GAV drifts open

T

TOMS

Junior Member
Is there an adjustment to add more rotary friction on the GAV? Mine has started to drift open while driving and is causing rich running. Today, the motor started skipping and all plugs were covered with black mossy looking carbon. Carb is late '31 side-bowl.

I appreciate the help.

Tom
 
I had the same problem on my 1931 coupe and the solution I arrived at (c 1975, so perhaps youth and inexperience will gain forgiveness) was to ever so slightly arc the choke/GAV rod such that it bore against the firewall grommet (not originally provided for the Model A) and the gas tank choke rod support ring grommet.

Not a very sophisticated approach and perhaps (more like "no doubt") others will have a better solution.

In the event, you might start with a new fuel adjusting needle and housing (depending on what type of carburetor you've got) or a new set of the above-mentioned grommets, in the hope that new rubber and (perhaps) a smaller opening will solve the problem. These seem to me (at my now-advanced-age) to be better things to try before "tweaking" the choke/GAV rod (no matter how slightly).

(Additionally, it sounds like you may have a bit more than normal vibration that's making the problem worse, so that might warrant looking into.)
 
My GAV tends to drift CW about a 1/4 turn to close by itself while driving; I typically have it set at about 1/2 open when driving. As I drive, it seems to rotate about 1/4 CW towards closing. Any ideas why this happens? Thanks.
 
If you pull the GAV appart, there is a small spring c clip near the bottom, around the outer sleeve. If this is broken, missing or lost its tension, there will be no friction on the shaft of the needle part of the GAV, allowing it to move where it wants.
 
dave in australia said:
If you pull the GAV appart, there is a small spring c clip near the bottom, around the outer sleeve. If this is broken, missing or lost its tension, there will be no friction on the shaft of the needle part of the GAV, allowing it to move where it wants.
Click to expand...

Years ago someone posted that Les Andrews' book suggested removing the spring steel "C" clip on repros because they were too tight. I don't own any of his books so I can't confirm such a bad suggestion. That may be what's contributing to all the problems recently surfacing.
 
I'm constantly checking my GAV while I drive anyway, to accommodate different driving conditions and changes in power, altitude, outside temperatures, and engine sound. I figure it's just part of driving an A. When I was young and single it was a good excuse to reach across a girl's lap. ;) Now it's just habit.
 
Put a spring clothespin on the rod, just behind the bracket on the gas tank.
I had a Marvel carb on my car for a while, and it had this problem with no way to fix it.
But my Zenith has the correct GAV needle assembly, and it has plenty of tension and does not drift.

Doug
 
Re: GAV drifts open - all fixed

Thanks for pointing out the friction arrangement inside the carburator. I took the GAV housing out and closed down the four fingers. Also, I reformed the C-clip to provide more friction and all is well now.

Thank you Ford Barn.

Tom
 
This may sound a little goofy, when you find where the engine runs best make sure the little *** on the knob is in the down position. That why the nuts for the junction box are made the way they are, that little ball at the end tends to turn to the bottom when they get loose and that little counter weight helps keep them from turning off.
I have seen the instruction to remove the little round clip in at least two places, have yet to follow that idea.
 
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