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2bbl Carter BBD from 318 to 225, can/should I make work?
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Author:  77vanner [ Mon Sep 03, 2007 3:30 pm ]
Post subject:  2bbl Carter BBD from 318 to 225, can/should I make work?
Equipment: 77 shorty van, 225, 2bbl Carter BBD, no emissions equipment (intake has EGR boltholes/plate, but port hole was welded/filled so no EGR in USE)

My 2bbl Carter BBD has severely worn throttle shaft (needs re-bushed) and mangled Idle mixture needles.
My brother picked me up a carb.
VERY nicely re-built BBD, but apparantly for a '60-73 273/318/361
When trying to install new carb, I get too high an idle (has the bypass holes in the butterfly).

I can rev up, slowly & smoothly, but when opening throttle valve quickly, it literally sounds like a balloon deflating (phhhbllhhbbllt) and stalls. Suspect vacuum signal (larger venturi on new carb)

QUESTIONS:
Can I get this carb to work adequately/optimally for this engine?
Can/should I try to mate the new throttle body to the old carb?
Thanks :)
Author:  Rug_Trucker [ Mon Sep 03, 2007 4:32 pm ]
Post subject: 
It could have a worn shaft too.
Author:  SlantSixDan [ Mon Sep 03, 2007 4:33 pm ]
Post subject: 
Where did your brother find this carb? There is no single BBD that adequately covers "1960-1973 273/318/361" applications...whose information are you quoting? It's tough to imagine exactly what this rebuilt carb you've got is, given that description, but it's probably an earlier air-bleed type BBD, while the '77 unit is a solid-fuel type. I can't remember offhand, but I think there'd be "dealbreaker" problems swapping the throttle bodies...vacuum passages not lining up, etc.

Those throttle plate holes are going to stymie your efforts. A good first step will be to try closing them off using small (very small!) screws and nuts, sealed with Loctite. Once you do that, you may be able to attain acceptable idle speed without uncovering the vacuum advance port. If not, you'd need to re-drill the throttle plates...starting small and working up in size until you get it dialled in. Buy a bunch of carb base gaskets! :twisted:

I don't think your stuttering on throttle snap-open is related to venturi size, simply because properly-built 273/318 carburetors have been made to run well on 225s. I've done so myself without too much difficulty. The problem you're getting may be a fair bit simpler than venturi sizing, in fact: The slant-6 choke pushrod doesn't hook properly to the V8 carb's choke lever. If you can get it to hook up at all, it'll tend to bind. If the choke's not closing, you'll have gasping and stuttering on rapid throttle opening until the engine's good and hot.

Of course, it's also possible that this "very nice" carburetor looks good, but contains problems (accelerator pump not working as it should or not assembled properly, step-up rods sticking down or not adjusted correctly, clogged internal passages).
Author:  Rug_Trucker [ Mon Sep 03, 2007 4:37 pm ]
Post subject: 
I didn't think these rods were adjustable.
:?:
The newer ones are. The ones that run the huge rods and tin covers over the accelerator pump/fuel bowl.
Author:  SlantSixDan [ Mon Sep 03, 2007 4:41 pm ]
Post subject: 
Quote:
I didn't think these rods were adjustable.
We don't yet know exactly what this "60-73" carb is.
Author:  Rug_Trucker [ Mon Sep 03, 2007 6:22 pm ]
Post subject: 
I know rods and jets swap between those years.
Author:  77vanner [ Tue Sep 04, 2007 3:56 am ]
Post subject: 
The carb is a Carter BBD 1-1/4
Mfd by Carter Carburetor, St Louis USA
#s on the castings as follows:
0-2060 (on bowl side) with a . after
I3 (or 13)
2122 (cast near choke shaft)
2125 (near intake manifold bolt hole)
2 (other side of choke shaft)
F16 (inside, opposite venturis)
11 (venturi cover)
ECS fuel bowl vent tube
The re-build sheet that came back with it (for adjustments) was numbered 50-498-1, printed in '76

