Electric Primers

I have just installed a electric primer on my 0-360. What I notice is that very little fuel comes out the nozzle. I was expecting a much better flow of fuel. Can anyone help me out. I did notice that thier seems to be restricters in the fittings. I put the Steel fittings in at the cylinders their were no restrictors in these, and the other three fittings aluminum with red paint at the solenoid valve and out of the top of the gasolator.

Jim


UPDATE
I talk to Van's today and they had a shipping error and sent me fittings that were to be used for a manifold gauge. So that is why they were restricted. New ones on the way.

fuel priming

I don't know because the guys at Van's talked me out of a fuel priming system, and rightly so. If your O-360 is carbureted, you can give the throttle one stroke and then wait for 30 seconds or so for the gasoline to vaporize in the carburetor before cranking the engine. That along with engine preheating should get it started without any problem. It has worked for me at temps down to +5F.

Since the priming system puts fuel in right at the intake, it shouldn't take much to get the job done?

There is a real difference between putting excess fuel into the carb via pumping the throttle and using a primer system which sprays the fuel into the intake passage on the cylinder.

The primer system should work much better, and should greatly reduce the possibility of a fire following over-priming. I've seen the result of over-priming fires, and they can be ugly. Fortunately, I've only seen over-priming fires from the outside of an aircraft, not the inside. Unfortunately, one of the incidents was an aircraft I owned in a partnership!

That said, I installed a primer system when I built my RV-6, but I never figured out how long to hold the primer switch (didn't want to over-prime), so I was never happy with it. In addition, it added failure points and (I believe) conducted heat into the gascolator, aggravating vapor lock problems. A couple of years ago, I removed the priming system and have been using the accelerator pump to prime since then.

What works for me is to turn the master on, set the mixture to rich, pump the throttle once, wait a few seconds then turn the engine over for 4 blades or so to draw the mixture into the cylinders. After that, I go mag's hot, hit the starter again, and it starts very well.

That said, the best thing I've done for cold starting is to add a sump heater and a timer to control it. Even on a cold (OK, cold for Georgia) morning, the engine turns right over if I've used the sump heater, and I don't have to fast idle 10 minutes to get the oil temps up before I go flying.

At the risk of getting flamed....

OK, I also use the accelerator pump as a primer, but I was taught not to give it a pump until you are cranking the engine. This way, you actually are drawing a suction through the carb, and the excess fuel is pulled directly into the cylinders, never allowing a pool of fuel to develop in the induction system. I personally would be scared to let gas puddle in the bottom of my air box, but I may just be scared of nothing.

I have used this method of starting for at least 15 yeasr on my big-engined AA1, and it always gave me a quick start, even in cold weather - just took an extra pump or so. So far, the technique has been golden on my new -8 as well. I did install an electric primer solenoid, but have yet to use it - we just don't get that cold in south Texas!

Paul

Priming........

Years ago when I started crop-dusting in a back-pack Super Cub, my boss showed me how to correctly "prop" an engine. I had opened the throttle too far and didn't have enough velocity in the intake airstream to pull the fuel mixture up into the engine. He said "Close it up more, Smitty" and I did. He said that when you hear it "sucking", it's just right. Later, I stood outside the airplane and rocked the prop and you sure can hear a sucking sound if the throttle is barely cracked......about 1/8th to 1/4 inch in the cockpit. Any more open and you won't hear it sucking....try it!
Pierre Smith RV6A 17hours TTSNEW luvin' it too!

My Proc.

One stroke of the throttle with mixture full rich and prop max rpm. Aux. fuel pump on. Push and hold primer solenoid switch for 5 seconds. Turn key to start - Vrooom. When it is hot, like after refueling, just put throttle to start position no pump or prime.

O-360-A1A. Right or wrong it works for me.

Bob Axsom

I also have one of Van's electric primers. I have always been a little nervous about the "pump the throttle" method of priming because of the potential for getting excess fuel in the intake and having a backfire cause a fire. Here in Alaska this is fairly common. Similarly, I've been nervous about the electric primer since you don't have any way to tell how much fuel you're actually getting when you engage the electric primer. So what I've been doing is simply start cranking, no throttle pumping, no priming. Then, while the engine is turning over, I push the electric primer button until the engine fires. I release the primer button as soon as the engine is running. I assume I'm getting just enough, but not too much, fuel this way. This does result in the engine turning over a little longer than it would if you got the pre-cranking priming "just right", but it seems safer to me.

John Miller
RV-8A, O-360-A1A, carb, mags