The Stovebolt Site Forums The Shop Area Engine Shop Erratic Engine Idle

1950 217 idles somewhat rough on startup. It also will randomly increase and decrease in rpm.

New points, Jon Goodman condenser, cap, rotor, etc.

Carter Carburetor has not been rebuilt.

Engine started and ran smooth as a whistle before this problem. It became prevalent after not being started for about 3 weeks. Fuel is ethanol free.

After running up to operating temp - 30 min or so, it will not restart without a lot of fuss. Prior to this issue it would kick over at all times with the first touch of the key. In case anybody is wondering, this issue manifested itself prior to my leaving the key on and running down the battery so the two things aren't connected.

I'm leaning toward a carburetor problem mainly because all the ignition stuff checks out ok. Any suggestions are appreciated.

Difficulty restarting when hot can be a sign of an intermittent bad coil
I suggest swapping out only the coil and see if that makes the issue better
If it does not I would continue trouble shooting with the new coil and once you fix the issue then swap you original coil back In
Coils gradually go bad, so i always have a known good one in the shop ready to go for tests like this.
-s

I believe the problem is in the carb. Shut down the engine & look down the throat. If any gas is dripping into the throat you have a leaking needle & seat. What Carter carb do you have. A W-1 or YF?
George

Hahaha!

You are correct, George. You beat me to the post.

Yesterday afternoon I looked down the throat and fuel was pooled down on the intake manifold! I was going to post about it this morning and saw your post.

It's a Carter YF.

Somewhere on this board was a discussion about incorrect needle and seats being supplied in kits. What is the correct diameter of the needle and seat that I need?

Which YF do you have?

The inlet orifice should be 0.081” for the 2100s and 2101s. Should be able to estimate what size your current one is with a drill bit.

Jon G has also written extensively on a warpage issue with the accelerator pump “base” that can cause a rich condition, along with a method to correct it. If I can find that thread I will link it.

Ion G’s thread on the pump “bonnet”

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1416696/1.html

I've seen some of the YF models with .008" warpage gap between the 4 screws. That's pretty severe when you total up the area from all 4 sides. It is like having another (and unregulated) jet feeding fuel into your manifold all the time and it definitely will allow your fuel bowl to drain into your manifold when your engine is off. Please look also at the gasket between your float bowl and your throttle body (image attached). If you're suffering from the warped bonnet problem, it is likely you'll see that gasket looking wet pretty much all the time. In worst cases I've seen fuel run down the side of the throttle body and onto the heat spacer (as you can see it did in this case). The bonnet gets warped when somebody overtightens it and I've even seen one YF which appeared to have only been used a brief while...basically brand new. It suffered a manufacturing defect that was not caught by the assembler. There was a casting lump on the bottom of the bonnet which prevented it from sealing and had caused the rest of the bonnet to be warped when it was assembled. Good luck.

I thought it was the Rochester Bs that had the warped base problems

How do I know if it's a 2100 or 2101?

Yes, this carburetor does appear to be leaking from the area you describe. It isn't obviously warped but I haven't taken it apart and put it on glass. Is it possible that the gasket is just messed up rather than the body is warped?

If warped can it be repaired? Is that something a rebuilder would normally check?

Different warp. This is the base of the accelerator pump INSIDE the carb. You will have to remove the air horn (top section of carb) to see it.

The seep at that gasket is a symptom of the internal issue. Not the area or warp.

As for the number of your carb, look at the area where Jon’s pic says 3211.

The guy I talked to about getting a kit, rebuilding, etc. said they sell "new" YFs and new Zenith style carbs for this application.

I'd be willing to bet the new YF is made in China. Anybody know?

What about the Zenith carb?

I'm inclined to stick with a YF and rebuild this one but would a new one be worth it for 400?

My carb has no numbers stamped in that area.

The bowl has 0-917 stamped on it.

Base says 1-630

If it is the "new" "YF" I've seen, my opinion is it wouldn't be worth 400 pennies. As for the Zenith, CarbKing (the other Jon) needs to weigh in on that one. Who is this rebuilder are you talking to? No, in my experience this is not anything a common rebuilder would notice. They wouldn't take this much time at all and there are some people selling carburetor parts who I suspect might not even understand it if they saw it.

If the gasket between the float bowl and the throttle body is wet, there are only a couple of things that could be happening:
1. there is a crack in your float bowl letting fuel dribble down (would be rare but actually I've repaired such a problem in a YF before)
2. the "bonnet" is warped and that is letting fuel dribble into the recessed area below the diaphragm. From here, it runs through the drilled vacuum hole and into the throat of the throttle body and into the manifold as raw fuel. On the way down, it soaks into the gasket. Once the gasket has soaked up enough, it wicks the fuel to the outside of the carburetor. Nothing at all good can come of this internal warping. It happens because somebody over-tightens the "bonnet" pulling each of 4 corners down into the rubber of the diaphragm. And fortunately it is very easy to fix.

