GAV setting and trouble shooting?

RTC1930

RTC1930

Senior Member
Hope I'm not over my question limit but just curious what others experience has been.

I mentioned this issue in my last post regarding the steering and finally got my plugs pulled today, see pic below. The issue is after the car is warmed up im unable to close the GAV at all and need to leave it open 3/4 to a full turn or the carb begins popping and stuttering at high rpm while accelerating. It seems like the car is running rich but it does not want to run right any leaner. Is it possible this is just a float adjustment issue, it nearly stalls when facing downhill in our steep driveway. Im going to check with float gage tomorrow. Where else should I look? Motor is fresh rebuild, only 3 miles on it so far, coil points condenser are new, timing seems good, idles smooth, intake was machined flat. I read the other posts on the GAV and it sounds like it needs to be open slightly for the new fuels but mine seems excessive.

It runs pretty good with GAV open though its a little flat at the top end. I have new 3x plugs to replace the autolights but am hesitant to switch cause I don't want to foul them up.

Thanks,
Bob NJ

1038367267_dXwdD-M.jpg
 
the plug looks a bit on the lean side. Your description sounds lean too. Look for vacuum leaks, low float setting, clogged jets or passages in the carburetor. It should run well with the GAV at 1/4 open to closed.
 
That plug looks good to me.

This might help;

Reading spark plugs can be a valuable tuning aid. By examining the spark plug insulator color, an experienced engine tuner can determine valuable information about the engine's overall operating condition.

Normal: Grey to Light Golden-Brown Color
  • This condition is ideal, the spark plug and engine air/fuel mixture are operating properly.
Dry: Black Soot Buildup
  • Air/fuel mixture is too rich, the carburetor settings are incorrect, or the Air filter (if it has one) is dirty or has mounting problems.
  • Spark plug heat range is too cold for the operating conditions.
  • Ignition system problems causing a weak or intermittent spark.
Wet Fouling: Shiny, Wet, Black Appearance
  • Excessive use of the choke (gas fouled)
  • Prolonged low rpm operation (gas or oil fouled)
Excess Deposits: Bumpy, Chalky Buildup
  • Poor fuel quality
  • Oil leakage into combustion chamber

Overheated: White, Blistered, Melted Electrode
  • Lean air/fuel mixture
  • Spark plug heat range is too hot for operating condition of the engine
  • Plug is not properly gapped and/or torqued onto head
  • Overly advanced timing
A detonation problem would show signs, such as silver specs, black specs, or melting or breakage at the firing tip.
 
I'm with Mike! That plug looks great! If you can turn the GAV in -- clockwise -- and the engine starts to stumble, you are lucky. Your GAV works! Turn it back out a 1/4 twist and you're golden! At your 10,000 mile check up (my Dad, who drove Model A's before they started getting "restored," always told me that we mess with them too much. Just check the oil, gas, and coolant and drive), if the plugs still look like the picture, take 'em to your next club meeting. You'll have bragging rights!
 
Thanks for the replies! Guess I need to learn a thing or 2 about reading the plugs. I kinda thought the center indicated lean but the outer ring seamed sooty so I wasn't sure what to make of it. I did snug up the manifold a bit to 35lbs but I doubt that was it.

Bruce, my Dad keeps telling me that same thing! Every time I explain the function of something to him he says "really, thats what that does, I never touched it". Like the 3rd brush adjustment (and the brakes). Amazing the difference the internet makes.

I think I just need to get it out more and start learing from experience. I have so much more time and money put in then I ever anticipated for a driver that I need to get over my nerves of screwing something up. I admit I got a little carried away in my resto, its a sickness! Taking it to its first car show tonight!!!

Bob, NJ
 
Did you say the engine has "3" miles on it? Come back to us when it has 500 miles on it. You can't draw any conclusions on an engine that isn't broken in yet. Your Dad's right - keep you hands to yourself! Quit messing with things and get out there and drive it and enjoy. Sorry if I sound harsh, but these cars are so sweet they don't deserve to be worried to death. They just want to have fun!
 
Larry Seemann said:
Did you say the engine has "3" miles on it? Come back to us when it has 500 miles on it.
Click to expand...

Yeah, I was surprised no one called me out on that sooner. Took it out again tonight and ran really strong so I'll just start racking on the miles and quit fussing. Thanks for the help anyway, its just reassuring.

Bob, NJ
 
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