VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 36 carburetors

Our new to us 36 Master is having fuel problems. So I am going down through the list of potential fixes eliminating the easy ones first. The car has a 334S on it now. I noticed in the parts for sale section there was a 335S for a 36 truck and standard. So I bought it as a spare. The engines are rated at the same HP so there should not be a huge difference in much, right? I suspect the performance curve on the truck carb should be toward having more torque at a lower RPM but other than that I would not think it would be too noticeable. Both of these have been rebuilt. Am I on track with my thinking or totally out in left field? The Carb shop says these may not make good drivers.

I would first verify that the fuel pump it operating correctly. The 335S fits both passenger and truck models according to the info I have and is an "economy" carb. Info is from a G&D article by Forest "Chip" Sweet AKA Chipper on Chat and Doyle Stokes (VCCA Carb. Technical Advisor). That is IF it was rebuilt to original specs. It may help if you you tell us the symptons of the problem.

Sorry, I did not realize I was in the parts wanted forum when I posted the question. I will post in the 33 - 36 forum.

No problem. Now moved.

Look on the side of the carburetor to see the numbers. Since 1936 is a split in half year there are two kinds. Both will so call "fit" but will not "work" properly on the car/truck. Early 1936's have the 319S and Late 1936's have the 334S. Check to see if your car/truck (master) is a early or late '36. In order to have the "proper" carburetor on it. There are some who say that the 319S can be replaced with the 334S but I am not one of them.

Also low gasoline mileage and engine failure may be caused by installing a carburetor cover for 1935 and early 1936 (319S) car on a carburetor for late 1936 car (334S). These early model covers (319S) will fit the late 1936 (334S) carburetors and vice versa and are the same with the exception that the 1935 and early '36 (319S) covers are vented while the late 1936 covers(334S) are not. The 1936 float bowl covers must not be vented and the gasket seal between the float bowl and cover must be air tight.

On the other hand, if a float bowl cover for 1936 car is installed on a carburetor for 1935 car it will not be possible to start the engine because 1935 bowl covers must be vented.

If these covers are switched the car/truck will not start or run very poorly.

Hello Terrill, I think the block is dated February 1936. The brass tag on the carb says 334S. Still finding little issues, but not the right combination so as to get it back to a nice running reliable car. I have had it there a time or two but then something else comes up and suddenly it isn't.

Please note that your "Octane Selector" located on the side of the distributor plays an important part of the overall performance on this car. (the thing that is a knob to the rear of the distributor.) The car is controlled by three important spark advance systems. The Octane Selector should be put on advance 8 to 10 degrees for the gas we have today is aprox.80 octane. Putting it there should give you fast starts (easier starting) and much better running ... The vacuum advance pot located in the same area should pull the entire distributor around as you give it a punch of gas. It is also important the place oil or a light grease on the "slide" under this area. If the slide sticks or does not move it can not advance properly. If the pot does not work it needs to be replaced. Finally the weights inside the distributor under the distributor plate need to be checked to make sure that they are not frozen in place or have a broken spring. Removing the base plate and twisting the outside of the distributor to see if they move. Sometimes they stick after setting all those years like your car did. While there are other things you will have to check out...I found these items improved my motoring a great deal.

Carter was the first, in February 1936.

A much better replacement would be the 569s.

Jon.

What else changed?

The usual reason to seal a float bowl, as I understand it, is because you vented the bowl inside the air cleaner. It has to be vented somewhere or the fuel couldn't flow out.

With the bowl vented to the outside, as the air filter becomes more restricted, the outside air tends to "push" on the fuel, richening the mixture.

On more modern carbs the bowl is vented inside. It is usually that diagonal pipe sticking out above the choke plate.

I didnt think Chevrolet did this until the pipe became visible in the 40s. Did they acomplish it some other way back in 1936?

I don't understand everything written in this thread.

Both 319s and 334s used the exact same bowl cover (146-34) and dust cover (118-16s).

The major differences in the two carburetors:

319s airhorn 6-157s (balance vent ABOVE choke plate)
334s airhorn 6-181s (two balance vents, one above, one below choke plate.

In both of the above, vents are internal (below air cleaner).

319s metering rod 75-155 (0.069x0.053x0.042)
334s metering rod 75-171 (0.068x0.057x0.040)

The 334s metering rod is richer on both high vac, and WOT calibrations, and significant leaner in the mid-range. This found to not be an improvement, and replaced with 75-176 (0.069x0.056x0.042). Note these are the same calibrations on both high vac and WOT, but 0.003 leaner than the 319s midrange and 0.001 richer than the 334s original release midrange.

Idle port - initial release of the 334s carried the same idle port specifications as the 319s, but subsequent releases of the 334s has the lower idle port increased from a number 54 drill to a number 52 drill to provide a more uniform idle mixture discharge.

One issue raised in the Carter service bulletins was that the vacuum supply for the distributor advance could become partially clogged, and any rebuild of the 319s should include removal of the three (3) rivet plugs in the lower casting, a good cleaning, and replacement of the rivet plugs. The bulletin does not include the 334s, IMPLYING that this was changed. The Carter specification sheets do no give part numbers for the main body, and I am too lazy to pull the actual drawings off of the 500 foot rolls of microfilm; so cannot state for certain that a change was made.

Jon.

One other item:

Beachbum - the 335s is SIGNIFICANTLY SMALLER than either the 319s or the 334s. This is quite evident if you turn both upside down, open the throttles, and look through the venturii.

The 335s will significantly impair highway performance on the Master.

Jon.

Carbking: Thanks for posting that!

I agree, thanks for the tips and insight. One mistake I may have made is I did not have another cover gasket when I pulled the float cover off. The float was WAY off in both directions. Probably 1/4" off on the closed (no flow side).

The 1936 engines were purposely "throttled down" to prevent overspeeding. Several improvements increase lower speed power but a smaller intake manifold and carb. lowered high speed power. Horse power at maximum engine speed was reduced from 80 to 79 despite redesigned combustion chambers, higher compression ratio, etc.
Described in Engineering manual as "For 1936 the power is governed to produce the same maximum car speeds as 1935 but the torque is increased to provide more pulling power. The slightly smaller intake manifold is used in 1936 to govern the high speed"........The 1935 and 1936 cars had the sme top speed of around 77 MPH but the 1936 had better low speed high gear power.

If you check the service bulletins for 1936 there is a reference to always change the float bowl cover gasket when the cover is removed . It also states the cover is .018 bowed (convex) in the center to give proper contact on the gasket for a good seal. Just happened to run across it while researching accessories.

I have some new bowl cover gaskets from kits that I broke-up...in fact I have a 1936 genuine carter kit. Let me know if either would help.

I saw that note in the manual as well. That's why I mentioned it to see if it was truly something I needed to address, or if it was overcautious reaction on their part.