Please look at the very complicated tool I made. It is a 3 inch x 2 inch piece of nice flat poplar. I used a forstner bit (1 inch) to drill a shallow hole in it. Then I cut holes in two pieces of sandpaper...one 180 grit and one as I recall was 600 grit. I simply rotate the bonnet on top of the sandpaper until no low spots appear.

Hope this helps.

Here is what the bonnet looks like when I'm finished:

No, no, no.

Identify your YF. Rebuild it. Not hard. Way cheaper. Way better.

Post some pictures of your carb here. We can help identify.

Opinion

The new "Carter-like" and "Zenith-like" items (I just cannot bear to call them carburetors) make excellent paperweights right out of the box. Once they are dirty from trying to make them work, they make excellent doorstops.

if necessary, I can find the John Ruskin quote.

Jon.

Ya, that's what I figured. I always prefer repaired original stuff to new parts where possible unless its NOS.

This carb was operating fine since I got the truck running last May. It's only been within the last month or so that the problems developed. Because of this I tend to think that the problem has more to do with its age and deterioration rather than warpage of the body. Perhaps ethanol ruined the gaskets.

I missed earlier in the thread that you have a 216. So your YF is not a 2100 or 2101. But still worth rebuilding. Someone else might be able to advise where to find the model number.

In your 4th picture, see the flange that runs parallel to the choke linkage rod? I think on some YFs, the model numbers are stamped on there.

No, the only things stamped on the carburetor are the numbers I posted above. It also says Carter YF and Made in USA.

Above the float bowl next to the fuel inlet it says 6-1658

Not saying you’re wrong, but it’s worth some cleaning and one more look.

The 4th pic of this EBay link….zoom in really close to see the faint stamping (964s) on the VERTICAL flange.

https://www.ebay.com/itm/CARTER-MOD....m2548.l6249&mkrid=711-127632-2357-0

Thanks.

No, there's nothing stamped in that location on my carburetor.

At least it's not bumping, grinding, and shaking its booty- - - - -that would be an "erotic engine idle"!
Jerry

If your spark plugs are sooty black, you may have a hole in the accelerator pump diaphragm. This causes a rough running engine at idle from too much fuel going where it is not supposed to go.
I had that happen to me twice. I simply pulled out the throttle cable to raise the RPM high enough to burn the excess fuel and run smooth at traffic lights until I made it home.
Ethanol blended fuel is no friend of YF diaphragms.

So what model YF carburetor is this one? Was there more than one offered for 1950 216 engines?

Is it simply a YF carburetor?

I will most likely order the rebuild kit from Daytona Parts Co. unless somebody has a source for a better kit.

Interestingly, When Carter filed bankruptcy, Daytona acquired Carter's entire archive of plans and drawings for every carburetor they made until their demise in 1985.

Measure the center to center bolt spacing of your carb. It should be 2 - 11/16.

https://www.thecarburetorshop.com/Carter_YF_Chevrolet.htm

If you have a manual choke YF for a 216, it’s one of only a couple models. Buy your kit from thecarburetorshop.com….as far as I know they are the only ones who will supply the correct needle and seat. And probably the only ones who can assist in identifying your carb if you can’t find a model stamping.

Thanks JW. It is a manual choke and the mounting bolts are 2 11/16" on center.

The listing at the Carb Shop shows Carter W-1 but not YF? What's the deal with that?

I was unaware of this.

When Federal Mogul ordered the Carter Engineering Dept to get rid of all the drawings, they did; into my van.

Jon.

My records show that the 1949 carburetor used on both passenger and truck (684s type W-1) was held over on the 1950 trucks.

Chevolet did not use a YF as original equipment until the mid-1960's.

However, Carter did offer an excellent line of aftermarket YF's for Chevrolet.

Jon

So the YF carburetor isn't the correct factory carburetor for this truck. I suppose it was installed as an in-service replacement sometime during the truck's lifetime.

Without any other identifying numbers stamped on the carburetor, how do I know what kit to order?

Regarding Daytona Parts; Ron Hewitt and his son Tim own and operate the business. When I visited there some years back he told me that the archives were going to be destroyed/discarded because they had no value to the creditors.

www.daytonaparts.com

Yes, your YF was almost certainly installed as a service replacement. But if you look at the list I sent from Jon (Carbking’s) site….there are only about 2-3 possibilities for a 216 YF with a manual choke. Perhaps the kits cross over and it doesn’t matter.

I’d call Jon during the hours listed on his site. He’s the guy when it comes to Carter stuff.

The YF is excellent when properly rebuilt. Unless you really desire complete originality, I’d stick with it.

Obviously, Carter had more than one set.

As stated, the ones I got came from the Engineering Dept.

At the same time, got the factory specifications book, with all of the car service bulletins, both Carter and the car manufacturers; plus a BUNCH of prototype carburetors. And the complete Carter school material (about 2700 indexed 35mm slides).

I had previously worked with some of the Carter engineers, and put together a complete listing of Carter carbs from number 1 (not complete, as they did not start numbering until the early 1920's). I also have a fairly complete list prior to when numbering began.

