I am currently building a turbo slant six engine and bought a offenhauser dual carb intake manifold that also came with two holley 1920 carbs. Does anyone have any recomendations for carburetor choices? I dont want to waste time with the holley 1920 carbs if there is a better choice to start with. steve

Welcome to the site!

IMHO, it would be much easier to run a single carb with a blow-through turbo setup. Several people have used Carter BBDs on a Supersix intake. Not sure if anyone has run boost through a 1920...

Happy building,

Lou

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Home of Slant6-powered fun machines since 1988

I saw a blow through slant 6 with the original 1920 on the web once. Oh, here it is: http://www.angelfire.com/rant/jaymossite/schwoch1.html

Anyhow his 16.88 second ET is almost exactly what my normally aspirated '67 Valiant does in the 1/4 mile. My car has the stock short block, stock cam, a ported big valve head, Offy 4bbl intake and 2 1/4" exhaust. Oh, head, 3-speed column shift and 3.21 gears.

I've been considering a blow through turbo 225 a good long time. I would use a small double pump Holley or a 500 Edelbrock carb on a 4bbl intake feed it with EFI fuel pump and control it with a bypass type pressure regulator.

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Joshua

I got a blowthrough barry grant mighty demon carb for my setup. It would be much easier using one carb also in my opinion.

Kev

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Excellent advice here. But it would be cool to run twins w/ a dual carb setup...would have to run an equalizing tube between each turbo. What a nightmare this would be to tune! Later

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I havnt thought about using the 1920,s in a blow through, but I have seen duels run good with a turbo. The thing to do is build a hat that covers both carbs together, this will even out the boost between them.


IMHO unless your a seasoned tuner on blow through systems I would go another route on this. A good quick, cheap and dependable setup to learn on and still make big power would be to use a Two barrel factory intake, or maybe one of the aftermarket 4 barrel intakes with a Holey 500 two barrel on it. They are easy to mod for blow through, plus cheap to get even if you have ot buy new. PLus the Holley four barrel turbo hats that are around for blow through will fit right on the 500 two barrel so you dont have to make a hat.


I will have to admite a turbo on a set of 1920,s would be cool. But I think it would take a lot to get them to work good. With a 500 two barrel you could make 300 to 450hp if the turbo system was a good one. If you used the Offy four barrel intake you could upgrade latter to four barrel without changing anything if you had enought turbo to even make use of that much carb. Plus with the Holley 500 two barrel you only have to mod two barrels, one float/bowl setup so it would be easy to do, and tune.


Once you learn whats up on tuning then you could go crazy without much hassle. Swap a four barrel on and bigger turbo and have at it. The main think is going to be have a good fuel system to feed the carb ( fuel pump, regulator setup that works with turbo) and if you biuld it right , here again the same setup that works with the 500 two barrel would work with a four barrel latter.

The little 1920 might be able to work but getting good needle valve and seat, boost referancing the power valve system on it, and even getting floats that can take it might be hard to pull off(plus some other fun stuff). Not impossible, but with so much info out there on the Holley big carbs a 500 two barrel would be a breeze and cheap. Heck even the 350 two barrel Holley would work and its the same platform and parts needed.

If you was to use a Holley four barrel you need a machanical secondary carb ( no vacume seconday,s, they want work in a blow through) and that can get into money. Plus thats two of everything needed, twice the money, twice the chance for problems).

I have thought about using two Webber 32/36's on that intake with blow through. But that would not be easy, or cheap. And a whole lot of work.

If you did run Duel carbs of any kind you had better be able to check the fuel on each cylinder with a wide band O2, or atleast each bank/set of three cylinders that go with each carb.


Jess

So are we saying that the holley 2300 is the easiest? and if so, what one 350 or 500 CFM?

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Either one, I would probably use ever which one I found the cheapest. There is a lot of info out there about how to mod the Holley 4 barrel for this, and the 350/500 are nothing but half of one of these carbs. Be sure and get one with the center hung floats though because it will need the extra fuel storage in the float to feed it.


Do a Google search for Hanger18 Holley Blow-thu carb mods, its a good artical that shows how to change these carbs to blow-thu yourself. The 500 2 barrel Holley is half a 750 so all the info dirrectly fits, except only half the work and parts. Those carbs work great on the slant in a N/A setup, after mods it will do the same in a blow-thu setup.


Jess

I've read the hanger 18 mod page almost enough to have it memorized. What took me a while to understand was why one would do all of that stuff. I had to know not just what to do, but why as well. I had to supplement that article with some others that explain in further detail individual topics.
For example, what are the vent tubes for? and why are there different mods for the power valve ( BRPV vs leaving it stock and drilling out the restirctors, or changing the reference point )

As for the 350CFM
vs the 500CFM
... looks like the 500 is cheaper

According to Holley's carb documentation the 500CFM comes with a 73 main jet, .028 pump nozzle and a 50 power valve ( 5.0" vac )
and the 350CFM comes with a 61 main jet, .031 pump nozzle and an 80 power valve.
Additionally I've been told that the 350CFM has a 30cc accelerator pump shot and 1 1/2" bores and the 500CFM has a 50cc pump shot and 1 11/16 bores.
All of that in mind, I still don't know what one to pick...

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My '73 "Gold" Duster /6
http://www.cardomain.com/ride/2789359

I run a 2300 350 CFM N/A on my Dart, and it is a beautiful thing. Had to change jets and shooter, but that's it.

Want to sell you dual Carb manifold? I've been looking for one for years. We could trade manifolds and carbs... my intake is awesome, built custom by Josh Skinner and it works great with my Carb which is basically what you are looking for.

Let me know!

~RDE~[/i]

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1984 D100 Shorty Custom
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What number jet and shooter did you end up using?

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My '73 "Gold" Duster /6
http://www.cardomain.com/ride/2789359

#60 jet, 25 shooter.

_________________
1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing