The only part of my car I've never touched is the carburetor. It's a Kingston L4 and is getting leaky and showing other signs of needing a rebuild. I've heard much good about the Holley NH. I want good, clean running and a bit more power. Should I just buy a rebuilt NH? I don't want to do a mid season rebuild on the L4 if possible. Thanks.
I ran an NH for years on my 15 touring. I live in West Virginia and constantly have to deal with the steep mountains here. Wanting to be as original as possible, I acquired a brass Holley G and rebuilt it. I was amazed at the low-end power I suddenly got from the G. I've since re-built the HOlley 2-screw on my 13 and found a similar result was true. Just relaying my experience...
Never tried a Holly "G", but I have had a L2, L4, and a NH on my 15 touring. They all ran about the same but the car was easier to start with the NH.
Haven't worked on a L4, but if the inlet valve leaks so the carb floods, you can likely get a little more life out of the valve with some backyard tricks I used last week for my old NH..
I removed the float bowl with the carb in place, tried if the valve would stop the gas flow while lightly pushing the float upwards. No, it would still leak, while the position of the float when closing the valve looked right = level with the carb bowl seal area.
I took down the float and let the valve pin fall down. The conical seal area looked reasonably smooth, but not perfect. I set it up in a electric drill and fastened the drill in a vice.
With the valve rotating I smoothened the cone with first a file, then a light touch up with fine emery paper.
Back to the carb, pressed the needle valve to the seat with water pump pliers (moderately hard)
then checked again if it would stop the flow with the float in place with a light push up - it would, and no more occasional flooding from the carb
Total time for the fix: 10 minutes
The drawing in this thread shows the L4 is similar to the NH in design of the float valve:
L4 is a good carburetor. Both kinds can get leaks, so it is a toss up. Always turn off the gas when you park a T. Even one which has not leaked before can start leaking. The problem is often a bit of dirt in the intake needle and seat. Not enough to block the flow, but enough to keep the needle from seating, so try cleaning that part out first and maybe if you are lucky it will stop leaking.
Most everybody knows this, but in case somebody doesn't know it, Norman's advice is EXTREMELY important in the case of a Model T parked and/or stored inside any enclosure, especially an attached garage. The one time a speck of dirt or rust in the needle/seat causes a leak in a garage with a water heater or some other source of flame or spark, you could lose the whole house, not to mention endanger lives of the occupants! A real safety issue for sure! FWIW,.....harold
I have never replaced a Model T carburetor needle and seat. Similar to what Roger said, I polish the needle with emery in a drill press, the put the needle in the seat and gently tap it with a small ball pein hammer.
You will not notice any noticeable difference in performance, whether its an L4 or an NH.
Another place an L-4 leaks is at the bottom of the bowl around the depression for the drain cock. That's where mines leaking now, it's a high stress area and it cracked. To fix that you need weld the crack closed, but you better do something about the fuel residue first.
I've heard that the best overall running stock type carburetor is the Holley NH Straight Through...although it seems it's a bit cold blooded during starting, but once warm it's an even performance (idle, cruising, climbing) carburetor that even gives you a few more mph in the bargain.
If you want to compare the Holley NH to the Kingston L-4 drawings you can see it Lang's online catalog under the topic "Download".
While I am not running an L4 right now, I keep one as my backup. I have found my was car very easy to start using it and ran just fine at the speeds a T was meant to run. Your experiences may very!
Ok. Sounds like I should keep my Kingston L4. It doesn't leak when you stand there looking at it while running or not but, there is always plenty of gas sitting on the the pan beside the engine. I'm starting to get stumbling of the line. The carb is the only part of the car I've never touched. Should I remove the needle and make sure it's smooth and clean? Does the drain have to be opened to remove crud that's inside? Anything else I need to do? The car runs great at idle and cruise. Thanks again. Dave.
Ok. Sounds like I should keep my Kingston L4. It doesn't leak when you stand there looking at it while running or not but, there is always plenty of gas sitting on the the pan beside the engine. I'm starting to get stumbling off the line. The carb is the only part of the car I've never touched. Should I remove the needle and make sure it's smooth and clean? Does the drain have to be opened to remove crud that's inside? Anything else I need to do? The car runs great at idle and cruise. Thanks again. Dave.
My '15 Holley G works very well. I never touch it. They're a bit complex to set up, and you need some special tools and jigs, but once you're familiar with them, they're very reliable. The only thing I have personally noticed is the NH is a little better mileage wise.
When I park my 13 touring in the garage,I always turn the gas off,with the motor running & let it run until it quits,then I disconnect the battery.
I would rather be safe,than sorry.
I've run both the L4 and the NH on my 11 and I do notice the L4 idles better and takes less adjustment while in climbing hills BUT the NH blows the doors off the L4 at speed and climbing hills. I like the NH myself.
Richard -- You might try a Holley G, which was used '14 and later. They work really well, and a brass one would look nice on your '11.
There have been several tests over the years to compare power of stock Model T engines using various carburetors. Last year for example there was a test published in the Vintage Ford showing that the NH carburetor gave about 10% more horsepower as measured with a dynamometer compared to any of the Kinston L series. The Holley G carburetor was not much better.
Russ Potter did a much more extensive test several years ago. Russ, as some of you may know, is known as the "Carb King" because he restores all sorts of Model T carburetors and has a great reputation for doing this over the past 30 years.
Russ compared every Model T carburetor from the Kingston 5 ball to the NH on the same engine, on the same day, on the dynamometer. His results also showed the Kingston L series to be very inefficient at making horsepower and also yielding a higher fuel consumption than the Holley NH.
Bottom line the answer is yes, it is worth your time to switch to an NH. The test results from multiple studies of the subject are overwhelming, clear, and easy to understand.
Royce, do you remember the difference between the 1920 straight through NH and the later regular swayback style from the tests?
Russ said it was not much different, maybe 1/2 horsepower comparing the regular NH to the straight thru. I wish Russ would write an article about it for the Vintage Ford.