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Super Six vs a small 4bbl
https://www.slantsix.org/forum/viewtopic.php?t=42071		 Page 1 of 3
Author:  Josh P [ Tue Sep 28, 2010 2:12 am ]
Post subject:  Super Six vs a small 4bbl
Having looked for a Super Six setup and coming up empty handed, I'm now considering a small 4bbl and need some advice...

If I go the 4bbl route, the plan is an Offy and a 4bbl with small primaries (possibly smaller than a BBD?), then work something out for the throttle and kickdown linkage.

So the first question, is this a bad idea and why?

What would be the recommended 4bbl?

Are there any options for quality aftermarket throttle and kickdown linkage?

What would the estimated price difference be between finding a complete Super Six setup or going with a 4bbl?

Does anybody have a Super Six or Offy they are looking to sell? :P


Goals are fuel economy and performance similar to a BBD.
Author:  Rick Covalt [ Tue Sep 28, 2010 3:37 am ]
Post subject:  Prices
If you keep your eyes open you can find an Offy for the prices some people are asking for the 2 barrel manifolds. I paid less than $100 for all 3 I have purchased. I would run a Edelbrock 500CFM. They generally run well right out of the box and have lots of tunability without dumping fuel everywhere like a Holley. One man's opinion.

Rick
Author:  Charrlie_S [ Tue Sep 28, 2010 3:43 am ]
Post subject: 
I have a complete used super six setup. I do need to look and see if the kickdown linkage is complete. The carb condition is unknown, and the air cleaner needs painting (as does everything). My personal opinion, is a super six at the going rate, plus what it costs to ship, is really not worth the price. I have not tried it myself, but I have thought a manifold like the "Offie" with a spread bore carb, like a "Q" jet, would work well on a slant. It would require some time be spent on tuning the carb/manifold to the engine.
Author:  maxracer [ Tue Sep 28, 2010 5:52 am ]
Post subject: 
charlie, are you talking about stock small cam? Do you think a 390 4bbl would work with a short runner intake?
best regards
MaX
Author:  2 Darts [ Tue Sep 28, 2010 7:32 am ]
Post subject:  Re: Super Six vs a small 4bbl
Quote:
If I go the 4bbl route, the plan is an Offy and a 4bbl with small primaries (possibly smaller than a BBD?), then work something out for the throttle and kickdown linkage.

So the first question, is this a bad idea and why?
Not a bad idea. If you curb the quest for power on the street, it may even get better fuel mileage.
Quote:
What would be the recommended 4bbl?
For the street, the 390 cfm Holley. If you're going racing try something in the 500 cfm range. Mopar has done some testing with the /6-Offy-390 combination and has recommendations in the Six Cylinder book as far as jetting and ignition set up.
Quote:
Are there any options for quality aftermarket throttle and kickdown linkage?
For a throttle linkage, get a cable linkage setup from a V-8 car. For kickdown linkage, some use Lokar. I am using a Bouchillon Performance cable on my car.

Sorry, I'm not up on going rates of hardware. There is plenty of stuff floating around.
Author:  maxracer [ Tue Sep 28, 2010 10:40 am ]
Post subject: 
thanks Josh...............It all costs......................LOL*
Author:  newpoppop [ Tue Sep 28, 2010 11:00 am ]
Post subject:  4bbl
I have a 390 and the offy intake on my 65 Coronet now... have the hyperpak and shorty headers waiting to go on... have to do some 1/4 mile runs to get a base, and see what difference is...
Author:  maxracer [ Tue Sep 28, 2010 2:25 pm ]
Post subject: 
Please keep me informed, remember. I only have a stock cam
Regards
MaX
Author:  Charrlie_S [ Tue Sep 28, 2010 7:41 pm ]
Post subject: 
Quote:
charlie, are you talking about stock small cam? Do you think a 390 4bbl would work with a short runner intake?
best regards
MaX
Personally, I would not spend the money on a manifold and 4bbl, for a stock engine, unless it is just for eye candy. My choice for a limited funds build on a basically sound engine, would be this.
1)Mill head for about 9.0-1 compression. While the head is off, if you want to take the time, do some minor pocket porting. (assuming the valves are in good condition)
2)mild cam
3) open up the exhaust system
4) electronic ign
5)Then, maybe some carburation.

MPGFanatic, has a 64 Valiant 170 3sp on the columm. The engine has 9.5-1 compression, the mild MP cam, stock exhaust manifold, with a free flowing system, stock intake with a 1920 1bbl carb. The car gets about 26-27 mpg, and if I remember correctly low 17's high 16's in the 1/4 mile. This with a rookie race driver, columm shifter, open rear, street tires. The engine was a total rebuild, and fresh, however.

A 390 vac sec carb does work with a short runner manifold. Many slanters run that. That is what I have on my 66 Valiant.
Author:  Josh P [ Tue Sep 28, 2010 9:25 pm ]
Post subject: 
Is there a way to convert the CFM ratings between 3" Hg and 1.5" Hg. I'm trying to figure out how much difference there would be between a Holley 390 and the Carter BBD (rated 280 CFM @ 3" Hg, right?).

Also, will the Offy+390 setup cause much hesitation with a stock motor? I'm planning a trip to the machinist with my head soon, but plan to run the new carb and manifold in the meantime (as long as its not a huge hit in drivability).
Author:  Reed [ Tue Sep 28, 2010 10:49 pm ]
Post subject: 
Listen to Charlie. He gives excellent, sage advice...
Author:  emsvitil [ Tue Sep 28, 2010 11:19 pm ]
Post subject: 
2bbl cfm = square-root(3" / 1.5") * 4bbl cfm

4bbl cfm = sqrt (1.5"/3") * 2bbl cfm
Author:  Josh P [ Wed Sep 29, 2010 12:29 am ]
Post subject: 
Quote:
2bbl cfm = square-root(3" / 1.5") * 4bbl cfm

4bbl cfm = sqrt (1.5"/3") * 2bbl cfm
Just curious, is it possible that these are backwards?

For example.
sqrt(3"/1.5")*280 = 395
sqrt(1.5"/3")*390 = 275

If the above is correct, that would mean the Holley 390 would be right on the money and possibly get better millage than a BBD.

Is the Holley 390 easy to tune, reliable, any tips?

Also, are there other intake options I should consider? I saw a thread (which I can't find at the moment) about the new AS Hurricane (the smaller one). Is it a 2bbl or a 4bbl intake, and is it heated?
Author:  olafla [ Wed Sep 29, 2010 3:34 am ]
Post subject: 
Hi Josh P, if you are set on finding yourself a new manifold anyway, you could go for an offy, and maybe get a low priced second hand 2bbl on an adapter plate to start with. If you have an automatic you could also go for a kickdown cable instead of the super six kickdown setup, then you can upgrade to a 4bbl later without starting all over again.

Olaf.
Author:  66aCUDA [ Wed Sep 29, 2010 6:38 am ]
Post subject: 
I know that the Aussie Speed Hurricane long runners are available in 2 bbl or 4 bbl with a heater box accessary. I havent had my hands on the short runner version yet but it was designed to have a heater box in it.
Frank Brent
Aussie Speed US Distributor
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