MTFCA Forum

After suspecting a fuel flow problem on the open road I decided to time the flow from the NH fuel bowl drain.
1914 with oval under seat tank with original outlet tap and metal fuel bowl.
Car has a plastic fuel filter halfway along the fuel pipe.
After each test the fuel was returned to tank.

So I could get comparable tests I used the following -

Using a one litre measure container with a line around 500ml (1/2 litre) mark.
Turn fuel tap off at carby inlet, drain the fuel bowl before I set the container
Turn carby inlet tap on and start stop watch when fuel starts running into container.

Took 1 min 48secs to get 500ml (Pressure via 3 1/2 gallons in the tank).
When I removed the inlet to carby pipe from the tank side of the carby located fuel tap and tested again, it only took 30 secs to get 500ml.
I.E a third of the time.

Maybe the inline fuel tap slowed the flow some but I suspect it was the needle and seat.

Is there different flow needle and seats available (besides the ones designed for the M500)?

I reconnected fuel line then removed the plastic fuel filter, this only reduced the time from 1.48 to 1.45sec.

I then lifted the fuel level from 3 1/2 gallons to 6 3/4 gallons, this reduced the time to from 1.45 to 1.30secs.

Do you think this flow is good enough for open road consumption?

I tested my 23 Depot hack afterwards, same type of NH but this car has a larger Dia copper fuel line and it took 63 secs to get 500ml.
I don't know if is the larger fuel line or a bigger flow needle and seat that cuts the time by a third?

Your thoughts?

Kevin, your results might have been different if you used undersized US gallons as the head for you fuel flow. I was surprised that removing the fuel filter made so little difference. I guess you must have a relatively new filter. You may find a real difference if you fit one of Scott Conger's needle and seat conversions.

Allan from down under.

Hi Kevin, I'm also surprised that removing the inline filter made so little difference. I don't remember the flow figures, but we decided once that it would be a good idea to fit inline filters to a couple of our T's, and created starvation issues. Cars that used to climb hills ok, suddenly starved half way. We found that the gravity feed just couldn't get enough flow with the inline filters in place.
Btw, I contacted Scott Conger a while ago to ask about buying some of his valves but he was apologetic about not being able to sell to New Zealand unfortunately.

Haydon

The white plastic fuel filter was a used one I had on another T for about 8 years and removed when i sold it.
My conclusion is the filter didn't make any difference, I have fitted several types of filters on all my T's as its much better than getting a spec of rubbish in the carby which caused my very first T to die on the very open road trip.

The tank levels were via a Model T dipping rod which has the read out for each type of T fuel tank. So yes probably US gallons but it was more the level increase I was highlighting.

We go for a 45 min drive several times a week which includes 15 min drive around town then the rest is open road which includes a steep climb that most of my T's just get up in top gear. If it was a normal starve problem i would think it would show up on the hill. The last 2 drives I got almost home and it would cough and almost die but if I pull up and let it idle for 3 or 4 mins I can drive off again for a few blocks then have to do it again. Classic sign of fuel bowl refilling. Both were very hot days.
I filled the tank and went for the same drive and it didn't cough but I dont want to only be able to drive a distance if the tank if full.

Maybe I will change out the needle and seat with one from my spare carbs and measure the flow AND I just thought as writing maybe do a measure with no needle and seat fitted at all.

I was hoping somebody else had completed a similar flow measurement.

Thanks for your feedback

Get one of Scott’s valves. Have put on a couple pre26 cars( tank under the seat). They now climb hills with low fuel levels that they would not before.
I am talking less that two gals in tank low.
Good product, well made! Henry would approve.

Ditch the stupid inline fuel filter. Not necessary. Yes, adding Scotts full-flow needle valve does help especially in a heavier car but yours is only a "light weight" '14! Maybe the screen in the "potato" is compromised? Maybe your fuel line is getting gunked up from winter layovers from fuel turning to varnish. All my fuel systems are clean, no need for filters, everything runs fine. No need to figure out fuel flow here!

500 ml is 16oz in less than 2 minutes. That’s a gallon in 16 minutes. My T gets 18mpg at 35+ mph at a little over 2 gallons per hour. So you should be getting plenty of fuel at your current flow rate.

A good screen and clean sediment bulb under the gas tank is all you need for a filter. Water or sediment go to the bottom of the bulb while gas is filtered through the screen. A good free flowing fuel line with both ends higher than the center so any vapors will rise either to the tank or the carburetor will prevent vapor lock. And a good free flowing needle valve at the carburetor and a clean carburetor help as well.
If you have the type fuel used in California it needs to be used within 3 months even if you drain the tank and use it in another vehicle. Otherwise the fuel will turn like shellac and plug things up.
Norm