Ford GAV

Discussion area for builders of Pietenpol aircraft, both beginners and experienced folks. Share ideas, ask questions and help build the Pietenpol community.
Post Reply
donbrewer
Posts: 15
Joined: Sat May 27, 2017 2:36 pm

Ford GAV

Post by donbrewer »

This question is for those members who are running a Ford engine in their Piet. What have you done with the GAV? I have mine operating, with a motor-tool cable reversed around the front of the engine and a rotatable knob on the instrument panel. It works fine but I'm having a hard time with a hot start,, I have not figured out the hot start procedure. I'm wondering what position the GAV should be. Cold start is two turns rich and pull the prop thru four blades with choke and it usually starts on the first pull. Hot start is not easy. My idle rpm is smooth at 700 and above but erratic below. Does anybody have any suggestions? Don
Last edited by donbrewer on Fri Mar 27, 2020 12:19 am, edited 1 time in total.

JCB
Posts: 6
Joined: Sun Feb 26, 2017 11:16 pm
Location: La Conner, WA

Re: Ford GAV

Post by JCB »

I have also wondered about this. In a model A car I noticed that using a Grose Jet substantially improved the carb. With a Grose Jet, I have observed that the gas adjustment valve can usually be set once and ignored. I am still building my Piet. I have a model A engine and a model B engine on test stands. Both with Grose Jets. I am hoping that I will be able to set the gas adjustment valve and not need to adjust it. I plan to get the engines running on their test stands this summer and I'm sure I'll learn a lot.
Attachments
IMG_6409 copy.jpg

User avatar
taildrags
Posts: 312
Joined: Tue Mar 07, 2017 10:39 pm

Re: Ford GAV

Post by taildrags »

JCB: that's a very sanitary test stand setup. Nice! What are you driving on the output end of the crank? Is that a hydraulic pump or something that you can use as a variable load dyno?

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power

User avatar
Richard Roller
Posts: 62
Joined: Mon May 22, 2017 11:14 am
Location: Olathe, Ks.

Re: Ford GAV

Post by Richard Roller »

On Ken Perkins Piet the GAV is safety wired in one position. We've never had a problem with having to adjust it. Ken just messed with it until he was satisfied with the idle and the pick up coming off idle. It can be slightly rich on a hot day, until you come off idle. If you think about that, it's not really a problem, aircraft carbs are set up rich at idle, it prevent a possible lean situation during a long throttle closed decent.

JCB
Posts: 6
Joined: Sun Feb 26, 2017 11:16 pm
Location: La Conner, WA

Re: Ford GAV

Post by JCB »

Oscar, My test stands are raised up about 6" to let my engine hoist slide under the test stand. The test stands allow 2 ways to mount the engine. Today a Model A Bell Housing is used to mount one end of the block and 2 supports mount the cam gear end of the block. The test stand also allows the engine to be mounted using standard Pietenpol mounts. Today there is a flywheel with a ring gear on the crank. None of the clutch parts are there. I use a High-Torque starter from Summit Racing. No Dyno on the test stand. I built the stands so I could run in the engines and work out a bunch of fire wall forward issues including :

Do I need to adjust the Gas Adjustment Valve ?
Is there a better way to connect the gas line to the Model B Carb ?
What would it weigh to add an electric starter ?
What is the best oil filter solution and what does that weigh ?
How to mount a generator and what would that weigh ?
I plan to use my Model B engine. What does it weigh vs my Model A engine ?
I have 2 Model B crankshafts... one balanced without counterweights and one balanced with counterweights. It is tempting to use the lighter one without counterweights, but I want to test it both ways.
Which magnetos do I like best ? I am testing Slick, Wico Jet, Wico X, and Pertex. I would like to try a Bendix.
What is the right timing of the 2 magnetos ? Should one fire 2 degrees before the other one ? Or What ?
How to smooth out the vibrations as much as possible ?
How to design the Radiator ? I built the front 16" of the fuselage on the test stand and the leading edge of the wing to help me design a radiator similar to Dan Helsper's that will fit my airplane... get the right angles on the inlet/outlets and get the mounting methods worked out. Should the Center Section be modified for a better radiator mount ?

The stands allow me to build and use the normal Pietenpol engine mounts... with or without the Bell Housing in place. I will build the Piet engine mounts on the test stand and run the engine in the Piet engine mounts... working out the throttle, choke, and other gauges and controls. I would rather try things on my test stands than on my Piet.

Lots to learn.

None of those questions need a Dyno. What are the questions that require a Dyno ?
I have read the Dallas Model A dyno tests at http://www.modelaparts.net/dynosheets.h ... heets.html We have 3 Dynos in my neighborhood. 2 are drive on setups. I could put an engine in one of my model A's and use one of the drive on dynos.... or there is a small engine dyno from Power Test Inc. Similar to the one that the Dallas guys used. I could go mount the engines on that dyno. Lots of work so I need to understand what we need to know that the Dallas guys have not already answered.

John

Post Reply