1930 Model AA Cant Get Her Over 25 MPH

[Working Class Zero]

Test Drive report..........

Starts up good. Idles high. GAV 1/2 turn out.
If I turn it out or counter clockwise 1-1 1/2 it helps the idle come down a bit, but if I leave it there when driving it runs rough. turn it all the way clockwise and it runs pretty good but come to a stop and she's idling quit high.

Feels pretty good for the most part when ripping along, but I'm still just literally watching my gas gauge go down. i've only driven 22 miles since i filled her right up and I'm already approaching 1/2 a tank. holy moly.

[Droobie]

Kane I am in love with your truck!!!!! It is SWEET!!!!!

[Working Class Zero]

Originally Posted by Droobie

Kane I am in love with your truck!!!!! It is SWEET!!!!!

Thanks. I am in love with it too.......
Once she's tuned in I will love her even more.......

[ctlikon0712]

Maybe your throttle shaft on the carb is pulling in air at idle. When you back the Idle speed screw out all the way does she want to die? If not its pulling air in around the shaft where its worn in the carb housing or the throttle shaft and butterfly valve arent lined up correctly in the bore. If she does want to die then you adjusted the Idle mixture somewhere around 1.5 turns out and reset the Idle speed right? They temd tp react to each other so you might have to go back and forth a few times with them.

[theHIGHLANDER]

Kane, I'm going to avoid the xmas rush and start hating you now. That truck is seriously F'n sweet!

Ok, I'm going to throw some observations at ya. You turned the column to correct your timing range. You may have moved the warm up throttle outta range a bit. High idle. Mileage concerns, if you're turning the GAV that much and it runs ok until idle, well then at idle it's running too fat. Trust it. If it idles good and runs good warmed up at 1/2 to 3/4 out on the GAV, leave it alone until you drive it cold weather. The idle mixture screw, with everything else good and your timing at 1/2 or so, adjust the idle no more than 1/8 turn at a time and let the motor "catch up" to that adjustment. You'll find the sweetest spot when you hear a difference in the "hiss" of mixture in the carb. It'll be silent when it's way in, sound "wet" or a bit bubbly when it's way out, but right before that sound gets completely audible, that's usually the sweet spot. Needle and seat needs to function properly. Under load, a big truck like that will drink almost all the fuel you give it. It's heavy, it's not the same as the cars, it's gonna be a bit thirstier, but I'm with you about too much gas being used. I drove my pickup about 20 miles give or take and didn't even notice the movement of the fuel level. Around 3/4 when I drove it, around 3/4 when I drained it, now reads empty. Control your fuel flow and you are home free. Again, as big and heavy as it is, it'll probably use extra fuel that cars would be smokin and belching over.

Did I say your truck was bitchin? It is. Hang in there bro, you'll get it.

[Bob C]

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Dual wheel trucks had 6.00 x 20 front and rear, trucks with single wheels had 6.00 x 20 on
the front and 32 x 6 (6.50 x 20) on the rear according to the Service Bulletins.

Bob

[Working Class Zero]

Originally Posted by ctlikon0712

Maybe your throttle shaft on the carb is pulling in air at idle. When you back the Idle speed screw out all the way does she want to die? If not its pulling air in around the shaft where its worn in the carb housing or the throttle shaft and butterfly valve arent lined up correctly in the bore. If she does want to die then you adjusted the Idle mixture somewhere around 1.5 turns out and reset the Idle speed right? They temd tp react to each other so you might have to go back and forth a few times with them.

Craig, I fired it up and backed off the Idle speed screw and it just kept running exactly the same. No fluctuation in the idle whatsoever. I even took the screw right out and she was still running strong, with no difference.

[Working Class Zero]

Originally Posted by KANE MCAFFER

Craig, I fired it up and backed off the Idle speed screw and it just kept running exactly the same. No fluctuation in the idle whatsoever. I even took the screw right out and she was still running strong, with no difference.

So what would be my next step if this is happening.......

[ctlikon0712]

Got to find where the air is comming from around the butterfly. Take the throttle and pull the top back. Should try to close it further. Does engine slow? If not put your hand over the carbs opening. Does it then want to die, or do you hear the his of air from somewhere? Maybe where the shaft goes throught the housing? If not the butterfly plate might have been installed in the shaft wrong and not be sealing up against the bore all the way. Also, check where the carb bolts to the intake. Could the ears be bent where it mates up, or a bad gasket? Sucking air there? Let us know.

