Engine stumbles on acceleration

aermotor said:
Get it started and running at the lowest idle speed and spray carb. cleaner around the manifold to block areas and if you get an increase in RPM chances are a intake gasket leak. Quick acceleration, not only from idle, has to start with a rich mixture and intake leaks will cause a lean mixture.

John
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I have found when using carb cleaner to check, if there are vacuum leaks, the motor wants to cut out not increase in RPM.
 
That's an interesting thought! The good thing about carb cleaner is that it evaporates. Doesn't make a mess as WD 40 would! I tried the propane torch method but I got no difference. (Torch not lit!)
 
Bill OH,
I tried regapping the plugs. I thought.025 was a bit tight so I went down to .030”.
I went for a long ride to check it out. To me, it ran OK but I think it ran better at .035”
I filled up the gas tank and added some Marvel Mystery Oil.
Somebody asked the type of plugs I’m using. They are Autolite.
 
Neshkoro said:
Bill OH,
I tried regapping the plugs. I thought.025 was a bit tight so I went down to .030”.
I went for a long ride to check it out. To me, it ran OK but I think it ran better at .035”
I filled up the gas tank and added some Marvel Mystery Oil.
Somebody asked the type of plugs I’m using. They are Autolite.
Click to expand...

.035" is the Ford recommended gap.

Saying that the plugs are Autolite is like saying the car is a Ford or whatever.
What number are the plugs?
 
Autolite ASP 3076 Sorry. I forgot to add the part number.
They are from NAPA and the only number they offer.
 
Question for diagnostic purposes. Does it stumble more, less or the same once it is warmed up?
I am thinking; if it hesitates less when warm, that would point to a lean condition. If it makes no difference, that may point to timing?
 
Neshkoro said:
Autolite ASP 3076 Sorry. I forgot to add the part number.
They are from NAPA and the only number they offer.
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You can order Champion 3X from NAPA and our store had them in for me to pick up the next day. 3X cost a lot more than the Autolite.
 
$3.29 vs $7.69 Autolite vs Champion. $32.00 and you're out the door with a set of Champion plugs. Not a big cost difference. Is there a big performance difference? If there is, I'll buy the Champion.
 
I was looking around at my past posts. I ran across this one about engine stumbling. I got to the part about spark plugs. I started looking on line for plugs. You can get a plug for $5.00 up to $32.00 each. What could make any plug worth $32 when you can get one for $5.00? I know about heat range and that stuff but almost 7 times cost? I suppose if the $32 plug makes your A run better then its worth it but its crazy. I'm not a cheap skate, but still.......tell me why they're better.
 
Neshkoro said:
I was looking around at my past posts. I ran across this one about engine stumbling. I got to the part about spark plugs. I started looking on line for plugs. You can get a plug for $5.00 up to $32.00 each. What could make any plug worth $32 when you can get one for $5.00? I know about heat range and that stuff but almost 7 times cost? I suppose if the $32 plug makes your A run better then its worth it but its crazy. I'm not a cheap skate, but still.......tell me why they're better.
Click to expand...

Aren't they supposedly the OEM plug? Important to the fine point community I would think.
 
I've always wondered the same thing. I use the Motorcraft TT10) plugs. In fact, I recently changed them for the first time after 45,000 HARD miles. In these engines, plugs should last a lifetime. I think any plug maker that recommends changing at say, 5 or 10 thousand miles is just trying to increase sales and is saying their product is no good.
BTW, the new plugs made no discernible difference.
 
Get rid of the fuel filter. Your carburetor might be warped causing a vacuum
leak at the cover gasket. The carburetor casting where the throttle shaft goes through might be warn causing a vacuum leak. Is your windshield wiper vacuum line sealed? The fuel level in the carburetor might be too low. I would try using a Zenith carburetor to see if your hesitation problem changes.
 
Get rid of the fuel filter. Your carburetor might be warped causing a vacuum
leak at the cover gasket. The carburetor casting where the throttle shaft goes through might be warn causing a vacuum leak. Is your windshield wiper vacuum line sealed? The fuel level in the carburetor might be too low. I would try using a Zenith carburetor to see if your hesitation problem changes.
 
Good Morning...I've run Champion W 16 Y plugs for close to 20 years and had good luck with them. They are gaped at 35 thousands and my points are set at 20 thousands. Many A's will tend to want to stall with a quick or panic stop. I have learned over the years to just pull the hand throttle down a little under those sorts of stops. The hand throttle is really a useful tool, if one pays a bit of attention to it...Ernie in Arizona
 
I realize this thread is a bit old but was having the same problem as described and after replacing so many stinking parts I found the problem to be with the fuel flow. Someone had previously used a gasket maker type stuff to try and seal the gas gauge. Little pieces of that had been falling off an partially blocking my fuel flow. I drained the tank. Removed both the valve and fuel lines. Blew everything out with compressed air. Vacuumed what I could out of the tank after letting it sit for a while of course. Put everything back together and it ran great. Then months later started getting a stumble at idle. Got rid of the Tiltson carb and replaced with a Marvel and now it’s purring like a kitten.
 
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