Acts fuel starved after 10 minutes

[heneste]

If the float is not set properly and your jets are allowing too much flow, you may be depleting the fuel in your carburator bowl.

My friend's '29 started to act this way after he adjusted the carb a bit.
He also had an issue with tank blockage as he would get some gas draining through but nowhere near the adequate flow to the carburetor.
It could be that you have sediment right around the outlet valve of the tank that blocks your fuel flow intermittently as your car vibrates.
I would try blowing back the line to the tank while opening the gas valve and then shut the gas valve off and try the car again.

[FL&WVMIKE]

Mitch//Pa mentioned loosening the gas cap. Did you take it off ?
You might actually have a RADIATOR cap which is made to be air/water tight. The GAS cap has to be vented, or you will creat a vacuum in your gas tank, which will lead to fuel starvation.
Do you hear a WHOOSH when you take off your gas cap ? That is the vacuum, being released,
Good luck !
MIKE (mikeburch)

[nkcarizona]

Took another crack at it today. Pulled plug on carb to check flow through the carb. Seemed a little weak. Pulled line into carb back to ferrule and the same at the gas bulb. Seemed to improve flow a little.

Took a drive. Better but not perfect. No problem cruising at 30-35 but when I pushed to 40 it started to starve. Is it possible the needle valve seat orifice is too small? I will pull the carb to check for blockage.

[29 Tudor]

I had a bad needle an seat in mine. I calculated that the worst case flow I needed was enough to support 5 MPG. I know it doesn't burn that much fuel but I wanted a safe margin so that's what I used.

At 40 MPH, it takes 90 seconds to go one mile. At 5 MPG, you need 1 quart in 112.5 seconds. I used a quart jar below the carb with the plug out and measured how long it took to fill it. After I replaced the needle and seat and got much more flow than that, the problem was gone.

I would MEASURE the flow and then start from there to determine where the issue is. For example, if you do not get the flow with the plug out of the bottom of the carb, pull the line off and see if the open line will fill the jar in the required time. If that works, pull the needle and seat out of the carb an do the test with it out. That will tell you where your problem is.

Steve

[nkcarizona]

Good suggestions on checking the flow. I know that the flow I get at the carb inlet is many times that out the bottom of the carb. I was using a pint cup to catch the flow and in several seconds it did not begin to fill up. I will quantify the flow, and I suspect pull the carb to see what the problem is.

[pooch]

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Originally Posted by 29 Tudor

I had a bad needle an seat in mine. I calculated that the worst case flow I needed was enough to support 5 MPG. I know it doesn't burn that much fuel but I wanted a safe margin so that's what I used.

At 40 MPH, it takes 90 seconds to go one mile. At 5 MPG, you need 1 quart in 90/5 or 18 seconds. I used a quart jar below the carb with the plug out and measured how long it took to fill it. After I replaced the needle and seat and got much more flow than that, the problem was gone.

I would MEASURE the flow and then start from there to determine where the issue is. For example, if you do not get the flow with the plug out of the bottom of the carb, pull the line off and see if the open line will fill the jar in the required time. If that works, pull the needle and seat out of the carb an do the test with it out. That will tell you where your problem is.

Steve

40 MPH at 5 MPG is 8 gallons per hour.

64 pints in 60 minutes, a fair bit less than your quart in 18 seconds.

[nkcarizona]

pooch, you are right it is 64 pints per hour or about a pint a minute. I am not getting anywhere near that through the plug under the main jet, more like 3 oz per minute. . Given the size of the jet I don't think that gravity flow would put that much flow through the main jet, or am I wrong.

Has any one measured the flow they get through a Tilly at the bottom plug?

[Purdy Swoft]

Check float setting. Float setting on the Tillotson is one inch. with the two halves of the carb seperated , I usually just turn the upper half of the tillie carb upside down in my hand and set the float level. as has been said it is always best to install a mesh stand up filter in the cut off valve so as to filter any trash in the bottom of the tank from restricting flow through the cut off valve and fuel lines. also the Tillotson model X or XF carbs don't have a pre filter over the needle valve assembly like the Zenith and some other carbs do. Magnets placed on the bottom of the tank near the cut off valve will attract rust and prevent it from causing blockage to some extent.

[29 Tudor]

Pooch,

Obviously you're correct. Try a quart in 112.5 seconds. My pencil must not have had enough fluid in it.......

