MTFCA Forum

Yesterday, I went on a HCCA tour with my ‘14 touring that had more hills than I expected, and while I had plenty of fuel to cover the distance, there were a number of long, steep hills that caused some issues. The first long hill resulted in a couple of surges as the carb almost went dry, but then the road pitched to slightly less steep and the car ran well enough to the crest of the hill. The next adventure was after a “detour” (following local members that I thought were more familiar with the route) that took us down a 15% grade. When our detour was discovered, we had to retrace our route, which meant going back up that steep grade on a curvy 2 lane highway. With about 3 gallons left, the hill was too much and the car quit at the steepest part. I eventually backed the car down to a driveway turnout with brakes alone (and yes, the reproduction AC brakes do work in reverse). Once out of traffic, I turned the car around and went up in reverse. This was my first time doing that on a well travelled highway. The car ran well enough, although by the top of the hill, the radiator was hissing and spitting noticeably.

Turning back around, I re-loaded my passengers and motored off to our next stop. Of course, the final stretch of one lane drive to the property was even steeper than that previous section of highway, although not nearly as long. Knowing that the carb could run dry, I tried making it up on momentum, running as far as I could with the fuel in the bowl, but to no avail. At first cough, I turned the car around and proceeded up backwards. But this time, I was still in Ruxtell low, which made it easier but kept me on the steep stuff for longer. This time, the radiator was quite upset.

Making it into our destination, I parked, let things cool down, checked the water, which ended up only down about a pint. I was able to borrow a few gallons of fuel to get out of the hills. The car ran well and kept her cool for the rest of the day.

But after getting home and putting the T away, I was pondering why both steep hills in reverse resulted in boil-overs. My gut feel is that the thermo-siphon is degraded with a steep nose down attitude. It’s possible that on the steepest part, the head over cylinder 4 might have been the highest part of the cooling system, effectively stopping all cooling. But certainly, anywhere close to that would slow the flow considerably.

In any case, if you ever find yourself in a similar situation, keep this in mind and keep your climbing time in reverse as short as possible.

Keep crankin’,
Eric

Staying consistent with Forum Rules, I can state that there absolutely is a cause to your problem, and there is absolutely a solution.

A Model T with 3 gallons in the tank should pull any hill that low band can tackle.

Feel free to contact me for the solution.

Get Scott’s needle valve. They work! Thanks for making them Scott.

Could it be that when you go forward there is a natural flow of air through the radiator. In reverse, not so much.

Mike

Pulling up a long, steep slope in reverse will tend to cause the engine to run hotter than normal. Anything that tends to lower the radiator relative to the engine such as descending a steep slope or backing up a steep slope will increase the tendency to overheat. Making fuel system improvements will make your car more reliable in hilly country and prevent the need to back up steep hills.

Re: Airflow ... I believe you are correct.

I guess that I should have mentioned that my ‘14 is running a stock Holley G carb. I do have a high-flow SC float valve on my shelf, but haven’t got around to putting one of those new-fangled NH carbs on the car. Maybe there is a similar option for the earlier carbs.

My fuel might have been a little bit lower at the time. After the cool down at the top of the second hill, my gas measured 2 gallons on the stick.

Keep crankin’,
Eric

Steve,

Trust me, it was not my first choice. That was my biggest concern, getting squirrelly in reverse. Surprisingly, that was not an issue. But I was pretty focused and even in ruxtell high, the backing up speed was manageable.

I do have a set of running board cans, but all of the gas falls out of the bottom of the red one before I get a chance to even lock them in the rack.

Of course, had I known then what I know now, my tank would have been full before I started and the whole tour would have been much more uneventful.

Another case of live and learn (hopefully).
Eric

36mike wrote: ↑

Sun Jul 06, 2025 3:57 pm

Could it be that when you go forward there is a natural flow of air through the radiator. In reverse, not so much.

Mike

That was my first thought too, Mike. And I’m sure that having to rely on the fan alone for airflow didn’t make things better. But the effect of tilting the entire thermo-siphon system is not something that I have ever seen discussed here or in any T literature. And in my opinion, that had a bigger effect on heating up the engine so quickly.

Keep crankin’,
Eric

Oversized and cheap. I love auctions.

You backed a Model T down a 15% hill successfully ? Quick ! Go buy a lottery ticket ! You’re the luckiest man on the Forum. Ultra squirrely would be my description. I’ve witnessed 2 Model Ts being laid on their sides when caught up in a similar situation. Maybe the AC brakes saved your bacon. And if you had 2 gallons on board at the top of the 2nd hill, you didn’t start the day with much more. And I respectfully disagree with Scott. Three gallons in a pre 25 gas tank on a 15% hill is a guaranteed fuel starvation. We usually drive 60-120 miles a day and one should start every day on a full tank - especially in hilly terrain.

Thanks George,

I had 5 gallons on the stick before I started, which would have been fine for the planned 40 miles if on the flat lands that I am used to. But with the hills and the unplanned detour later in the day before the real adventure started, things just didn’t turn out as I had expected when I got out of bed in the morning.

I’ve got no complaints, nothing broken, nobody hurt. Just another adventure with old-timey cars. It’s a hobby, I choose to do this, and the stories afterwards are the best part.

Keep crankin’,
Eric

Eric; great attitude ! You’re the kind of hobbiest that makes Model T touring enjoyable. One reason I start each day with 10 gallons in the tank is the detours and I easily get lost. ….. ) yes; every day Model T driving is an adventure and the folks you meet make the tour.