It lists applications for '60-'68-273, '64-'73-318, '70-'73-362

Throttle shafts have been re-bushed with bronze bushings
Choke works fine. Had to adjust linkage a bit. Closes fully when cold, full open when warm.
The carb that was on the van has the tin cover, no ECS vent, with the pump lever on the side.
Hopefully these pictures will attach:(actual images, not stock photo)

Image[/img]
Author:  Rug_Trucker [ Tue Sep 04, 2007 11:36 am ]
Post subject: 
that's the small BBD. The nipple sticking out the passenger side is for the distributor.

Bigger 1 1/2" BBD's were probably for the 383's back in the 60's. I've never seen one of those big ones.
Author:  SlantSixDan [ Tue Sep 04, 2007 12:37 pm ]
Post subject: 
Unfortunately, none of the numbers you describe tells us what the carb was originally for. Carter identified their carburetors with a triangular aluminum tag secured under one of the bowl screws. Too many rebuilders (and all so-called "remanufacturers") toss out the tags. You're correct this is a 1¼" BBD, but there is no such thing as "the small BBD". There were many different 1¼" BBDs...not only differing in features and configurations, but also in venturi size, throttle bore, etc.

Looking at your pictures, this is an air-bleed BBD probably off a 1971-72 318. It may or may not be assembled with the proper gaskets (the throttle body-to-main-casting gasket looks a little suspicious, depending on whether that hole we see in the gasket just above and to the left of the throttle shaft does or doesn't create a vacuum leak). The throttle shaft has been rebushed with unusually thick-wall bushings...hope they got the throttle shaft back in the correct location. The surface finish is also of some concern; the carb has been abrasive-blasted and not properly recoated, so it will be very prone to corrosion (inside and out) particularly if your local gasoline contains alcohol.

The choke lever is, as I suspected, not correct for a slant-6 engine. You may be able to make it close OK and open OK, but in between there are likely to be problems that can cause the sort of driveability issues you originally described. You can remove the screw holding the choke lever onto the choke shaft, and swap the lever from your original slant-6 carb onto this one, then "adjust" (unbend) the choke linkage back the way it is supposed to be.

Previous comments regarding throttle plate holes, accelerator pump, step-up rods and general carburetor condition still apply. Previous questions regarding the source of this carb (where'd your brother find it, and who rebuilt it?) haven't yet been answered.
Quote:
It lists applications for '60-'68-273, '64-'73-318, '70-'73-362
Nope. (Again, whose information is this?) This carburetor could easily be made to fit and work correctly on '66-'72 273s and '66-'72 318s. With a swap to a '66-up air cleaner (which is not a realistic thing to expect John Q. Dontcare car owner to do when replacing his carb...even the consolidation-happy "remanufacturers" don't ask this) it could be made to fit and work correctly on a '60-'65 273 or 318. It is not applicable for any '73 engine (no venturi vacuum tap for EGR).

I think if I were you I would probably consider using this carburetor as a temporary "get by" unit while your original '77 unit is being refurbished.
Author:  Rug_Trucker [ Tue Sep 04, 2007 4:57 pm ]
Post subject: 
There was BBD's on 383's. I am sure they were the 1 1/2' BBD's.
Author:  SlantSixDan [ Tue Sep 04, 2007 4:58 pm ]
Post subject: 
Quote:
There was BBD's on 383's. I am sure they were the 1 1/2' BBD's.
Quite true on both counts, but what has that to do with this BBD, which is not for a 383? :?:
Author:  Rug_Trucker [ Tue Sep 04, 2007 10:36 pm ]
Post subject: 
Quite true on both counts, but what has that to do with this BBD, which is not for a 383? :?:[/quote]

Nodda damn thing! Just wish I had one :lol:
Author:  zedpapa [ Wed Sep 05, 2007 6:56 am ]
Post subject: 
Rug_Trucker you have mail.

zedpapa
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