1930 surging at high speeds

S

STEPHEN FIELDS

Member
Howdy, I just bought a beautifully restored 1930 Coupe about a week ago. It kind of surged alittle bit at the top of 3rd, but I dismissed it initially. Ive tried re-setting the points (they WERE too close, under.05...I set them to .20) and now it runs worse....(although I may have set the points when the lever was at full advance; Ill have to re-check that) Ive inspected and cleaned all ignition components including the spark plugs. It will always run bad if you fully advance it, even if its idling or at speed. It Idles fine, and will run at 400 rpm or less to the point where you can count the revolutions, it will run all day like that. It Just has a problem at speed when its fully advanced; or any where close to full advance.
 
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STEPHEN FIELDS said:
Howdy, I just bought a beautifully restored 1930 Coupe about a week ago. It kind of surged alittle bit at the top of 3rd, but I dismissed it initially. Ive tried re-setting the points (they WERE too close, under.05...I set them to .20) and now it runs worse....(although I may have set the points when the lever was at full advance; Ill have to re-check that) Ive inspected and cleaned all ignition components including the spark plugs. It will always run bad if you fully advance it, even if its idling or at speed. It Idles fine, and will run at 400 rpm or less to the point where you can count the revolutions, it will run all day like that. It Just has a problem at speed when its fully advanced; or any where close to full advance.
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I think you mean .020
 
Set the points to .020, check the timimg. If it runs worse when you move your advance lever the lower plate wire may be on its way out. Do you have any play in the dist shaft? But if it surges you might have a fuel problem like its starving for fuel. Give the GAV a half or whole turn and see if that makes a difference. Even try choking it alittle while at speed when it surges. There will be more help and comments on the way good luck.
 
To elaborate on Mr. Miller's above comment .............. are you measuring point gap at 0.020", (twenty thousandths of an inch), with a feeler gauge ....... or are you measuring with a ruler or other device which divides an inch into ten (10) increments where you are measuring your point gap at two tenths of an inch.

Because of inexperienced mechanical assumptions, appears vintage car/vehicle Forums are always full of unexpected surprises.
 
As said, set points at .020" and check/set timing with lever fully up to TDC. When timing is correct the should idle slow and smoothly fully retarded, engine should increase at about half advance and run smoothly, at full advance the engine should run a bit rougher and start to roll. These monsters really don't need to be run at full advance [40º].

Your problem appears fuel related. Open the GAV and fuel cap to see if that helps.

Let us know and we'll go from there.
 
Mine did that, and the problem was the screen filter on the inlet of the gas shut off valve. I cleaned it and it ran fine.
 
I appreciate the help so far guys. I will try all above things....also another thing I noticed is my GAV will only turn about a quarter inch left or right.
 
Start with the GAV and figure out why it won't turn. Re-ck timing. Ck fuel flow. Ck for a vacuum leak. FWIW

Paul in CT

WELCOME
 
Ok; timing and ignition is ruled out. I checked it from one end to the other; new points and condenser ....but it still surged. So I did what someone suggested and pulled the choke out alittle ; and MAN she came alive! So it's fuel delivery. How much should the GAV be able to turn?
 
Re: 1930 surging at high speeds-Starting and use of CHOKE and GAV

GAV usage:

GAV will turn ABOUT 6 or 7 turns then you can remove the needle.

1. GAV 3/4 to 1 turn for startup when COLD, leave it rich while warming up. Reduce to 1/4 turn as engine warms up.

Pull choke for about a Second, any more will flood engine. If no start give it another one second shot

1a. If the engine starts and promptly dies that is your clue to turn the GAV a little more in CCW direction to make the mixture a little richer.

If too rich you will hear it "Bubbler" while running.

2. GAV 1/4 turn while running on flat after warm up.

Ford made the mixture a little lean so when you go to higher altitudes you can lean it out a little.

3. When climbing a long steep hill an additional 1/8th or 1/4 turn will give some extra power while climbing.

Note on a HOT or COLD start it helps to open the throttle slightly before choking.

I do not know why but some rebuilt carbs will start when HOT with no choke and no extra throttle. Others require a short shot of choke when hot.
 
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GAV usage.
It depends on which carburetor you're using.
Closed to 1/2 turn for Zenith
1/2 to 3/4 for Tillotson.

If the GAV adjustment doesn't fix it, then check for good 'lively' fuel flow. If that is good then it may be time to get your hands dirty and take the carburetor apart. Also, the fuel line shouldn't extend into the carburetor inlet too far.
 
Hi Stephen,

Looks like you found that your engine not operating properly at cruising speeds is a result of "fuel starvation".

Maybe your fuel tank is immaculate; however, it is not difficult to gas up at a filling station today and obtain somewhat dirty fuel, and/or, like that of most of us, we all have gas tanks that are over 80 years old and may have even slight rust and/or silt therein which may cause possible future fuel starvation.

To maintain a clean carburetor and to prevent possible repeat fuel starvation, (from today until infinity), it is never a bad idea to install:

1. An upright cylindrical "Fuel Tank Filter Screen", (Bratton's Catalog No. 13280; under $4.00) in your fuel tank above your fuel shut-off valve; and,

2. An in sediment bowl paper filter, (NAPA Gold Filter #3039), plus carry a couple of spares of this item.

A Model A stalling on today's fast moving modern highways with drivers texting and talking to their girlfriends on a cell phone is almost as dangerous as taking four (4) sleeping pills and going to sleep on a railroad track ....... or going to Syria or Western Europe wearing an American Flag Tee-Shirt.
 
Thanks all; I got it running good today ....I found out the fuel shut off had a small amount of debris in it....once I cleaned it; it ran perfect!
 
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