Just one of these can be your friend.

Scott’s valve will make a BIG difference. I have seen it on 2 different cars. Can pull hills with almost no fuel in tank with one. Without no way. Dies from no fuel.

Change to any NH and no fuel worries.
Again big shout out to Scott for his valves and other work. Dan

Eric,
That was, indeed, one of the hilliest tours that I have ever been on! A full tank of gas and momentum can be your friend. And just when you think that you will beat a hill, the guy ahead of you misses a shift!

I'm so glad so many people made new friends.

I watched a bloke manage the low fuel problem on a steep driveway once. I was most impressed. As we only had two or three miles to the destination, he had not filled up ready for the trip home. Part way up the car stuttered and he immediately turned across the driveway. Now on the flat, the carby got a recharge, and he had another go at the hill. He repeated the routine three times before he got to the top. I wouldn't try this on an open road though!

Allan from down under.

Fuel pressure is always marginal with an under seat tank. It diminishes further as the fuel level drops. Anything that raises the carburetor relative to the fuel tank, such as a steep incline, reduces fuel pressure. Heat always seems to aggravate any weakness in fuel systems. Fuel demand is high when climbing a steep hill, at the same time that fuel pressure is lower than normal. Anything that enhances fuel flow will be of benefit in hill climbing situations and other situations where fuel demand is high.

Am I to assume if you'd started with a full tank this post wouldn't be here? That's what it reads like.

Here is my solution after fighting the hill climb problem for years. I used to carry an extra 5 gallon can to top off the tank. Now I don’t. My tank is always pressurized.

viewtopic.php?f=2&t=48188&p=364774&hili ... ng#p364774

ewdysar wrote: ↑

Sun Jul 06, 2025 4:29 pm

… Of course, had I known then what I know now, my tank would have been full before I started and the whole tour would have been much more uneventful.

Another case of live and learn (hopefully).
Eric

Hi Charlie,

You are correct. I posted that earlier. But the obvious answers are easier after the fact, almost all of mistakes in my life could have been avoided if I had only done something different to begin with. And I would have had many fewer adventures with stories to tell about them.

While this story is entertaining, the revelation for me was the observation that measurably tilting a T nose down reduces the thermo-siphon’s ability to cool the engine. Going forward down a steep hill? Not a problem, there is more cooling available than you need. And we’ve all heard that Model T’s can be backed up steep hills if fuel starvation rears its ugly head, regardless of how you got there, even non-T people seem to know that. Until now, I had never heard that doing so for more than a short spell will inherently cause a boil-over. Heck, even idling while parked, if the car is noticeably nose down, will probably cause the temperature to climb higher than you expect.

I’m filing this one as another Model T idiosyncrasy that won’t come up often, but if it does, there’s no need to go looking for other causes.

Keep crankin’,
Eric

I installed a 12 volt battery in my 1915 touring car. Since it has no starter and generator, and all the lights are LED (except for the magneto headlights)
I installed a 12 volt fuel pump, next to the under-the-seat fuel tank with hoses and a switch. I don't use the fuel pump to supply gas to the carb. I use it as a transfer pump. After spilling gas all over everything, when trying to use a 5 gallon can, I can now simply drop the inlet hose to the pump in the fuel can, and the outlet in the tank, and flip the switch on. No more spilled gas! When I've finished transferring the fuel, I join the two hose ends together with a brass serrated nipple to keep gas from spilling out onto the tank. there is plenty of room to loop the fuel line around the tank, and then close the wooden door, and put the seat back in.

The other thing I did, since the gas cap is brass on my car, was that I bought a piece of (K&S) flat brass stock from Ace hardware, and laid out and stamped it with lines and gallon numbers, identical to the wooden dip stick for a round tank. I bent the end at 90 degrees, and soldered it to the bottom of the gas cap. Now, instead of having a smelly wet wooden dipstick to put away, I just pull the cap off, and look at the fuel level on the permanent dip stick on the cap!

Regarding your cooling experience when going in reverse, remember a '14 hood has no louvers to help with air flow, and that may well be why you heated up a bit. If you have engine pans, they add to the issue. In reverse, your fan is actually reducing the air flow - Try popping the hood off and setting it in the back seat next time you need to climb a long hill in reverse.
Check the screen in your sediment bulb!

Dan McEachern wrote: ↑

Mon Jul 07, 2025 12:05 pm

Regarding your cooling experience when going in reverse, remember a '14 hood has no louvers to help with air flow, and that may well be why you heated up a bit. If you have engine pans, they add to the issue. In reverse, your fan is actually reducing the air flow - Try popping the hood off and setting it in the back seat next time you need to climb a long hill in reverse...

Hey Dan,

That makes sense. Certainly an easy thing to do in the moment, if anyone finds themselves in a similar situation. Thank you for a great tip!

But with any luck at all, I'll never have to do it again.

Keep crankin',
Eric

While I loved the Holley G that came with my '17 I learned it had some drawbacks. When compared to a NH, the NH actually produces more power. Add to that the Scott Conger Full-flow valve and most of the problems you described are eliminated. FWIW, we did a side by side dyno test of a Holley G and a NH on the same engine with the attached results. I've installed a NH and been very happy with it. Also, you might want to know that fuel consumption with the G and the NH with the full-flow valve is unchanged. I just don't get any sputtering when the tank gets low.