The Stovebolt Site Forums The Shop Area Engine Shop 1953 Chev 1/2 not idling

Hello All,

I got a 1953 rebuild Chev 1/2 ton and trailered the truck home (1100km). It run good when i checked it at the purchase location, but seemed to sputter when in higher engine speeds.

We dismantled the carburetor (Rochester BC, auto choke), cleaned all and got a rebuild kit. The engine idled before, but I feel the idle speed was set with the accelerator linkage, not with the idle screw.

Now we have no idle, but the truck runs on higher engine speeds, but not at idle.

The passages are all free and we are scratching our heads.

Any advise?

Cheers, Joerg

The first thing to look for is vacuum leaks. Use gas from a Propane torch (unlit) and move the tip around all the gasket surfaces like the intake manifold to cylinder head junction, carburetor base, and vacuum lines that might be attached such as the windshield wiper motor under the dash, etc. If the engine smooths out or speeds up when the gas gets sucked into a leak, you've found the problem. Also check the ignition timing- - - -late timing makes it hard for an engine to idle properly.
Jerry

That carb has a tube cast in the air horn across the top of the carb. On one end of the tube is a tiny core plug. Occasionally that plug falls out or is blown out when cleaning the carb with compressed air. That will cause a massive vacuum leak with symptoms you describe.
It can be filled with e-poxy glue or similar.

George

We are kind-of in winter mode (or mood). The truck is in my unheated, but above freezing shop right now.

Last week, we tried to set the timing and thought we had all aligned, but then we got a back-firing once through the carb and haven't touched the darling since, just to ugly to work on it right now.

We set timing with the valve cover off.

We will get at it again, probably in February or if we feel ambitious in December and get it in the heated shop. More then.

Oh, btw, the distributor has electronic pickup.

Can we check the right timing through the electronic points? I use to work with natural gas pumping units, ford 428, Chrysler 318 etc. and was relatively good at them, but that's 30 years back and memory fads away.

The flywheel has no other timing markings than the dot, beat or whatever you call it, right? One should be able to mark the BDC degrees by the teeth on the flywheel with a proper marking or not?

Cheers, Joerg

That "electronic pickup" is probably a "Pertronix" system. They come in two types- - - -the ones that have failed, and the ones that will fail soon. I'd strongly advise acquiring a spare distributor with conventional points, and keep it in the truck so you can get home when the system craps out a long way from home. Those things are about as welcome among most stovebolters as a good case of hives!

Most flywheels with just a dot and no other markings have the dot positioned at 5 degrees before top dead center. If you have a strobe light, just align the dot with the pointer with the engine at a slow idle. Some people choose to disconnect and plug the vacuum line at the distributor while setting initial timing. The dot and pointer was originally intended to be used setting timing with the engine stopped, using an ice pick type test light.
Jerry

Thanks Jerry & others,

I can get a new Zenith 28 carb. about 400km away from me or a old Carter YF from the internet & rebuild it.

Is the flange bolt pattern the same on Ford, Chrysler (Jeep) or Chev. versions of the YF? I am talking about the flange to mount the carb on the intake manifold.

Time is not really the issue since I will not drive the truck before spring anyway.

Joerg

Lots of Carter YFs interchange with lots of different makes and models.

My truck had a cobbled together Carter carb with parts from an early 50s Jeep and a mid 60s Jeep. Of course the metering rod was not ideal for the 216 Chevrolet.

Talk to Carbking and locate the CORRECT Carter YF for your specific application and then rebuild it. I did that and the Carburetor has functioned flawlessly for 4 years and over 10,000 miles.

The Carter YFs all look about the same but they are not the same. Here is my correct carb next to the incorrect one. You can see the slight difference in the casting just behind the fuel inlet in the first two pics.

Most (maybe all) YFs have a slotted base plate that will fit either the 216 intake manifold with the close-spaced studs, and the wider spacing of the 235 and 261 engines. With a spread of 40+ cubic inches among those engines, there can be a wide difference in calibration of a specific carb. The "one size fits none" principle applies here!
Jerry

Jerry, I have a Carter YF 964S carburetor on my 216 that will definitely NOT mount on a 235 manifold. And from what I know about the YF2100 series is that they will ONLY fit 235 or 261 manifolds. But I believe the throttle bodies will interchange between the bowl sections of the two series YFs. I believe the venturis are sized differently as well. But what you say about calibration differences is true. There are no "one size" carburetors (that will work anyway.)

We pulled the truck into our shop and took the distributor out.

The drive gear was loose on the shaft and we took the pin out and replaced it. It (the gear) is now tight on the shaft.

We set the flywheel to the beebee, 5° BTDC. Have the rotor pointing proper, 5.00.
Turned the clamp bolt holding the advance to the stem so it can be accessed from the front, where a person can see what he is doing.
Tested this many ways and we have good spark on all plugs.
Compression is 142-160.
Attached the spark plug wires by firing order.

