MTFCA Forum

The things I get into! I like helping folks out but I might be out of my league on this one. A local widow got my name that I knew something about Model T's, so she asked me to troubleshoot this car. It runs pretty good for a while but then starts backfiring and ultimately quits. It has a RAJO head and a Ruxtell rear axle. Oh, and a distributor. If she decides to sell it (if the son doesn't want it) I will help her.

My guess after driving it the problem lies in the fuel delivery system. If you look carefully, you can see how the fuel line rises very sharply before it screws into the carburator. I suppose if the gas tank was completely full it might have enough head pressure to keep feeding the carb with gas. I noticed the backfiring starting going uphill, so that is what leads me to my conclusion. This is with the gas tank about half full. I don't know what kind of carb it is, but it looks like a Tillotson of some variety. The widow said it had a "Model A" carb on it and it appears that is about right.

My other question is about the oilers on the Rajo. I would assume that you are supposed to keep them filled, correct? What are the fittings on the tops of the oiler all about? There is a flip top oiler port on them and I assume that is where you add oil, but not sure about the rest of the apparatus.

Certainly sounds like fuel starvation. When I ran one like that on my speedster years ago I added a filter and fuel pump. You might want to disconnect the line at the carburetor to check fuel flow. Likewise check for a filter in the system.

The head should have heavy felt pads under the covers resting on top of the rockers. The oilers on top are cute and possibly convenient but once soaked in oil, the pads are good for many miles. Even on a week long tour I rarely added oil mid tour. There are usually no effective seals/gaskets for those covers so too much oil just makes for more of a mess.

I am relatively certain that the "thing" I see in the fuel line is an in-line filter. If the fuel has been sitting for any time at all, it may well be compromised with respect to the amount of fuel that will flow through it. Those 90 degree bends in the line don't help either.

I'd also look closely to see if there isn't a fuel pump lurking in there somewhere. The fellow who put this together appears to have been very careful in the execution of it and if there is in fact no fuel pump, I'd be a bit surprised.

Looks like a dandy of a car. Nice of you to help her out.

The carb sits to high.
The exact same problem befell a friend. With a full tank it ran fine in the flats. He had the habit of running at least 1/2 full tank around town, not aware of an issue. Hill driving even with a 3/4 full tank caused starvation during a cross country run.
There were no issues of an added filter & the cap was vented.
The obvious answer is to add a fuel pump.
Having a long history of failing pumps, I elected to fabricate a 6" extension to lower the carb & keep it gravity fed.
No more issues.

If trying more fuel in tank doesn’t work, Run a line from carb to an external gas can and see how it runs. If it still backfires, at least that isolates the problem to carb. May be float related or clogged passageways. What condition it the tank, gunk and flakes can cause problems with fuel delivery. That’s a fuel shut off that’s seen inline.

Re oilers:
The dodad on top opens or closes drip oil delivery. The front one is open. Flip the knob 90 degrees down to close off the oil flow.
Procedure would be to open during running & close when not.

I believe Walber's assessment of their usefulness & felt pad use is correct.
I removed a similar oiler on my Rajo.

According to the owner her "boys" had cleaned out the tank and fuel line, etc. so I have not gone through all that. The first thought I had was an extension from the intake to the carb to lower the carb so the gravity feed would have a chance. Of course then there is modifying the throttle linkage and all that. Thanks for the input.

She offered to pay me to "fix" this car, but I refused any money. I look at this and think to myself, "no good deed goes unpunished."

Ed...thank you
it took awhile, but I finally see the handle and you're right, it's a shut-off

Speedytinc, you didn't happen to fabricate two of those extensions, did you?

The drip oilers...

1 - Turns the oiler off & on. Currently shown in the "ON" position.
2 - Oil filler. Pump oil in there till the reservoir is nearly full.
3 - Sight glass, where you can watch the oil drip rate.
4 - Knurled nut to adjust drip rate.
5 - Looks like a lock nut to lock in the drip rate setting.

With the oiler filled, and #1 in the "ON" position, look through the sight glass #3 to see if oil is dripping. It should drip at a rate of maybe 2 - 4 drips per minute. If the drip rate is not right, loosen #5 & turn #4, (clockwise to reduce drip rate, CCW to increase), until the rate is correct. Then tighten #5 to lock in the setting. When you shut down the engine, flip #1 till it sits horizontal. The oil is now shut-off.

Distagon2 wrote: ↑

Fri Feb 24, 2023 2:02 pm

Speedytinc, you didn't happen to fabricate two of those extensions, did you?

No. I removed an oiler. It was screwed into the head, not the valve cover.
There was a tube thru the water jacket. neat idea to not have to remove the valve cover,but poorly executed.

This looks like a shortened coupling nut re-threaded to pipe on top with a short drilled bolt to attach & allow the oil thru.

speedytinc wrote: ↑

Fri Feb 24, 2023 2:34 pm

Distagon2 wrote: ↑

Fri Feb 24, 2023 2:02 pm

Speedytinc, you didn't happen to fabricate two of those extensions, did you?

No. I removed an oiler. It was screwed into the head, not the valve cover.
There was a tube thru the water jacket. neat idea to not have to remove the valve cover,but poorly executed.

If I may, I think he meant the intake extension you referred to...

"Having a long history of failing pumps, I elected to fabricate a 6" extension to lower the carb & keep it gravity fed."

Jerry VanOoteghem wrote: ↑

Fri Feb 24, 2023 2:40 pm

speedytinc wrote: ↑

Fri Feb 24, 2023 2:34 pm

Distagon2 wrote: ↑

Fri Feb 24, 2023 2:02 pm

Speedytinc, you didn't happen to fabricate two of those extensions, did you?

No. I removed an oiler. It was screwed into the head, not the valve cover.
There was a tube thru the water jacket. neat idea to not have to remove the valve cover,but poorly executed.

If I may, I think he meant the intake extension you referred to...

"Having a long history of failing pumps, I elected to fabricate a 6" extension to lower the carb & keep it gravity fed."

Thanks. I believe you are correct.

No I didnt make an extra one.
After making the first one, which needed some angle to well clear the generator, I made one for a non generator motor straight.
Each one was custom made to optimize fit & function.

If the fuel line is picking up too much heat, such as from the exhaust pipe, it can cause issues on longer drives or uphill runs, especially in hot weather. A modern needle and seat in the carburetor can also cause issues. They are not designed for low-head gravity systems.