DA 70 question
 

Hi Guys
I purchased a DA 70 this past summer and installed it in a Hoseteler plans RV4. It's a 35% airplane that I built. Ok the engine started the first time I tried it, and I have approx.
6 flights on it at this point. It idles beautifully, and has a nice, smooth tranisition to full power. The one problem that I keep having is that when I go inverted with the plane, it dies
immediately. I have a Rotoflow 24oz. tank with a 1oz. fuel accumulator/filter installed for the fuel system. Now tonight, I opened the cowl to check the high and low needle valves,and to see if their turns out from the body, match what the manual recommends, which is 1 1/4 for both... as a starting point. ok the low was about 1 1//2, and the high is only 1/2 half turn out. This is how it came from the factory. What I want to try is to invert it securely on a bench, open both valves to 1 1/4, then start it to see how it will run. I think the tank is good, because I did test the rotating clunk, before installing it. Does anyone have experience with this engine similar to this? If so any tips or help would be greatly appreciated. Thanks, Bob

What amazes me is that you have 6 flights on it as it came from the factory. The factory did not have your prop, your temp, your barometric pressure, your oil and gas mixture.

Why not tune the engine ?

Follow the stickies and tune would be my first suggestion.

I agree completely with kmeyers, tune the engine which means adjust both needles for operation with your fuel system, your fuel and your geographic location, your airframe and prop. Factory setting were good in Arizona on a test bench. That doesn't mean they are right for your situation.

If after doing a complete tune and if you still have problems, the problem may be airflow related which is very common for gas engines. Airflow can create different pressures in the cowl from upright flight to inverted that can affect the regulator diaphragm in the carb. There are fixes for this problem but I wouldn't address them until after you do a retune of the engine.

ok i'll try

got the plane on a custom test stand today, inverted it, opened the high speed to 1 1/2 , and started it right up. Ran most of the tank through.
I guess I should'nt have assumed that the carbs needle valves were set correctly from the factory.:rolleyes:

You assume correctly. The factory has no way of duplicating your exact airplane setup and location. You must always tune these engines for your conditions, prop, etc.