possible carburetor swap

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mopardude70

mopardude70

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San Fernando Valley, California
I've got a '70 Duster with its original 225 slant 6 and 1 barrel carb. Does anyone have any thoughts on either a 2 barrel carb or 4 barrel carb swap? I want to keep it all original since it gets great mpg, but it could use a bit more power and takes a while to get up to speed.
 
Let me start off by saying that I have sold performance parts for slant 6 engines, but I have never personally worked on one. your best bet is probably Clifford Performance, they have a 6=8 Mopar 225 combo that they claim increases power 70%. Who knows how true that 70% figure is, but it should certainly increase power. Comes with an aluminum intake, a 2 barrel Weber carb, and headers. It is here:
https://cliffordperformance.net/store/ols/products/68-mopar-225-coombination
With the Weber 2 barrel, I would expect gas mileage to be about the same, or maybe a bit less than it currently is, but it should certainly have more power.

Offenhauser makes some 4 barrel intakes too, and you can get a set of headers. The Holley 390 CFM vacuum secondary carb used to be very popular with the slant 6 crowd. I believe that the 390 has become extremely expensive lately, over $700...
 
I agree with the super 6 setup
I have converted a few and it does make a difference, and adjusted out right you also get better mileage.
 
The first thing to think of, is will California allow you to make any changes to your car?
 
I'm running the super 6 setup. Factory 2 barrel manifold with the BBD carb and choke deleted. Clifford long tube headers into true dual 2.5" exhaust. It's faster than the wife's Mazda CX5 and gets 20 mpg. Can't go wrong with the Super 6!
 
I might literally be the only person alive who runs a Super Six intake topped with a Carter WCD. Had bad luck with BBD's, and, just happened upon this garbage in a scrapyard still bolted to an old AMC 196. Somehow even though the car had been there so long it had mostly rotted away, the carb was cherry and the accelerator pump even still worked.

Long story short, if you can live without PCV, excellent carb. Also decent tuning parts interchangability with the AFB, which makes it infinately more tunable than the BBD.
 
Good luck finding a super-six 2 bbl intake today. Even luckier if the later aluminum ones. Might be easier to find a used 4 bbl Offenhauser or Clifford intake on ebay. Perhaps the only new choice is the Australian Hurricane, which has long runners and a high price (>$500) for the bling. A batch of 4 bbl Offy's showed up on a web site a few years ago (J.C. Whitney?) and were snapped up in a day via word of mouth here and Moparts. Don't know if a lost lot or a new production run. Might be neat to fit an EFI TBI to a 4 bbl intake. Some have integrated electronics and I think you can install smaller MPFI injectors to match the needs of a slant. Some are now <$1000.
 
Super-Six 2bbl package was never available in CA. So the supply here is limited, and expensive when you do find one.
 
cpreal said:
Super-Six 2bbl package was never available in CA. So the supply here is limited, and expensive when you do find one.
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The super six was a truck only here, with far less emissions tied to it. The only super six's I've seen here are on M/T trucks and I grabbed the intake and kickdown bracket off it but failed to get the candy cane.....
 
I would love to do one with a Weber progressive 2 barrel on one, one day, but the only problem is, there's only ONE. It's the measly 32/36 and it's too small for anything other than a stone stock 170. They can be tuned on and adjusted a LOT, but there's just no way they'll ever flow enough even for a stock 225. I put the Offenhauser 4 barrel intake with a QFT 450 vacuum secondary four barrel on mine and it runs fantastic and gets decent mileage. Just remember, unless you also upgrade the exhaust, you'll not see hardly any improvement. Putting more in the engine means you need to be able to get more out. I don't have a header on mine. I had the original exhaust manifold gasket matched and the outlet opened up to 2.5" and also put the TTI complete 2.5" exhaust on it. Man that really made a difference.
 
pishta said:
The super six was a truck only here, with far less emissions tied to it. The only super six's I've seen here are on M/T trucks and I grabbed the intake and kickdown bracket off it but failed to get the candy cane.....
Click to expand...
There's a guy selling repops in the for sale section.
 
pishta said:
The super six was a truck only here, with far less emissions tied to it. The only super six's I've seen here are on M/T trucks and I grabbed the intake and kickdown bracket off it but failed to get the candy cane.....
Click to expand...
A m/t anything won't have that candy cane part because there's no kickdown linkage needed with a m/t.
 
volaredon said:
A m/t anything won't have that candy cane part because there's no kickdown linkage needed with a m/t.
Click to expand...
O dhit... that's why I didn't get it...it didn't have it ! DOH! But I still think I got the correct bracket for it....looks the same..we're the M/T 2bbls the same throttle bracket, just didn't have the candy cane or lickdown rod?
 
Readjust your mechanical valves, that will be a big performance boost in itself.

1970 225 slant 6
Wonder if it has ever been done in the last 52 years, probably not.

1664914828389.jpeg
 
I just swapped a stock 1bbl to a super six setup. there was some futzing about with the kick down because not all of the linkage was there, but the Carter BBD 2bbl was cake to dial in.

client was smiling ear to ear after the test drive and said it was totally new beast after a weekend of cruising it up in the hills.

if you have any questions hit me up, I'm in SFV too.
 
Good info here gang. Thank you for sharing. So........ My apologies for hijacking this discussion, but I'm trying to figure out the best set up as well, for my 73 /6 225. I have a brand new Offy 4V aluminum intake and am unsure of the best carb to use on this setup. I understand the need for opening up the exhast to breather better, etc. Just not sure of which carb will be of best use for me. Daily driver, no racing involved on my end.
 
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