VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 1935 Carburetor Question

Hello all. I have a 1935 QC (1.5 ton truck) with a 207 in it. When I got the truck a couple years ago I went through things to get it running as good as possible. At that time, I found that turning the idle mixture screw on the Carter W-1 (three screw air horn. Two screws on the bowl cover, no tag) had no effect on the idle whatsoever. After talking with Carbking I got a rebuild kit for the carburetor and followed the detailed instructions to rebuild the carb. After reinstalling the carb, I find the same results, I can turn the idle screw all the way in, and the motor just keeps purring along. I decided I should check for vacuum leaks and I did so using unlit propane all around the carburetor, intake manifold and the vacuum connection to the spark advance. There was no change in the idle, except for when I direct the propane near the air cleaner which caused the engine to slow quite a bit. I also found, that when I completely remove the idle adjustment screw that the engine dies. I’m not sure where to go from here, I would like to find a different carburetor to try on this I guess. Anybody have any thoughts as to what could be going on?

How did you clean the carburetor while it was apart?

Mike

Hi Phyrphighter (nice spelling variation 🙂)

You have a restriction in the idle circuit, and if you didn't remove any of the small plugs driven into the ends of the idle passages during cleaning, you will need to.
Removal isn't easy if you want/need to reuse the plugs, but I've done it.
You will need a set of gauge sized drill bits (the longer the better) to select the right sizes from and carefully run the bits into the passages BY HAND.
There is a small brass orifice in the middle of the top cross passage that you will need to be careful about as it is a much smaller diameter than the passage itself.
I think the drill size for that is in the Carter specs for your carb.

Did you install a new idle jet?
If not, did you swell the inner end of the old one slightly so that it seats and seals when reinstalled?

Even after all this, I had to raise my float level nearly a 1/16th of an inch to make my idle circuit work properly with the gas I get at the pumps today.

Hope this helps
Good luck 🙂

I soaked the carburetor in a bucket of carb cleaner then blew the passages out with air. I did pass a very fine wire through any passages I found.

I tried that too... several times over.

And I tried lacquer thinner.
And just about everything else I thought might work.

Nothing improved until I did as in the previous post.
A small amount of rusty stuff came out with the drill bits.
It really didn't look like that much.
But the change was huge and immediate.

Tweaking the float level put the icing on the cake so to speak.

Thank you for the thoughtful post. Although I have rebuilt carburetors before, I have to admit the W-1 intimidated me a bit. I did replace the idle jet (I believe that was the one that I had to slightly open up with an ice pack to be sure it would seal). I was afraid to remove some of those plugs because I would be left with no carburetor at all and I don’t know what to replace it with. I am certain I did not run an indexed drill through any passages. For now, I have just left the idle jet all the way in as it doesn’t do anything. The truck runs really well I just have to believe the performance would better if everything was correct.

I did not realize that raising the float would change the idle circuit.

You have given me things to think about. I may have to risk making a mess of the carb and getting behind those plugs to clear the passages.

Well, I searched all I could find for an index size of a drill that might help clear any blocked passages in the ldle circuit of my W-1 but that information does not seem available. All the rebuild instructions I can find for that just mention cleaning the passages with compressed air. I did take the plugs and needle valve out of the low speed circuit and a small wire ran through them freely. I reassembled everything and still the low speed needle valve does not seem to make much if any difference whether it is open or closed until I take it out completely in the engine stalls. I think I’m going to have to try to search for some kind of a suitable replacement carburetor for this 1935 207. For the most part, it runs OK now except for a backfire through the carb when I open the throttle too fast. I have checked the timing and the BB lines up with the pointer at idle with the octagon selector at 0. I have the octane selector set at. + 8 advanced due to the octane in our modern fuels.

I will update if I ever figure out what to replace this carburetor with.

Call Dean Echols in AZ. He rebuilds 1932-49 Carter W-1 carbs. He will help you out. He is listed in the G&D mag in the services offered section.
1-928-710-4325
deanechols38@gmail.com

If the throttle positioner screw (a.k.a. curb idle screw is turned too far clockwise (in), no adjustment of the idle mixture screw will have much, if any, effect on the running of the engine.

Jon

What he means the throttle plate is open past the idle circuit and engine running on the slow speed circuit.

Those pesky plugs:

There were a number of passage plug used in the various Carter W-1 carbs.

Most of the pressed-in plugs were soft copper, which was later change to soft aluminum.

The threaded plugs are brass.

ALL OF THEM ARE AVAILABLE!

We do not include them in the rebuilding kits for several reasons:

(1) It would drive the price of the kits higher
(2) Generally, only one of the pressed-in plugs is ever necessary, and it less than 50 percent of the time.
(3) If they were in the kits, many would decide to change them without knowing how, and damage the castings. Have been there with Stromberg main metering jets. I had to produce an oversize plug to allow folks to fix the castings they damaged when we placed the double D main metering jets in the kits and folks tried to change them without the proper socket. (Hint - needle nose pliers are useful for pulling needles out of noses, NOT for removing main metering jets!).

While not in the kits, they may be ordered with the kits.

So, you want to remove the plugs.

Carter offered a special tool T-109-43 to make life easier. This tool may be seen here:Carter special tools

Scroll down until you see the numerical listing of tool pictures and look for T109-43.

The special tool is quite useful if one does many Carter carburetors, BUT NOT NECESSARY!

If you only do one of these occasionally and don't collect carburetor tools:

(1) CAREFULLY, grind off the head of the rivet plug, so the plug is flush with the casting
(2) Drill a hole throught the center of the plug for the smallest not-so-easy-out in your collection of not-so-easy-outs. The passage is 0.125 (1/8th inch), so the drill and not-so-easy-out should be smaller. Drill completely through the plug (depending on how well it was seated, about 1/8th inch)
(3) CAREFULLY, use a small hammer to seat the not-so-easy-out in the plug.
(4) Remove the not-so-easy-out resisting the temptation to try to remove the plug.
(5) After everything that heat can damage is removed from the casting, heat the area of the cast iron with the plug with an acetylene torch, until that portion of the casting is cherry red. DO NOT QUENCH, ALLOW THE CASTING TO COOL NATURALLY.
(6) Insert the not-so-easy-out, tap with a small hammer, and then remove the plug.
(7) Clean the passage. Since the original diameter was 0.125, best to least a slightly smaller bit AND ROTATE BY HAND - NO DRILL!

In a pinch, remember that both Rochester and Stromberg used lead balls instead of tapered plugs. If you fish, open your tackle box, and pull out a small split shot sinker slightly larger that the passage, and using a punch and hammer, insert it into the casting.

Jon

And that, my friends, is why he is the Carb King.

Mike

Thanks for the further suggestions. After reading loads of material on the Carter W-1, I also started to think that maybe the idle screw could be too far out causing the throttle plate to be open too much for the low speed air mixture screw to be effective. I will be pulling this carb and going through it thoroughly in the next couple days to triple check my previous work and I will post after. Thanks for the suggestions / education.