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| BBD Jetting https://slantsix.org/forum/viewtopic.php?t=15034 |
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| Author: | Greg Ondayko [ Mon Nov 14, 2005 8:43 am ] |
| Post subject: | BBD Jetting |
I have a bone stock 79 BBD/ BBS Not sure which is the correct term / model - Anyway, it is off a 79 super six - I wanted to richen the jets up a bit - can I use the jets from an afb/ avs strip kit for this? - Sorry -- Do not want to to to a holley 390 or a 4 bbl. Greg |
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| Author: | SlantSixDan [ Mon Nov 14, 2005 11:08 am ] |
| Post subject: | |
No, the 4bbl jets don't fit the BBD . Why do you want it richer? |
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| Author: | Greg Ondayko [ Mon Nov 14, 2005 7:25 pm ] |
| Post subject: | |
Well, The original engine on my 79 volare started knocking at 165500 {Rod KNOCK}(probably From using Fram's all those years). it had never been apart - Original timing chain and all - Man was that thing wasted!! So I put in another motor - While it was all apart, I put in a .460 lift mopar (direct Connection Cam) SI OS / SS valves, double roller Chain and Milled the head .100" . Now it runs a little hotter, and pings a little more - Set the timing at Mechanical 30* at full rpm. Will try going to 89 octane - have to run out the 87 first. Just wanted to check into some options - that's all. - Maybe I try a 318 Carb too. Are the jets any bigger in a 318 carb - BBD? Greg |
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| Author: | SlantSixDan [ Mon Nov 14, 2005 7:32 pm ] |
| Post subject: | |
Well, those Carter jets...! I like Carter carbs, in general, but one thing I like better about Holleys is the simple, sequential-numbered jet system that fits all Holley carbs. Carters, on the other hand, geeze. A 120-263 is one size richer than a 120-268 and two sizes smaller than a 120-293...OMG, WTF! The 318 BBDs are a little larger in most respects (venturis, jets, throats...) |
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| Author: | sandy in BC [ Mon Nov 14, 2005 8:18 pm ] |
| Post subject: | |
Sounds like Greg and Sandy are on the same loop.... Runs too hot,,,cant take out enough advance,,,a little too lean Weld up the slots,,,drill out the jets |
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| Author: | Slant6Ram [ Tue Nov 15, 2005 7:10 pm ] |
| Post subject: | Deleted |
Deleted double post |
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| Author: | Slant6Ram [ Tue Nov 15, 2005 7:10 pm ] |
| Post subject: | Carter carbs |
Greg, I've look inside a couple of those carters and I can tell you this. The metering rods in the stock six version look like a long and narrow taper compared to the fat blunt taper on the 318 version. Looks like the 318 version would give you a lot more fuel at wide open throttle. I'm using a 318 model in my Aspen. I think you might still need better gas, because my Aspen has only a stock cam and doesn't really run best until the metering rods are set all the way up. So high in fact, on my last run at Indy, one of the rods pulled out of the jet and jammed sideways, sticking me at wide open throttle and forcing me to shut down to make the turn. I'm guessing that you've already raised the metering rods as high as you could in the carb you've got. I guess I'm not surprised that it can't keep up with the large cam. In regard to timing adjustment: If you are getting ping at mid throttle, you might be getting too much vacuum advance. The vacuum can rate should be adjustable but the total amount of advance from the can is not adjustable. You might want to downgrade from the stock vacuum can (if it's an 11, because that's 22* at the crank) An 8 or 9 can should be available from any parts store. Also, a little heavier light spring on the mechanical advance might improve things. |
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| Author: | rrither [ Wed Nov 16, 2005 8:03 am ] |
| Post subject: | Carter strip kit |
I have been using the jets from a kit for a AFB. They do fit, and I see no differences under close inspection. Now, I am no expert on carburation, but I have been using this kit successfully on a BBD for about 10 years now on a daily driver. I have switched jet sizes as modifications occur, and just to experiment. I keep carful records of jet sizes, rod numbers (sizes), and the effects. I have found 4 different rod sets from junk yards, to throw into the mix. Yes, the carter numbering system seems to have no relation to the actual size, very confusing. I have found the stock rods, with one step richer jetting to be the best for my engine. Ross. |
