoid sudden reference pressure changes.
The static tube however senses the outside air pressure, which is constant. So do static ports.

Pe, I have been using a white "ceramic" pickup, I think it's actually made of a porous plastic. Do you think a felt clunk would be better than that? For the next attempt, I've installed a slightly smaller tank that allows more room for padding. All in all, it is working very well now, no stumbling during manuevers, but sometimes it just dies flying straight and level for no apparent reason. This old BME engine is certainly a shaker.

Having tried every diaphram solution mentioned on this forum, I have to agree the static tube is by far the most effective.

Yes, I always use three line systems on all my planes.

sub

I have a DLE30 that has been giving me grief for quite some time now so I will definitely try the static source pitot tube and I will share my results. Thanks for all the good info!

change to the walbro felt clunks as pe mentions - they are great, they are filters, stops bubbles and will suck every last drop out the tank. Not that i have ever cut it that fine i would hope

Originally Posted by Low_Cal

Pe, I have been using a white "ceramic" pickup, I think it's actually made of a porous plastic. Do you think a felt clunk would be better than that? For the next attempt, I've installed a slightly smaller tank that allows more room for padding. All in all, it is working very well now, no stumbling during manuevers, but sometimes it just dies flying straight and level for no apparent reason. This old BME engine is certainly a shaker.

Having tried every diaphram solution mentioned on this forum, I have to agree the static tube is by far the most effective.

Yes, I always use three line systems on all my planes.

Originally Posted by Low_Cal

Pe, I have been using a white "ceramic" pickup, I think it's actually made of a porous plastic. Do you think a felt clunk would be better than that? For the next attempt, I've installed a slightly smaller tank that allows more room for padding. All in all, it is working very well now, no stumbling during manuevers, but sometimes it just dies flying straight and level for no apparent reason. This old BME engine is certainly a shaker.

Having tried every diaphram solution mentioned on this forum, I have to agree the static tube is by far the most effective.

Yes, I always use three line systems on all my planes.

There seems to be a felt clunk replacement: a new nonwoven plastic "sponge" materials that replaces the sintered plastic clunk which BTW is no good. Sintered plastic clunks clog quickly. This new material now is available in many garden appliance stores.
Felt clunks last quite long, but slowly shrink and become more dense. I wash out the felt on a yearly base, and never had to replace a filter shell yet.
Some say that the felt will shed fibers that can enter the carb suction line. But I never found felt fibers in my carb filter, so I consider such statements hogwash. It it does shed fibers, they never seem to make it through the rest of the filter material.

How do you distinguish the new plastic clunk from the old sintered type? I don't know which I have. Oh well, maybe I'll just see if I can get a felt clunk at the local lawnmower shop.

"Hogwash" , HA! Haven't heard that one in quite a few years!

My ZDZ80 runs rich in flight, in fact the mixture seems to vary depending on speed, attitude and so on. I have done more than 100 flights with a slightly spluttering engine at times which runs perferct on the ground. It never really bothered me as I had ample power for all the flying that I do. I would love a perfectly running engine in flight too, and have been reading all the posts on the various fixes for the changing pressure problem. Will try out the static tube and share results.

Well, flew three 20 min flights tonight, without a hitch! I twisted her tail hard, so I'm going to hasten to say she is fixed!

I had several problems besides the diaphram; the final fix was putting the tank on top of a solid inch of latex foam, and opening the high speed needle another 1/12 turn.

Thanks for everyones help!

Test flight tomorrow

Just got back from the field, very disappointed. The static tube didnt seem to work at all.
On the ground the engine runs fine, once airborne the engine begins to splutter and gets progressively worse until i finally have to land as power is very erratic and very low.
Picture in the prvious post shows my installation. Can anyone spot anything wrong with it?

I cannot see where the hole is in the side of your static tube. The hole should be located about halfway the pinched end and the bend.
The tube itself is located OK.