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| Super six conversion rejetting issues https://slantsix.org/forum/viewtopic.php?t=7440 |
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| Author: | bossanova6 [ Tue Nov 04, 2003 10:15 pm ] |
| Post subject: | Super six conversion rejetting issues |
Hi All, I'm about to embark on the super six conversion.I got the two barral carb off a 318.I was talking to a guy at the carburetor shop who said I would have to rejet the carb because it was designed for 318ci not 225 ci (ie would run to rich)According to the super six conversion article that is available on this site,it's supposed to be a straight bolt on.Can anyone clarify this issue? |
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| Author: | 69a100 [ Wed Nov 05, 2003 9:23 am ] |
| Post subject: | Crabs |
I learned something a few days ago, There are 2 types of BBDs, if you got yours off a 318 and you look at the bottom of the carb, there are 2 holes in the throttle plates. The slant carb doesn't. Theres a article in the archives that explains this. |
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| Author: | 70valiant [ Wed Nov 05, 2003 10:55 am ] |
| Post subject: | |
I have 4 BBD's 2from slants and 2 from V8's 3 have the hole in the choke plate none have holes in the throttle plates. I think there were literally a dozen slight variations but all are BBD's, All you can do is try it out and see how it works. V8 BBD's have larger venturies and jets thus more power, supposedly about a 5% increase in power over a /6 BBD. I felt this power when I changed from the /6 to V8 carb. |
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| Author: | kesteb [ Wed Nov 05, 2003 1:09 pm ] |
| Post subject: | |
The only major difference between the 318 BBD and the \6 BBD is the size of the venturi. The 318 has larger venturi, thus flows more air. The jets and rods are the same. |
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| Author: | XECUTE [ Fri Nov 07, 2003 4:26 am ] |
| Post subject: | |
The rule with carb jetting is that generally if your engine can produce as much peak power as the car its transplanted from, it will work. Jet sizing is based around how many cc/minute booth jets can flow. Quote 1: Quote: Ken Duckworth, a Cosworth enginer, found an engine needs a minimum of 3.2 cc/min per hp produced. A fuel injected 500 hp Cosworth DFV needs 1640 cc/minute.
On an in-liner, fuel distribution isn't so good. If an engine produces 150 hp, then it needs about 750-900 cc/minute, or 5 to 6 times the target hp in fuel flow (cc/min). Some Holley and Barry Grant Holley carb jet charts rate cc per minute of gas flow. Quote 2: Quote: I've found that on an inline six and V8, you just take the target flywheel hp, and select a set of jets that discharge 5 to 6 times the hp level in cc/min. The tables specify jet sizes that produce a flow rate. Use 6 if you want it rich for power, 5 times if you want it lean for the street.
Here are the Holley 2-bbl jet sizes. Hope these can help with the Carter carb jets.Red indicates the best estimate figures. HolleyWeber and Holley 2300/4150/4160/4165/41754180/4500 jets are not the same, and I've not seen all the data for all jets 40 to 59. Smaller jets have more headloss, and flow much worse than there area would suggest. Those from 60 to 100 are form the Barry Grant © 1997, catalogue 123 cc/min or 40 thou nominal, 40 call size jet 129 cc/min or 41 thou nominal, 41 call size jet 136 cc/min or 42 thou nominal, 42 call size jet 142 cc/min or 43 thou nominal, 43 call size jet 149 cc/min or 44 thou nominal, 44 call size jet 157 cc/min or 45 thou nominal, 45 call size jet 164 cc/min or 45 thou nominal, 46 call size jet 171 cc/min or 47 thou nominal, 47 call size jet 178 cc/min or 48 thou nominal, 48 call size jet 185 cc/min or 48 thou nominal, 49 call size jet 192 cc/min or 49 thou nominal, 50 call size jet 198 cc/min or 50 thou nominal, 51 call size jet 205 cc/min or 52 thou nominal, 52 call size jet 212 cc/min or 52 thou nominal, 53 call size jet 221 cc/min or 53 thou nominal, 54 call size jet 230 cc/min or 54 thou nominal, 55 call size jet 239 cc/min or 55 thou nominal, 56 call size jet 248 cc/min or 56 thou nominal, 57 call size jet 257 cc/min or 57 thou nominal, 58 call size jet 267 cc/min or 58 thou nominal, 59 call size jet 285 cc/min or 60 thou nominal, 60 call size jet 298 cc/min or 60 thou nominal, 61 call size jet 311 cc/min or 61 thou nominal, 62 call size jet 325 cc/min or 62 thou nominal, 63 call size jet 341 cc/min or 64 thou nominal, 64 call size jet 357 cc/min or 65 thou nominal, 65 call size jet 374 cc/min or 66 thou nominal, 66 call size jet 392 cc/min or 68 thou nominal, 67 call size jet 411 cc/min or 69 thou nominal, 68 call size jet 429 cc/min or 70 thou nominal, 69 call size jet 448 cc/min or 73 thou nominal, 70 