You need to have an electron microscope to read the numbers on the jets
Did you dissasmble the hex head screw on the metering rod tree when you were rebuilding it?
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| BBD running too rich - jetting or metering rods??? https://slantsix.org/forum/viewtopic.php?t=36499 |
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| Author: | Fab64 [ Tue Jul 28, 2009 11:55 am ] |
| Post subject: | BBD running too rich - jetting or metering rods??? |
Hi all, I've been combing thru old posts, but haven't yet found what I'm looking for. I need some help with my Carter BBD carburetor. I have a 225 cu. in., recently-rebuilt to stock specs, with automatic trans, in a '67 Barracuda. I installed a Super Six setup that is supposedly from a '77-80 Aspen/Volare. The car runs well but is getting very poor mileage (~ 11-12 mpg) and seems to be running extremely rich (exhaust smells strong, lots of black soot around tailpipe). I've tried adjusting the metering rods, to lean it out a bit, but didn't notice any difference. Now I'm wondering about the Main Metering Jets. How much do these jets and the metering rods affect the mixture when the engine is off idle? I'm wondering if a prior owner may have put larger jets in it? Does anyone know what the standard jet size is for a BBD from a 225? I suppose it's possible this carb could have come off a 318 - would a 318 require larger jets? I'd appreciate any help or suggestions on what could be causing this, thanks. Roger |
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| Author: | Wizard [ Tue Jul 28, 2009 3:03 pm ] |
| Post subject: | |
Ignition not quite right, clogged idle air jet, or too fat idle jet? Checked that choke is opened all the way open after few minutes? Even main jet too big if you are into venturi too much? Cheers, Wizard |
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| Author: | Rug_Trucker [ Tue Jul 28, 2009 4:01 pm ] |
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AFAIK the jets are the same. The rods are definately different! Check float height. The 318 rods shouldn't give you a black tail pipe. |
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| Author: | pmarvetz [ Tue Jul 28, 2009 10:24 pm ] |
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The two carbs I have here have 120-388 jets. |
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| Author: | Fab64 [ Tue Jul 28, 2009 11:11 pm ] |
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Thanks everybody for the replies so far. I re-built the carb before putting it on the engine, so nothing should be clogged or gummed up. I also double-checked my float height a while back, and it was set correctly. The choke appears to be functioning properly, pull-off works, etc. I'll look to see what size jets I have tomorrow. Roger |
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| Author: | Rug_Trucker [ Wed Jul 29, 2009 5:28 am ] |
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You need to have an electron microscope to read the numbers on the jets Did you dissasmble the hex head screw on the metering rod tree when you were rebuilding it? |
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| Author: | Fab64 [ Wed Jul 29, 2009 8:24 am ] |
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Quote: You need to have an electron microscope to read the numbers on the jets
No, I didn't completely disassemble it. I pulled it out as a unit, but I removed and cleaned the rods themselves. Should I have taken the whole thing apart? Did you dissasmble the hex head screw on the metering rod tree when you were rebuilding it? The BBD manual (link provided by Dan) seems to imply that the rods are primarily responsible for metering fuel during regular driving (more so than the main metering jets). Is this correct? I'm going to try backing the adjusting screw out a bit more and see what happens. I've tried this once, but maybe I didn't go far enough. |
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| Author: | Rug_Trucker [ Wed Jul 29, 2009 10:40 am ] |
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If that screw is not been tampered with? I would leave it alone. Anything above a proper idle is controlled by the jets and rods. One way to check and see if you have a super six carb is the PCV fitting. If it is bent, SS! Also above the idle screws they are more restrictive on the SS. 2 little square or rectangular holes. Also the top of the carb is different. I forget the details, it's on the video. Something to do where the stud for the air cleaner is. The rod adjustment is on that little cam that lifts the rods. Just a thought......if you spin the fuel inlet when attaching the line it will change the float setting! Of course it would lower it if it tightened in the bowl. When I rebuild them I spray the WD40 through everything to make sure they are clear. Removing the jets can be tricky. Some I have left in because the screw driver mauls the slot. I have removed them on AFB's with a propane torch. Heat and cool cycles and shoot penetrating oil in them. |
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| Author: | Rug_Trucker [ Wed Jul 29, 2009 10:43 am ] |
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I think I had a bunch of info on the sticky above and it got deleted or edited. I used a micrometer on the rods. |
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| Author: | RustyRamcharger [ Wed Jul 29, 2009 5:46 pm ] |
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Quote: Removing the jets can be tricky. Some I have left in because the screw driver mauls the slot. I have removed them on AFB's with a propane torch. Heat and cool cycles and shoot penetrating oil in them.
Using the correct screwdriver prevents damage. You need to use a hollow ground screwdriver with a blade as wide or slightly wider than the jets. This type screwdriver is used in gunsmithing. It is easily recognized by the surfaces of the blade tip being ground parallel. A standard screwdriver has tapered sided, which act as ramps to cam the screwdriver out of the screw slot.Ken 
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| Author: | Rug_Trucker [ Wed Jul 29, 2009 7:37 pm ] |
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Well I learned something new today RR! I guess Ace hardware won't have them on the shelf will they? The area where the jets are is tight for a tapered one. On top of that dissimilar metals screwed together. 
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