No vacuum leaks all possible vacuum ports are closed!

Tried to start, but only get the somewhat try of running. No thorough running cycle.

The spark plugs where wet, soaked, but no running.

We are totally frustrated now and I will order a new Zenith 28 from BC.

I am away for two weeks starting tomorrow and we will get to it again mid December.

BTW, I have a GMC with a 235 from 54 and we tried to get the distributor out of it to use it for mechanical points, but the stem doesn't come out of the block.

Can this be a O-ring holding the shaft in or could there be a setscrew in the second grove holding it in?

Joerg

You sure you aren’t 180 degrees out? That BB comes around twice. Have to make sure it’s timed to BB with #1 near TDC on ~compression~ stroke.

Hold your finger over #1 plug hole and have a buddy crank it. When it pushes your finger off the hole you are close. Then look at rotor and see where it’s pointing.

Sorry, one thing I didn't mention, we took the valve cover off and got play on #1 in and out rockers.

I cleaned the plugs and noticed that the connector (metal clip) that actually goes on the spark plug where deep in the rubber connector. I pushed the clip out all the way, pushed it on to the plugs and than pushed the rubber over. We gone some running, but not a good fuel supply through the carb.

Ordered an new Zenith 8 now.

Joerg

Shouldn't be any kind of O-ring holding the distributor in. GMC and Chevy distributors work the same. I have a tall (1954 or later) Chevy distributor in my '52 (came with a short distributor) GMC.

Figured that, we had -18C yesterday and things don't want to move at that temperature very well.

Cheers, Joerg

Is that new Zenith 28 an actual Zenith? Or one of the repops that looks like this:

https://daytonaparts.com/m/replacement_carburetor_chevy.html

Hello again,

Sorry for the wait, but I was away for a few weeks and got the new carburetor today. I guess it is a Daytona UN2, I am confused why it was sold as Zenith model 28 but what I actually got is a Daytona UN2 .

Here are some pictures.

I assume you fellows will have some comments.

Time is tight right now to get this unit installed and the truck running, but I update as things unfold.

Joerg

I think "Daytona" is owned by the heirs of P.T. Barnum. It's a poor quality copy, not even a "clone" of a real carburetor.
Jerry

Now I know

KLH, thanks for the fix!

Generally, the imitations are advertised as "Zenith-like" or "Zenith-type" or ???, rather than "Zenith" by the more "reputable" dealers (if any dealer selling this stuff can be called reputable).

I think I would look at how it was actually advertised, and if advertised as a Zenith, back it would go!

Jon

I seem to remember a member getting one of these Daytona replacement carbs a while back.
There was some ongoing reporting of performance.
I cannot find the thread.

Here is the thread I recall: https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1544528/1

That said, if it was advertised as an actual Zenith, you got scammed and should get your money back.

I would say 'hold your horses'. The carb looks well build, went on fine and the sweet girl hums now like a kitten. I am happy, probably not to the standard as some, but fine enough for the girls I go with.

Next steps the adding a canister type oil filter.

That is great news, glad for you to have some success.

How's the full throttle load pulling ability, and throttle response? How about gas mileage?
Jerry

Dear Jerry,

We are still working on: a) choke control cable for the now manual control verses the Rochester automatic control, b) clean & powder coat an old oil bath air filter to fit the Daytona 'Zenith Type' carb..

Then, on a nice, sunny, warm day (probably non around north of the 49th for some time), we will do a long drive, but I will not post mileage numbers etc. since we don't have the scientific measuring equipment that would match your high standards.

BTW, the old Rochester BC and a Carter I have will be rebuild by a professional to try next spring or summer.

If I would need sophistication, digital readouts, air-condition (other than roll-down windows, I would have bought a new 3/4 ton Chevrolet Silverado to replace my 2009 to pull my 14,000 lbs trailer, but I wanted one that (nearly) matches my age and aches and let the 2009 pull the trailer.
Joerg

I'm right there with you Joerg.

If I wanted a truck with all of that crap on it I had bought one. I just made a 40 mile trip with a load of firewood in my 75-year-old pickup.

My 1956 Cadillac is the most "modern" vehicle I own. By that, I mean it has power windows power brakes power seat automatic transmission and air conditioning.

Small improvement on my 53 Chev.

My son decided that the exhaust system was crap and he is welding me a lower grade stainless system since the muffler itself is mild steel.

here the first stage from manifold to muffler.

If you are going to use a fiber donut in that flare you might consider welding a short section of tubing into the flare to support and align the ID of the donut. I’ll call it a fire ring but not sure that is the correct term.

Chuck

You are correct, Chuck, we had this done already, just laying under the truck right now.