Zenith carb seems positional?Help Needed.

[ArticiferTom]

Happy  Holidays  All

  My 4cyl 1931 Plymouth engine 196ci engine in'31 Dodge /Graham has a replacement zenith updraft carb on it . I have been fighting to get the engine to run consistently uphill . I eliminated  fuel dirt and rebuilt fuel pump diaphragm . I cannot find numbers on carb believe it to be 267 or 14966 . It starves out of fuel on acceleration on grades , can not restart till back down . I removed bowl and clean inside with cleaner .

   Could this be an adjustment issue ?  Does any one have set up adjustment  . Or maybe vacuum issue ? What would vac be on this engine ?  Do not if truck ever worked proper ,I just got this year .

                                          Thanks Tom

Edited December 26, 2015 by ArticiferTom (see edit history)

[keiser31]

You might check between the manifolds and the engine for a hole in the manifold. Sometimes there is a hole there that someone took the plug out of or failed to install a plug in. It may take a small lirror on a stick and a flashlight to find it if it is there.

Edited December 26, 2015 by keiser31 (see edit history)

[vermontboy]

Perhaps a low float setting?

[carbking]

From about 1933 to about 1975, Zenith placed the identification number on a round tag riveted to the body of the carburetor.

 

From about 1975 to about 1980 Zenith STAMPED the number on the edge of the mounting flange.

 

From about 1980 and newer Zenith STAMPED the identication number in a small semi-circle (small, as the entire semi-circle may be hidden by a single garden pea!!!), generally on the bowl cover.

 

I have no specifications on the Zenith 14966 carburetor.

 

The late model Zenith universal replacement carburetors make an excellent inexpensive replacement IN SOME INSTANCES! We have sold hundreds of them ourselves, but we always ask the question "What type of terrain will be vehicle be driven over"? WHY do we ask this question? Because the cheaper versions of the Zenith replacements have no power circuit (a circuit separate from the main circuit that augments the fuel going over hills). If the customer states that the vehicle will be used on relatively flat terrain, we suggest the Zenith. If the customer will be using the vehicle in hilly or mountainous terrain, then we suggest the customer purchase the much more expensive Carter BB or Stromberg SF series.

 

Having said the above, BEFORE throwing rocks at the carburetor: check cylinder compression, and if good, then do a complete engine electrical tune-up. Another good check is a fuel pressure gauge AT THE CARBURETOR to make sure the carburetor is kept full of fuel when the issue occurs.

 

As to adjustment: if the Zenith is equiped with an externally adjustable main metering jet, the suggested INITIAL adjustment is 2 1/2 turns. The final adjustment to be made based on how the engine performs at cruising speed on level terrain.

 

573-392-7378 (9-4 Mon-Tues central time) if you wish to discuss further.

 

Jon.

[ArticiferTom]

Thanks All .

   Did a visual with mirror of manifold and carb . No unplugged holes found . Did find a number stamped on flange of carb  12-91 . I'm attaching pic and will get a pressure gage and vac gage  to check . It runs and idles so great even backing up  300' driveway fast ,is no trouble .

  If you could point out MAIN screw Jon , I would appreciate . One pic shows with temp. fuel filter added ,and inside when cleaned bowl of white corrosion .

[carbking]

Tom - the 12-91 is a date code, the carburetor was manufactured in December 1991.

 

The adjustable main jet is a "T" handle that is visible in the second picture. It screws up into the bottom of the carburetor bowl at approximately a 45 degree angle.  It also appears in the first picture, but that pictures displays upside down.

 

Something else to check, since this is one of the Zenith universals with the adjustable throttle; is if the throttle plate on the carburetor is moved to the wide open (vertical) position by the throttle linkage from the footfeed. If not, the clamp nut on the throttle shaft may be loosened, and the position of the throttle arm adjusted.

 

Jon.