One of the prototypes was the prototype for the first WCFB 4-barrel. Some folks argue which came first; Carter WCFB, Rochester 4-GC, or Stromberg 4A. Not going to argue, because I don't know. I do have both the Carter and Stromberg prototypes. To me, the cream of the prototype crop was the WCFB, but some Cadillac folks might disagree, as I acquired a set of first production Cad V-16 new old stock (both the left and the right). Also included was the 1930 Chevrolet prototype, a first production 1953 Corvette YH, and a 1966 first production Corvair YH.

Pictures on some of this stuff are on my "virtual carburetor museum" : Carburetor virtual museum

Hopefully, I will able to identify the YF (but probably not until next fall) by casting number. I started a major project of an in-depth article on the YF's sold for Chevrolet, and I have about 200 of them put away, including at least one of every from the first one through 3211. But I had to pull off that project, as I have a Stromberg project which I consider more important. By fall 2022, I should have every single Stromberg drawing, and bill-of-material that survive digitized.

Then I can start back on Carter.

Carter did make some YF carbs that were identified by tag only. Once the tag was pitched, identification is (at least right now) virtually impossible.

The 630 base that you have was used on about a dozen carbs (most of them Willys, but a couple of Chevrolet). If you will get me the number from the metering rod, I can identify it at least far enough to cross it to one of my rebuilding kits.

Jon

Well, its Sunday afternoon, and I have lost my focus (messed up some kit components I was making for ancient Buicks) so have quit for the day.

So will add a bit of Chevrolet carburetor history. If I bore you, just don't read it

Before 1923, Chevrolet used carburetors from a variety of manufacturers. In alphabetic order: Carter, Detroit Lubricator, Holley, Marvel, Stromberg, and Zenith (mostly Zenith).

About 1923, Chevrolet issued a "bid" for a carburetor supplier. Part of the bid specification was that the successful bidder would allow Chevrolet to manufacture a certain percentage of the annual usage in their Bay City plant. Supposedly, Carter was the only company to agree, and thus won the contract.

Carter was the primary supplier in 1924 and 1925 while Chevrolet used up the remaining Holley and Zenith units, and beginning in 1926, Carter was the exclusive supplier to Chevrolet through 1949.

Carburetors produced in the Bay City plant had a large "C" cast on the side of the cast iron. These carburetors, while almost identical to the Carter versions, carried a tag with the Chevrolet part number rather than the Carter number; and the internal parts that were stamped, were stamped with the Chevrolet part number.

In 1948, Chevrolet asked Carter to redesign the W-1, adding a basic fast idle, which was really a hand throttle that was used in conjunction automatically with the choke. This feature appeared on the 684s for 1949 on both passenger and truck, and in 1950 on trucks with 216's only (no passenger).

In 1949, Rochester started building carburetor, beginning with the (opinion) horrible type AA, which thankfully lasted only 2 years.

I do not know the source of the order, but Chevrolet stopped buying Carter for passenger vehicles in 1950, and trucks (other than C.O.E. models) in 1951. Remember, Rochester was a G.M. company.

Chevrolet also added the Rochester type B as a factory service carb for 1937~1949 vehicles.

Naturally, Carter was less than thrilled about losing a customer particularly after redesigning the carburetor for the customer.

As Carter now had the YF carburetor, the CEO of Carter order direct bolt-on replacements to replace the Rochester B, and swore they would sell 1 million of these!

Rochester made a two-barrel version of the B (the BB), (opinion, also horrible) but fortunately, it lasted only a single year!

The Carter YF had a very successful run, being used from 1950 through 1985.

Jon

Here is Carter carburetor number 1:

Jon

No, I'm interested in driveability not originality.

Carbking,

A lot of the stuff Daytona got from Carter is in the form of microfiche cards - thousands of them. They also have regular paper stuff.

Carbking, speaking of Stromburg carbs, I have a 1939 Packard with a Carter carburetor. It was equipped with a Stromburg by the factory. In your opinion, which carb gives the best service?

We got over 12,000 aperature cards, but I got a lot of prints earlier. We didn't get any Carter microfiche. The aperature cards are 80 column IBM punch cards, with a piece of 35mm film inserted in the last 40 columns. The first 40 were punched like other data cards, and thus they could be sorted, or (slowly) accessed by card number.

I have not found ANY way to digitize these without spending a small fortune!

As to the Packard, the Stromberg is probably a "better quality" carb, but the Carter will outperform the Stromberg.

This particular Carter design tends to warp where the throttle body meets the bowl (the bowl can easily be straightened, and good for another 10 years). This design only lasted a few years, and when Carter changed designs, they totally fixed the issue.

Jon.

Cool, thanks. I'll keep the Carter. It's been rebuilt but the car was hardly ever driven before I bought it. It had stumbling issues but those have decreased with use. After spraying it with carb cleaner and putting over 500 miles on it it has improved dramatically. it's still not exactly right, though.

I'll be calling you Monday about the Carter YF kit.

Thanks a lot.

From your last number, I am GUESSING it is a "marriage" carburetor.

I don't have 6-1658 in my database, but in 1959 Carter was in the 6-1400's

Jon.