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2 barrel on a Dual Port Offy intake

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Crocodile
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Posts: 13
Joined: Sun Dec 27, 2015 10:40 pm

2 barrel on a Dual Port Offy intake

Post #1 by Crocodile » Wed Dec 30, 2015 11:25 pm

I was fortunate enough to hear about a used 4 barrel intake from a buddy, and went down to get it today. It turned out to be a DP. I would have ordered a "C" series if I was buying new, but feel fortunate to have found one at all!
I know that in proper use with a 4 barrel carb, the primaries run through the smaller portion of the intake runner, and the secondaries flow into the larger part when you "flush the toilet". Overall, I like the design, and actually have 3 of these intakes (for small blocks) hanging on my shop wall, as well as one on my 64 Falcon with a V8.
That said, I still would like to run an Autolite 2 barrel from a 302 on my 300 six, so I experimented a little with a junk carb I had sitting around. I could make a plate to place the 2 barrel over the intake openings for either the primary side, or the secondary side. Two of the carb mounting holes line up perfectly, but the carb has to face opposite directions for each choice of mounting. Here is an example pic, using a 2 barrel factory spacer I had:
Image
This is the orientation I think would perform best, as it is dumping into the larger, or "secondary" runners. I would need to move the throttle mounting ball to the bottom of the carburetor linkage to get the proper direction of travel, and the fuel line would be sort of clumsy, but otherwise it seems pretty straightforward. Here is how it would sit:
Image
My main question is, will using the runners for the secondaries alone flow enough to make this a worthwhile project? Or will it be too restricted? I can't imagine that it wouldn't outflow the stock "log" manifold, but I have been wrong before.
I could also just use an open plenum spacer and build a plate to center the 2 barrel above the intake, but I am worried that it would be a turbulent mess, and not run well at all.
I am looking forward to the input and experience you guys can share with me!

Fordman75
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Posts: 997
Joined: Fri Nov 08, 2002 2:43 am
Location: Southern, Minnesota

Re: 2 barrel on a Dual Port Offy intake

Post #2 by Fordman75 » Thu Dec 31, 2015 2:20 am

If it was me and I wanted to run a 2V carb I would sell the Dp and buy a C-series. Or post a ad and offer to trade the Dp for a C-series.

But if you are set on running the dp intake. I would run a 2" open carb spacer and make up an adapter plate to center the carb over it.
Ted

54 Ford F100/F150 4x4
300, NP435 4spd, NP205 transfercase

Sick6Turbo
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Joined: Sat Dec 19, 2015 12:53 pm
Location: Almond, Wi.

Re: 2 barrel on a Dual Port Offy intake

Post #3 by Sick6Turbo » Thu Dec 31, 2015 9:35 am

A friend ran an open spacer with a 350 holley 2v and the dp, ran good and didn't have any intake heat issues in the summer. I Turbo'd it and it still worked good.

If isolating 2 of the barrels, I would think using the 2 closest to the head would yield a warmer floor for fuel in cold weather.
Dale
79 F-100 turbocharged 300 rear mount 20 psi
Stock EFI bottom end, mild port carb head
12.44@106 1/4 mile in 2015

Crocodile
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Joined: Sun Dec 27, 2015 10:40 pm

Re: 2 barrel on a Dual Port Offy intake

Post #4 by Crocodile » Sat Jan 02, 2016 12:52 am

Even though money is a little tight this time of year, I decided that since I would eventually be going to a 4 barrel anyway, I might as well do it now. Just won this on eBay- hope it will be just what I need- http://www.ebay.com/itm/281894198662

Sick6Turbo
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Location: Almond, Wi.

Re: 2 barrel on a Dual Port Offy intake

Post #5 by Sick6Turbo » Sat Jan 02, 2016 9:23 am

:thumbup: Best of both worlds with the dp!

It looks like restrictor rings have been installed to in increase booster signal on the primary and secondaries to reduce cfm. Should really help the secondaries pull fuel, as it has been as issue with the 600/625 in mild and stock builds 400 cubic inch and down that I have done. I actually removed the secondary jets in one build, it helped but still need more secondary fuel. I also played with the flapper valve weights.

I really like the Eddy/Carter idle circuit, and have used washers and different springs to bring in the metering rod fuel faster on the primaries. It made my 400 crisp, it idled and drove like efi. Also a brand x 383 stroker went from being a dog to melting the tires from idle. Have fun!
Dale
79 F-100 turbocharged 300 rear mount 20 psi
Stock EFI bottom end, mild port carb head
12.44@106 1/4 mile in 2015

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worken2much
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Joined: Sat Jan 31, 2004 9:01 pm

Re: 2 barrel on a Dual Port Offy intake

Post #6 by worken2much » Sat Jan 02, 2016 11:58 am

I put a 4412 Holley 500 cfm two barrel on the dual port in my 33 Ford coupe. I positioned it with one barrel in the primary side and one in the secondary side. I made an adapter plate from 1/4" steel plate. That in turn sits atop a modified four hole aluminum spacer. There is a heavy gasket between the steel & aluminum adapters closing off the back two holes.

The club I race with most often dictates the two barrel otherwise I would run a four. I bought the intake early on before I had learned very much about the various intakes that are available. So, I just made it work. Have turned 6,000 a few times so it must flow ok. I would trade it for a C series if anyone is interested?

Good luck,
Worken2much
Rule #1. Six Cylinder Racers Have Longer Cranks.
Rule #2. Unless your given name is Richard...don't be a dick.

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MechRick
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Location: Las Vegas, NV

Re: 2 barrel on a Dual Port Offy intake

Post #7 by MechRick » Mon Jan 04, 2016 4:24 pm

I ran this setup on my '81 truck for a while. The two barrel was over the secondary section of the intake. Ran ok, although the rest of the engine was stock...

Eventually sprang for a Carter 500 cfm though.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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