I'll correct the original post so someone else doesn't use the incorrect math.

Thanks,
Steve

[Tom Endy]

Try this suggestion:

Remove the fuel line from the car and blow shop air through it. Blow shop air into the tank fitting on the firewall. You can also run a coat hanger wire into the tank fitting. Check that there is not too much fuel line protruding past the ferule at each end. Grind it down if it is. Reconnect the fuel line at the fitting on the fire wall. Turn the gas valve on and see if you are getting a good solid steady stream of fuel. Check that the gas cap is properly venting the tank. I suspect you have a partial fuel blockage somewhere either in the tank or the line.

Tom Endy

[pooch]

Just got back from a swap meet.

The gravity flow figures were handy to bandy about.

5 MPG is good to go for, as it seems consensus shows an A does about 18 - 20 MPG if in good nick .

One would have to allow for at least 10 MPG, say if going up Pike's peak at a minimum as 18 - 20 MPG is an average up /down/level/go/stop.

So I guess 1/2 a pint per minute would be the minimum flow one would hope for .

Of course, Aus /NZ/ Britain have to adjust MPG as our gallon is bigger than yours.

[nkcarizona]

Just to folllow up.It was not a carb problem. I swapped carbs with my '29 Fordor and the Fordor ran fine with the Roadster carb. I seemed to have initially a fuel flow problem with the Fordor carb, hardly started, but I pulled the carb, found a little sediment in the bowl, cleaned jets, etc. and found it would run, although after 10 minnitues on the road there was a little hesitation. Even though the timing light showed spark when acting starved, I changed out the coil for a new Axcel coil. Runs fine now, no starving action, but it spits coolant after I stop when back home. I had this problem initially with the rebuilt engine, but not recently. Have about 500 miles on the engine. Would a hotter spark cause the engine to overheat?

[gnolnor]

It is a matter of physics. Gas cannot flow in a vacuum. Make sure the hole in top
of the gas cap is open to out side air. Original '28 and '29 screw on gas caps have a
hole in the top.

[tbirdtbird]

Would a hotter spark cause the engine to overheat?

No

[Purdy Swoft]

I agree with tbirdtbird . But retarded timing or improper use of the spark lever would.

[Mike V. Florida]

Originally Posted by nkcarizona

Just to folllow up.It was not a carb problem. I swapped carbs with my '29 Fordor and the Fordor ran fine with the Roadster carb. I seemed to have initially a fuel flow problem with the Fordor carb, hardly started, but I pulled the carb, found a little sediment in the bowl, cleaned jets, etc. and found it would run, although after 10 minnitues on the road there was a little hesitation. Even though the timing light showed spark when acting starved, I changed out the coil for a new Axcel coil. Runs fine now, no starving action, but it spits coolant after I stop when back home. I had this problem initially with the rebuilt engine, but not recently. Have about 500 miles on the engine. Would a hotter spark cause the engine to overheat?

90% of all fuel problems are electrical.

[Tom Wesenberg]

Originally Posted by gnolnor

It is a matter of physics. Gas cannot flow in a vacuum. Make sure the hole in top
of the gas cap is open to out side air. Original '28 and '29 screw on gas caps have a
hole in the top.

I've seen repro caps with the hole in the top, but original caps should have 6 small slots around the lower cap edge.

[Rex_A_Lott]

Changing the coil by itself wont make it run hot, but by fixing your other problem, now you are able to drive more than 10 minutes at a time. The overheating was probably there before, you just never drove long enough for it to show up.
Lots of info here by searching overheating....or start a new thread.
Are you having fun yet?
Good luck!

[pooch]

Originally Posted by nkcarizona

Just to folllow up.It was not a carb problem. I swapped carbs with my '29 Fordor and the Fordor ran fine with the Roadster carb. I seemed to have initially a fuel flow problem with the Fordor carb, hardly started, but I pulled the carb, found a little sediment in the bowl, cleaned jets, etc. and found it would run, although after 10 minnitues on the road there was a little hesitation. Even though the timing light showed spark when acting starved, I changed out the coil for a new Axcel coil. Runs fine now, no starving action, but it spits coolant after I stop when back home. I had this problem initially with the rebuilt engine, but not recently. Have about 500 miles on the engine. Would a hotter spark cause the engine to overheat?

After it spits water and cools down, how far down is the level of water ?

You may just have it over full .