[Tom H.]

Kane, very nice truck. With 6:00 - 20 rear tires our 32 AAB will run about 45mph, but feels comfortable in the 35 - 40 range. I don't know the mpg but it seems like every time I run her around for a few miles it takes another gallon. Best of luck with the big iron.
Tom H

[Modelakid31]

I would run the spark all the way advanced(down) when driving normal flat'ish roads and then when going up an incline or hill bring the spark up to adjust the power needed.

Especially if the engine is timed right run with the spark all the way down. shouldnt be a problem.

[Modelakid31]

also, Beautiful truck! she's a keeper!

[Working Class Zero]

Originally Posted by ctlikon0712

Maybe your throttle shaft on the carb is pulling in air at idle. When you back the Idle speed screw out all the way does she want to die? If not its pulling air in around the shaft where its worn in the carb housing or the throttle shaft and butterfly valve arent lined up correctly in the bore. If she does want to die then you adjusted the Idle mixture somewhere around 1.5 turns out and reset the Idle speed right? They temd tp react to each other so you might have to go back and forth a few times with them.

Sorry I think i got mixed up with all the "screw names". When you say: "When you back the idle speed screw out all the way does she die" you mean the screw on the throttle lever as opposed to the idle mixture screw on top of the carb right? I had thought we were talking about the one on top. If I back off the screw on the throttle lever she does die and I get get a nice sounding idle if I adjust there.

Again when I said I backed it out all the way and there was no fluctuation in idle I was referring to the idle mixture screw on top.

Adjusted at throttle lever to nice idle does however now stop it from going full throttle with the pedal to the wood.........

[Working Class Zero]

I also have a family of birds nesting in the rafters of my shop. They are very loud, however not causing any of my AA problems........ lol

[1931 flamingo]

Kane: With engine running take a spray can of wd-40 and spray around the gasket areas of the intake/exhaust manifolds, if there is a leak the idle will smooth out. Does your intake manifold have a vacuum fitting (for w/shield wipers)?? Ck that line for leaks, also the vac hose that runs from top of header over to the wiper motor.
paul in CT Isn't this fun?

[Working Class Zero]

Originally Posted by 1931 flamingo

Kane: With engine running take a spray can of wd-40 and spray around the gasket areas of the intake/exhaust manifolds, if there is a leak the idle will smooth out. Does your intake manifold have a vacuum fitting (for w/shield wipers)?? Ck that line for leaks, also the vac hose that runs from top of header over to the wiper motor.
paul in CT Isn't this fun?

Wd40, that was it...... Gonna try that. No wiper vacuum, intake is an original, but must have been off a roadster or something with a hand operated wiper.

[ctlikon0712]

Yes, the Idle speed and Idle mixture are two different things but if you change the idle speed(screw on the lever), it moves the butterfly and changes the Idle mixtures(screw on top) setting so you have to readjust it somewhat. Yea so the mixture you want in all the way and back out 1.5 turns and then play with it at a low idle speed to get the best idle. Should be between 1 to 2 turns off the seat position.

[Tudortomnz]

Originally Posted by mass A man

You really need a reprint of the original owner's manual. It is not expensive and will set you straight on the Model A basics, (settings, driving, adjustments...) Your carb may need a clean/adjust, now that you may have a good manifold seal to block. Plugs should not be sooted up if you are driving with proper adjustments. Other more in-depth repair books are out there, many are a great value to the A owner. Lastly, we're always here too!---Pete.

I think this is very good advice to someone new to stock Model A's. A reprint handbook will tell you how to start, drive & look after the vehicle.

[dmaxweb]

Originally Posted by KANE MCAFFER

Sorry I think i got mixed up with all the "screw names". When you say: "When you back the idle speed screw out all the way does she die" you mean the screw on the throttle lever as opposed to the idle mixture screw on top of the carb right? I had thought we were talking about the one on top. If I back off the screw on the throttle lever she does die and I get get a nice sounding idle if I adjust there.

Again when I said I backed it out all the way and there was no fluctuation in idle I was referring to the idle mixture screw on top.

Adjusted at throttle lever to nice idle does however now stop it from going full throttle with the pedal to the wood.........

All about zenith carbs
http://www.model-a.org/default.html

[Working Class Zero]

Originally Posted by dmaxweb

All about zenith carbs
http://www.model-a.org/default.html

Good link thanks.......