Fuel Filter Restriction

[ian Simpson]

Originally Posted by H. L. Chauvin

Strong Model A Steel lines for "constant" gravity fed fuel to the engine compartment were designed & installed for ultimate highway safety.

The in-tank cylindrical vertical screen & the paper NAPA 3039 fuel filter in the glass sediment bowl can eliminate tank crud, moisture in fuel, & rust problems on any lengthy tour.

If one wants Show Time? .... just remove the NAPA 3039 fuel filter from the glass bowl.

I concur, although as we are not concerned with the show scene I cannot comment on removing the NAPA 3039.

[ian Simpson]

Originally Posted by Mitch//pa

Dick shouldnt it be a nice flow that shoots a ft from the line and not a good dribble

It used to when I was younger, now I do what I can do.

[Dick Steinkamp]

Originally Posted by ian Simpson

It used to when I was younger, now I do what I can do.

Ain't it the truth.

[1930-fordor]

#10 post by 29er is the exact thing I did, with the magnet trick. Never a problem with fuel again.

[Chuck Sea/Tac]

Originally Posted by Dick Steinkamp

Here's what you (or I) could do in order to define "an acceptable good dribble"

You can use your own numbers, but here's a suggestion...

Let's say you get 15 MPG at 30 MPH in a Model A. It is, therefore, burning 2 gallons in an hour, or a gallon every half hour, or a quart every 7.5 minutes, or a pint every 3.75 minutes or a cup every 1.875 minutes.

As long as you are getting a cup every 2 minutes or so out of the open fuel line the car will run as well as if you are getting a quart or more in the 2 minutes. The carb can only take what the engine is consuming.

Getting a cup of fuel out of the open fuel line in 2 minutes will look pretty much like a good dribble (at least to me).

Of course you will have to adjust the above numbers if you get worse or better mileage.

Again, I agree with you that you should get a nice steady stream of fuel out of the open fuel line and if you don't you should look for the partial blockage. But the lack of a good steady stream should not cause the problem that the OP posted as long as the carb is getting enough fuel for the float bowl to remain full...and if it isn't getting enough there will be a more severe problem than needing a richer mixture (ie: the engine will stop running).

Yeh, but Dick, the variable is, how do you control a dribble caused by a partial restriction?? Sometimes it's a big dribble, then it a no dribble.
I had a cheap napa in line filter, which would work until you tried to pull a hill under full throttle. I got rid of it, installed a dirty leg, and flushed my tank.

[H. L. Chauvin]

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Partial Fuel Restriction Concerns ..... Hmmmmm ?????

Appears the problem with a good dribble is it works until one mashes on the accelerator to pass a line of four (4) or so slow moving cars and one's Model A stalls because the driver finds his get up & go ...... has got up & went.

Seems similar to a guy with partial artery blockage "sitting" in his rocker on his front porch; then the young good looking mail lady toots her horn for him to sign for a package 35 yards away, way out front, by the mail box.

This 86 year old guy, (same age as his Model A), looks at her big boobs, takes off running wide open, and runs out of breath on his 15 yard line.

Unless Model A parts suppliers start offering something similar to Model A Viagra Fuel Tank pills, seems wise to try to get as close to Full Fuel Flow prior to departure on a long Model A tour.

Hope this blood flow comparison helps Model A owners to remember some of the disadvantages of Model A dribbles.

[Dan Partain]

You might check this if you have your fuel filter off -

https://www.youtube.com/watch?v=M9ECeK_xf1c

[Dick Steinkamp]

Originally Posted by Chuck Sea/Tac

Yeh, but Dick, the variable is, how do you control a dribble caused by a partial restriction??

Originally Posted by H. L. Chauvin

Appears the problem with a good dribble is it works until one mashes on the accelerator to pass a line of four (4) or so slow moving car

Guys, I am not a proponent of driving a car with less than full fuel flow. I also agree that if it is less, the cause should be discovered and fixed. I've said as much in posts 13 and 16.

What the OP stated was that he installed an in line fuel filter and now has to richen his mixture at the GAV in order for the car to run the same as it did before the filter. He felt reduced fuel flow to the carb could be the reason.

My point is that these two things (possible reduced fuel flow and the need for a richer mixture) are not related.

If the fuel flow is LESS than that required by the engine, the carb float bowl will eventually empty and the engine will quit running. No amount of making the mixture richer will stop this from happening. This is true for a partial blockage that is less than the overall requirement of the engine. It is also true for an intermittent blockage, or a blockage that is "on the bubble" and that a greater fuel requirement of the engine (ie...big pull up hill) will exceed the amount of fuel delivered.

If there is a reduction in fuel delivery but it is still sufficient to keep the float bowl filled under all conditions, there would be no change needed in the GAV. To the carb, the fuel level in the bowl looks exactly the same as with full fuel flow.

If there is a reduction in fuel delivery that is NOT sufficient to keep the float bowl filled under all conditions, the fuel bowl will empty and the car will quit running. No amount of fooling with the GAV will prevent this.