Avro Anson C19 / Cheetah Fuel Circuit

Don’t think it would be to directly pressurise the priming circuit instead of the Ki – Gass, because of the lack of control. Its a small pump but it moves a significant volume. The Anson operating manual gives the required number of pumps on the Ki – Gass required dependant upon the ambient temperature when starting, which I doubt you would control with the electric pump alone.

Actually this is something that is not as big a problem as you might think. On many fuel injected engines you prime the engine using the fuel pump (electric) and then shut off the fuel pump and close the mixture again. This way the engine is basically flooded, but as you crank the engine and air is drawn through it the mixture progressively leans until it reaches its optimum point at which the engine fires. You then open the mixture to keep it running. I’m sure I’ve read about this same technique being used on radials (I’ve only used it on flat-fours and -sixes). On fuel injected Pipers with the optional priming system installed there is a graph in the manual that also uses ambient temperature and gives you the number of seconds that you need to prime, quite similar to the number of pump strokes in your paperwork.

It’s all gone too far. I don’t know of anyone who would, or could, be offended by the word c**k – unless you were one of those who wished to be so and would latch on to any old pretext.

Nuts, I say! – and worse for the fact that people in our society are prepared to indulge such idle pomposity.

Great work by the way, AGPGPORT. I’ve seen your labours’ where others here haven’t. Little do they know, now, of the treat you have in store for them when you unveil your stunning project;-)

Anon.

It appears that the Standard word for ” a male chicken” is not allowed on the forum. It is the correct term but in future I will write hand valve.

Amused Dave

Hi Mike, Thanks for the response. Don’t think it would be to directly pressurise the priming circuit instead of the Ki – Gass, because of the lack of control. Its a small pump but it moves a significant volume. The Anson operating manual gives the required number of pumps on the Ki – Gass required dependant upon the ambient temperature when starting, which I doubt you would control with the electric pump alone.

The best explanation to date from my performance car knowledgeable friend, (Wilky) is as follows:-

“On racing cars the electric fuel pump of this sort would be started, prior to trying to start the engine,to ensure sufficient fuel at the carb/injector as soon as you turn the engine over ie not turn it over and wait for a few turns for the float chamber/fuel line to be filled sufficiently by the engine driven mechanical pumps. I can imagine that if the electric pump was configured to do such then the fuel would get to the ports in a timely manner.Once the engine fires and runs smoothly the electric pump is turned off”.

I have found out since posting the thread that the small side connection above the filter on the picture does in fact go to the priming circuit, so the leg of this circuit up to the priming **** before the Ki-Gass primer would also be pressurised.

The mod did not appear on G-AGPG but I’m going to incorporate it anyway. There is very little head above the Mechanical fuel pump level, because of the location of my fuel tank, so any advantage I can get for starting will be good.

The added benefit, When seen by the knowledgeable contingent at shows, (sometime in the future ), they will be able to acclaim loudly ” hey that wasn’t fitted to Aggie paggie. I can then respond accordingly, Suggestions appreciated.

Regards
Dave

Is it a mod for electric fuel priming in lieu of the hand (Ki-Gass) pump?

Anon.