Edited December 26, 2015 by carbking (see edit history)

[Spinneyhill]

inside when cleaned bowl of white corrosion .

 

 

It is my guess the white corrosion could be throughout the carb. I have seen it before in an updraft carb. on a 4 cyl flathead '50s boat motor where the boat is stored over winter coz the lake it lives on freezes. Get the solvents and compressed air into all the passages and jets you can find. The boat's symptoms were the same: idled well, ran well at slow speed but not at higher speed under load.

Edited December 27, 2015 by Spinneyhill (see edit history)

[ArticiferTom]

Thanks All ,

        Did some of tests recommended . Compression all cylinders 60-62 PSI , plugs showed black carbon . But the vac was most interesting .At the single wiper removed hose read 8 "Hg, but during engine revving it fell to 4-5 "Hg . Then removed metal tube at intake manifold put vac gage to port and engine went to a high idle, pushed throttle lower and was getting a reading of about 18"Hg vac .was not able to rev engine from position and fingesr were freezing  . I think, I must look for a line leak . What would normal vac be ?  

   Jon , attached is a pic from my owners manual of carb not sure if same for six cylinder  . It looks like a backwards Chevy RJH-08 . An article in DBC magazine show same truck with similar, but could not see pump on it, and listed as DRJH-08 . Any input ?

 

                                                                   Tom

 

[carbking]

According to the factory Carter literature:

 

1929 4 175 RT-08 130s

1929 4 196 RJH-08 142s

1930 4 175 RT-08 156s

1930 4 196 RJH-08 142s

1931 4 196 RJH-08 171s

1932 4 196 RJH-08 228s

 

Although very attractive in appearance (black body, brass bowl); none are much of a carburetor. Pretty much a pain in the (insert some portion of anatomy here )

 

Good luck on finding one with a tag, as the originals were red cardboard. Some of the service replacement units produced in the mid-1930's do have a brass tag.

 

Just for the record, Carter produced 22 different TYPES of the brass bowl carbs (RT-08 is a type) in approximately 250 different models.

 

Carter listed some other models (the type DRJH-08 included), but the factory literature indicates these were for export. Cannot tell if they were also used on domestic models. The ones listed above are shown for domestic models.

 

Jon.

Edited January 3, 2016 by carbking (see edit history)

[Spinneyhill]

Another dumb thought... I am full of them! Does the fuel pump have a glass bowl? I, personally, have managed to warp the top cover of such a pump so it doesn't seal against the bowl. A little fuel is delivered but when the demand increases it is not enough. I have also noticed some of these are warped as the pot metal breaks down.

[hchris]

The vac figure at idle would be about 18 - 20"; certainly if you have a vac leak the engine will not run well at all.

[ArticiferTom]

Just an update to finish this thread . Found vac leak at wiper ,to large tubing . Rebuilt needle and carb adjusted with vac . Still ended in starving for gas . Found 1/4" fitting at tank blocked with heavy rust ,not making or showing at filter . Starved out on acceleration . Removed tank as noted in new post . Today final hooked up tempory can and was able to that a drive ,plus make it back home 3 miles . Awaiting tank now . Truck ran good  up hill and long accelerations ,did have small boiling over when got back . I think I need to do flush cooling system . Cap removal showed brown slime in antifreeze on cap .

  Thank all for help !     Tom

[Spinneyhill]

Might that brown slime indicate a little oil in the water? My first car, a Morris 1100, usually had whitish slimy foam on the inside of the oil filler cap on the rocker cover. I think it was condensation (water) in the oil.

 

Did you leave the water level about 3" below top of radiator? The manual says to do that for my DC and if I fill it further, it comes out of the breather (or out of the cap if it doesn't seal properly). Mine also sometimes used to burp out of the cap: I am not sure why but it might be something to do with the thermostat not having a tiny bypass hole and when it opens a burp of air comes out. This occurred to me after refilling the cooling system after work - it blew green coolant over the paint.