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| Author: | Greg Ondayko [ Wed Nov 16, 2005 8:49 am ] |
| Post subject: | |
Thanks Guys, Some conflicting info from Ross and Dennis on the jets- I did not have the time to experiment, bit it looked like a swap could be made. All seem to agree that the carter Numbering system sucks here - I am with dennis - The carters are good carbs - but they should have put some more forethought into the numbers. I filled up with a tank of better gas. We'll see. Paul - I actually do not want to play with the rod height - as it is my driver and I do not intend to race it. (although it is an easy adjustment ) I might break out the strip kit and try some jets out. Greg Greg |
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| Author: | SlantSixDan [ Wed Nov 16, 2005 9:19 am ] |
| Post subject: | |
Just occurred to me where the conflicting jet info is coming from: Early vs. late BBDs. I'm not sure exactly when the changeover was, think it was in '76 but might've been one or two years earlier than that. The early-type carbs (without mechanical linkage to the step-up rods) use tall jets similar to those found in a BBS. The later-type carbs (with the raised top casting and mechanical linkage to the step-up rods) use totally different jets and step up rods. |
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| Author: | Greg Ondayko [ Tue Nov 22, 2005 8:18 am ] |
| Post subject: | |
Was experimenting with the carb last night and my strip kit jets do fit in my BBS - Stock jets are .086" - I tried both the .092" and the.089" jets with no improvement. - Now I cant get the car to idle - I had it at least idling with ths stock jets. - I now have reinstalled the stock .086 jets, but the idle is non existent. I believe I might have messed up those ilde screws at the bottom of the carb. I have the slow idle screw turned all the way in and it will not idle - just stalls. Help. Greg |
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| Author: | Greg Ondayko [ Fri Nov 25, 2005 1:54 pm ] |
| Post subject: | |
Got it working Finally! The problem was this: First I had upgraded to a .460" lift cam with 268* Duration. The slant six carb was not supplying enough air / fuel at idle. The venturi on the original super six carb is 1 1/16". I found a carb off of a 318 that had the venturi size of 1 3/16". So that worked, and I swapped all of the 318 metering rods / Jets too. FYI the Factory serviece manual was a crucial part for me is solving this problem. Good thing i have about 10 years worth of them from 69 - 79. There is much valuable info in there, as D/W has noted before. I would reccommend that you get one for your year car. Greg |
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| Author: | Greg Ondayko [ Sun Dec 04, 2005 10:42 am ] |
| Post subject: | |
Follow up On this jetting / Metering rod / Venturi Issue. Well I had the 318 venturi and all related parts in the car. It ran fine, but got ok gas mileage, and had real stinky exhaust. I left the .089" jets in but swapped back to the original slant 6 metering rods. this combo worked real good. I also tried putting the .086" Jets from the slat six carb with the slant six rods. The result was way too lean.. the car was starved for fuel. Last thing I tried was keeping the .086" Jets, but swapping the 318 rods back in. They are a little smaller and let a bit more fuel by. It idles a bit smoother with this setup and hopefully i will get some better MPG. Greg |
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| Author: | Greg Ondayko [ Tue Jan 03, 2006 4:01 am ] |
| Post subject: | |
Follow up Here on My jetting I am Using basically a 318 BBD - .089" Jets and 318 Metering rods, with a larger venturi From a 318. Once I got the correct Spark Plug heat range, and correct Timing advance curve worked out, I got 17 MPG Highway with a 3.23 and 904 auto/ p195 - 75 - 14's I thought that was respectable for the heavy f- body. Greg |
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| Author: | Greg Ondayko [ Thu Mar 23, 2006 8:52 am ] |
| Post subject: | |
After my torque converter disaster See here http://www.slantsix.org/forum/viewtopic.php?t=16505 I decided to go to a stick for my 79 F body Duster. I Want an 833 OD But haven't found one yet; So I have a complete 79 Aspen 3speed parts machine. I swapped the floor hump, and Pedals and Column, and Trans and Bell housing. I am now getting 19.8 MPG city with the 3 speed and 3.23's with 195 tires. Greg |
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