Put together a 69 Dart w/ Clifford Headers, 3.55 Sure Grip, Reverse Manual Valve Body, 4 bl. Intake an an old AFB which I rebuilt orig. from a 65 Imperial. The car runs pretty good but when I step on it WOT it bogs.
I'm wondering if this is because it does not have a mechanical secondary valve (not missing- different design which doesn't incorporate it).
I have a later 9410 AFB 400 CFM which has the valve which I was thinking of switching and trying.
Any thoughts ???

That's probably your problem. Plus, those carbs flow around 550 cfm. The no secondary enrichment works OK on a big cube mill like a 413 with lots of pump shot, but bog city on your little slant six. If I had a 400 cfm carb (and I do! ), I'd definitely run it.

D/W

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If it ain't broke, fix it!

Thanks Dennis- sounds like no way I can make that carb work right with that limitation.
I'll try my 400 AFB- was reluctant to originally because it was kind of a nasty old core before I freshened it up and I was never able to get all
of the 4 jets out due to heavy corrosion.

Been there, done that. Mag wheel acid (the phosphoric acid stuff for uncoated wheels) helps on the heavily corroded ones. Your main concern is gonna be flakes of oxidation in the passages, so treat them, rinse and blow with compressed air repeatedly. I don't bother trying to get the jets out if it feels like the screwdriver's just gonna twist them off, I'd rather have them stuck than buggered up. I have had parts carbs where I used heat and penetrating oil for hours and even then had to practically melt the damn carb out from around the jets! They're just not worth it. Oh, yeah, the acid will leave a black phosphate residue which you may not like. You have to scrub with aluminum or steel wool and/or metal polish to get that off (or be creative). Of course, you can alwez shoot the outside with a good gas resistant silver engine paint...

D/W

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If it ain't broke, fix it!

Thanks again Dennis!
Any chance you would want to part with your 400 AFB
which is probably in much better shape than mine?
Forgot to say that the reason I wanted to be able to remove
the jets is to have the option to use others, as this is going
to be a street and bracket racer.
Wanted to be able to use other jets w/o having to drill
mine (w/ chips)

Ah yes. That's an oddball carb on several fronts. Its a small 4-barrel made to run on a BIG engine, in a BIG car, providing a lot of low-end torque and adequate high-speed power. It also has a smaller-than-normal air horn (same size as the large 2-bbl used on 383 engines) so finding an air cleaner that works will be interesting. There's no secondary air damper because its intended to be on an engine almost twice the displacement of a slant-6, which can handle the sudden opening of all 4 barrels. It does have mechanical secondaries, but the issue is that it has no air damper to bring them on-line slowly. I wouldn't think you could ever tune it to run well on a small engine. I'd go with the 9410.

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Yes, I'll gladly sell it to you for $3,500 and you get a whole 15 sec Duster with it.

D/W

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If it ain't broke, fix it!

Actually, the air horn is the same as all early AFB's, 4.875" Correction: on second thought, I think it's 4.625", but you get the idea..., I believe.

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If it ain't broke, fix it!

Were these carbs used on 273 Commandos too? I had one on my 318 (used the original Commando air cleaner and crinkle covers too), but the bog wouldn't go away even though it ran sweet otherwise.

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O==\=/==O

"A mechanic is Somebody."
- Jim Preston

That makes good sense. You can do a lot with just the metering rods on the primaries, though, and you'll probably have to solder and re-drill the secondary jets anyhow, since the sizes you need are pretty much made from unobtainium.

D/W

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If it ain't broke, fix it!

I've only seen the non-air door AFB's on big cars. All the 273 AFB's I've seen have the air door. You can adjust by adding or removing weight (a pain). A lot of the bog can come from primary metering that is slightly too lean, or not quite enough pump shot or duration especially.

D/W

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If it ain't broke, fix it!

Hey Dennis-
How about you list the Duster on Ebag "Buy It Now"
for $4000, perfect running car minus only the carb.
Then send said carb to me.
I get a free carb, you get an extra $500.
Hey the joys on being a tycoon!
Seriously though, thanks for all the advice.
Looks like I'll never be happy w/ the oddball carb
and if I spray it, it even sounds dangerous.

Do a search (like eBag) for the following original AFB's for a 273:

4119S
4120S
4121S
4122S
4294S
4295S
4304S
4305S

These should all be the 400 cfm variety that cam on Dart and Valiant 273 V8's in '66 and '67, although I haven't seen them all. The one in bold is the one installed on my Duster. The one you have is a 9000 series Carter aftermarket AFB, which is likely harder to find than an OEM one.

D/W

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If it ain't broke, fix it!

Thanks Dennis-
after digging out my 9410 AFB, I found the metering rods
and springs are missing.
Can you or anyone tell me what size rods were in that
carb, or in the equivalent 4294S carb you have on your car?
Also, do you know the orig. sizes of the primary jets?

.086 mains if memory serves correctly. I can't remember on the rods, I have it written down somewhere, I think they're .065 or .067 on the small end. I think I have the secondaries in the .055 - .065 range (staggered).

I think the .086 jets were extant in the carb from the 273 application, I believe it came with .083 secondary jets for the V8.

D/W

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If it ain't broke, fix it!