MTFCA Forum

I have a 1922 Touring car that I have been trying to get smoothed out and get rid of a miss or hesitation. I met a bunch of guys yesterday at an event and even followed up with a phone call today with one of them and he has been great swapping pictures and walking me through some things. I have the major miss taken care of but it still seems to be hesitating a bit and he suggested adjusting the mixture while I was driving it. I told him I could not reach it while I was driving because it was up against the firewall under the dashboard. This led to a discussion and us looking for pictures of what a 1922 dashboard is suppose to look like and if I was missing some parts. So far I cannot come up with a good picture of how it is supposed to be assembled and if it is supposed to come through the dash for access. I have a hole next to the choke that someone has a switch installed that is not wired to anything. Maybe this is where the Mixture knob is supposed to be? There is a black bracket attached to the adjustment rod that looks out of place. Can anyone shed some light of possible a photo as to how this is supposed to be assembled? What am I missing? Is the adjustment know supposed to be where the mystery switch is? Thanks in advance for any help!
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John

that thing to the right of the switch is where the choke pull comes through. The fuel richness setting is generally correct.

Now, for the reality of it. I do not know what is making your car miss. With that out of the way I can tell you that the NH, while primitive, is adequate for idling, accelerating, and cruising all on the same richness setting once the car is warmed up. Lots of folks are going to show up to tell me I'm full of it, but it is true. When clear and clean, the low speed bypass circuit is generally running the car until about 20 MPH and at that point the pressure through the venturi is at the state where the main jet will take over.

So, here's the meat/potatoes of it all: if the low speed circuit is clogged or restricted, you can set the richness such that it will run the car, but when up to speed will require more fiddling to adjust to the different circuit taking over. A wobbly/sloppy fit of the throttle shaft to the body and the attendant vacuum leak does not help either. Alternately or in addition to this, the float level may be wrong, keeping the fuel either too high or two low at the main jet and thus altering the mixture at different speeds.

If indeed your miss can for certain be attributed to your carb (and I don't see any evidence to support that conclusion at this time) then a complete rebuilding by someone competent in the trade will solve your problem...and after that, no fiddling required.

Myself, I'd be inclined to make SURE the coils are rebuilt and perfect and the timer and timer wiring is either new or up to snuff first.

Welcome to the forum

Here are the Ports Scott is talking about.. I had to 'Clean them' on the '13 I was working on.. Idle and runs at the same mixture now..
The hole on the 'End' is a plug that needs to be drilled out to get the debris out of the passage after you clean the 'Twinn Holes' out..

Cap

Instead of replugging that end hole with a new chunk of brass, I use Stan Howe's method of tapping the hole with a bottoming tap and putting in an 8-32 Allen screw, easily removed for future cleanings. Of course, once you've cleaned the passages they probably won't need it again during your lifetime.

Yes, definitely send the coils to a specialist to get them squared away. Any of the coil guys on this page will make them sing: https://www.mtfca.com/model-t-ford-suppliers/
Ron did mine and they are gorgeous.

I must be missing something! There is no Ford mechanism that I know of to adjust the mixture from the dash. Scott indicated the choke pull, but the mixture control is achieved by turning that bent loop of wire at the FIREWALL. Your loop looks to have been held captive by that bracket thingy holding it in a fixed position. It is not needed if the split brass nut on top of the carburetor is tightened to hold the needle in the position required.
It is difficult to reach while driving, and possibly dangerous to attempt doing so. I do any adjusting in the workshop, and as Scott indicates, this is generally satisfactory for road use, with little, if any, need to tamper with it further. Others will disagree with the last bit.

Allan from down under.

Scott_Conger wrote: ↑

Sun Aug 15, 2021 5:52 pm

John

that thing to the right of the switch is where the choke pull comes through. The fuel richness setting is generally correct.

Now, for the reality of it. I do not know what is making your car miss. With that out of the way I can tell you that the NH, while primitive, is adequate for idling, accelerating, and cruising all on the same richness setting once the car is warmed up. Lots of folks are going to show up to tell me I'm full of it, but it is true. When clear and clean, the low speed bypass circuit is generally running the car until about 20 MPH and at that point the pressure through the venturi is at the state where the main jet will take over.

So, here's the meat/potatoes of it all: if the low speed circuit is clogged or restricted, you can set the richness such that it will run the car, but when up to speed will require more fiddling to adjust to the different circuit taking over. A wobbly/sloppy fit of the throttle shaft to the body and the attendant vacuum leak does not help either. Alternately or in addition to this, the float level may be wrong, keeping the fuel either too high or two low at the main jet and thus altering the mixture at different speeds.

If indeed your miss can for certain be attributed to your carb (and I don't see any evidence to support that conclusion at this time) then a complete rebuilding by someone competent in the trade will solve your problem...and after that, no fiddling required.

Myself, I'd be inclined to make SURE the coils are rebuilt and perfect and the timer and timer wiring is either new or up to snuff first.

Welcome to the forum

Scott,
Thanks for the reply. So far I have went through the timer system with the help of new friend who walked me through taking it off cleaning, inspecting and reassembling. The timer is a New Day and was very dirty inside. I cleaned it and it looks like new now, no pitting. This took most of the miss out of it but still feels like it is hesitating when I try and accelerate either in neutral or going down the road. Bill suggested it may be running lean and said to adjust it while running down the road. This brought up the conversation that the adjustment is not very accessible by the driver while driving. He has a 1926 and can adjust his carb from his choke pull I believe. I seen a couple pictures of my age car that looked like there was a knob about in the same area that I have the mystery switch to nowhere. Additionally the black bracket hanging off the edge just didn’t look like a factory part. Your point about the carb is a good one. I made a very slight adjustment rich while idling in the garage and it started chugging. I went back to center then slightly lean and it started chugging so I put it back to where it smoothed back out. I’m not sure how sensitive these carbs are. As far as the coils go I rebuilt these coils a couple years ago when I bought the car and tuned them with my ECCT. Just for giggles I put a second rebuilt set in and it did not change anything. I tested the originals and the caps (all new) and timing tested excellent. Soooo...all that being said I just want to reiterate that although I have owned this car for 2-3 years I am a total noob with the T so I appreciate any advice. I’m sure I will have an ah-ha moment when I figure this out but in the meantime I’m enjoying playing with the car.

John, you are right about the 26-7 T's having mixture control at the dash, and earlier cars like yours, not having same. On some special cars built by the coachbuilders in Australia, a dashboard adjustment was fitted. This required a universal joint in the control rods, just on the engine side of the firewall. Some even had the in-car rod mounted high on the steering column.

Allan from down under.

Here is a cross section view of the NH showing the inside and necessary float adjustments. As the bowl fills, the rising float causes the needle valve to close, stopping the flow of gas into the bowl and preventing the gas from overflowing into the carburetor vent tubes. Of course when the car is running the needle valve is constantly opening and closing to maintain the correct bowl level as the fuel is consumed. Jim Patrick