call size jet 470 cc/min or 76 thou nominal, 71 call size jet 492 cc/min or 79 thou nominal, 72 call size jet 517 cc/min or 79 thou nominal, 73 call size jet 542 cc/min or 81 thou nominal, 74 call size jet 566 cc/min or 82 thou nominal, 75 call size jet 587 cc/min or 84 thou nominal, 76 call size jet 615 cc/min or 86 thou nominal, 77 call size jet 645 cc/min or 89 thou nominal, 78 call size jet 677 cc/min or 91 thou nominal, 79 call size jet 703 cc/min or 93 thou nominal, 80 call size jet 731 cc/min or 93 thou nominal, 81 call size jet 765 cc/min or 93 thou nominal, 82 call size jet 795 cc/min or 94 thou nominal, 83 call size jet 824 cc/min or 99 thou nominal, 84 call size jet 858 cc/min or 100 thou nominal, 85 call size jet 890 cc/min or 101 thou nominal, 86 call size jet 923 cc/min or 103 thou nominal, 87 call size jet 952 cc/min or 104 thou nominal, 88 call size jet 987 cc/min or 104 thou nominal, 89 call size jet 1014 cc/min or 104 thou nominal, 90 call size jet 1080 cc/min or 105 thou nominal, 91 call size jet 1150 cc/min or 105 thou nominal, 92 call size jet 1200 cc/min or 105 thou nominal, 93 call size jet 1260 cc/min or 108 thou nominal, 94 call size jet 1320 cc/min or 118 thou nominal, 95 call size jet 1375 cc/min or 118 thou nominal, 96 call size jet 1440 cc/min or 125 thou nominal, 97 call size jet 1500 cc/min or 125 thou nominal, 98 call size jet 1570 cc/min or 125 thou nominal, 99 call size jet 1640 cc/min or 128 thou nominal, 100 call size jet Venturi area is a factor in peak power as well. In Australia, 265 Hemi in line sixes got the very same carb as the 318 LA 2-BBL. The six was faster, easier on gas, and yet was rated 10 hp or so lower. A larger venturi improves top end power, with a slight loss in low speed tractorbility. But again, a 225 slant, especially, has bag loads of torque from idle to half revs, so a V8 carb isn't going to be a miss-match at all. There are enough good header set ups, good ignition and intake manifolds around to boost a 225 slant to a net rating of 150 hp with a larger venturi 2-bbl carb. The metering rods are another issue, but as long as it idles and doesn't lean out, then it'll drink from that bigger leaker like a party animal. The bigger slant has good effective compression and a huge piston speed which makes the carb think its right at home. Hope this helped a little. |
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| Author: | 70valiant [ Fri Nov 07, 2003 4:31 am ] |
| Post subject: | |
so you are saying no need to to rejet EXCUTE? |
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| Author: | XECUTE [ Sat Nov 08, 2003 12:02 am ] |
| Post subject: | |
Yup. Go do it! You'll not be disappointed. |
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| Author: | 63gtcv [ Sat Nov 08, 2003 8:08 am ] |
| Post subject: | Bbd |
I did this a few years ago on my 63 dart, along with Dutra duals. I pulled the carb off a 318 truck. Being a 63 head without hardened seats, 'a little rich' is not bad. To me, looking at the plugs, the engine, with over 200,000 mi., is well able to process this much fuel. For sure you will like the difference. |
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| Author: | 83Ram150dude [ Sat Nov 08, 2003 2:10 pm ] |
| Post subject: | |
OK Here's my 2 cents, When I first got my Ram it had a Holley 2280 2bbl of off a 318 on it......ran like dog......old dog......jetted WAY too lean for the six. So lean that it would ping on any octane gas, and had no throttle response to the point of a massive bog after 3/4 throttle, falling flat on its face. I was almost ready to replace the ESC Lean Burn computer because everyone told me that was what my problem was. Well, took a trip to the local junk yard, looking for an old style electronic distributor actually, but found an almost new Carter BBD on a truck in the yard same year as mine. Fifteen bucks lighter in the wallet and it was mine, just couldn't pass that one up. Never did find that distributor though. Anyway, took it home cleaned it up bolted it on, and guess what? No more pings, all kinds of power, no more bogs, and even runs on 87 octane now. My advice is to keep the BBD you have, maybe the 318 BBD is jetted differently than the Holley 2280 was, maybe it was a real late lean burn carb, I'm not sure, all I do know is that the Holley that was supposed to be an "improvement" over the Carter sure wasn't in this case......watch out, not all 318 carbs are the same! |
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| Author: | DusterIdiot [ Sat Nov 08, 2003 2:25 pm ] |
| Post subject: | Holley vs. carter |
Actually for late carbs the Holley 2280 wasn't an improvement over the BBD fuel delivery wise, it was an improvement 'emissions quality' wise....(i.e. 'lean' for improved smog-ability). -D.Idiot |
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