Anybody Running a Offenhauser 5186 - Offenhauser 360 Degree Dual Quad Low-Rise intake

[Mike Z]

I have this intake on my 400 with a strait linkage. Getting too much gas running to rich cause always both carbs are running equal.
Is it possible to run a progressive linkage.
I always see dual quad set ups running the rear carb as the primary. Is it possible to run the front carb as the primary?
Probobly going to go to a 4bbl but I think this would work out if I could run a progreesive linkage
What confuses me is that the split design would not feed sufficient fuel to all cylenders when cruising.
Thanks in advance.
Mike Z.

 

[67 B-body]

Just a thought,,,,
Can't you jet down the primary's to not run rich? The combination of air and fuel gives you a rich or lean condition,,,, not the number of throttle plates opening....
I don't think your linkage is causing you this trouble....

 

[Garys1969RR]

While the 2-4 barrel set up does look impressive, a good dual plane intake such as the RPM Performer would be a better all around choice. Also use a good 4 barrel like a Holley 600 or maybe a 750 CFM. Usually vacumn secondaries works best for street use. How extensive is your build? Cam, heads, porting, headers, etc. On a 400 you would really have to have a pretty radical build to need that much carburetion. I dont know how to get 2 AFB carbs to open 2 barrels at a time. Your always going to have 4 barrels opening at once, then another 4 when you step on it. Even the 440 6 pak ran on the center 2 barrels most of the time. Only thing I can think of is to Lean out your primaries for a start. Or go to a single 4 barrel.

 

[Mike Z]

Thanks Gary and 67 B Body. I'm going to go to a 4bbl with a performed rpm intake. This set up was on it when I bought it.
I love the look. But the motor is not enough to take it.
Thanks Again.
Mike Z.

 

[Meep-Meep]

If you go with a progressive linkage then use the rear carb as the primary. This I believe will provide better fuel distribution while running at light loads. I have the exact same intake for a 440 but haven't run it yet but I had one on my boat for a while (455 Olds) and it ran OK as a progressive setup. This is a divided plenum single plane design and I think there is a small balance passage between the two sides. What I would do is run two small carbs like the old 400 CFM AFB's (9400) and hook them up in a progressive fashion. Sure a modern perf RPM with a dialed in single carb can do very well, and even better, but that doesn't mean you can't make this setup work with tuning. Your immediate problem is like 67 B body said. What carbs are you running? 625's? Check the float level and put the jets and rods back to the basic setting (if they aren't already) then go from there. I will say if you have to drastically alter the jetting that is a sign you need different carbs. I would start with something smaller like even the 500's.

 

[lewtot184]

edelbrock progressive linkage.

 

[Meep-Meep]

edelbrock progressive linkage.

Daym that's purdy :love2:

 

[lewtot184]

Daym that's purdy :love2:

one of these days i'll get around to using it,...lol.

 

[lewtot184]

running straight linkage vs progressive shouldn't have any effect on a/f mix. could be several issues such as: is the ignition curve not compatable with the camshaft, are the metering rod pistons stuck or rods bent? what type of spark plugs? thats an out dated intake but no reason it can't be made to drive ok. those look like older aftermarket afb's. what series/cfm rating are they?

 

[RustyRatRod]

Maybe I missed it, but what size are the carbs? Square bore carbs tend to run richer than spread bores. So that needs to be kept in mind when tuning them. The primaries usually end up being way leaner than running one by itself, since there are two. My guess is that the carbs are running way rich on the primary side. Usually the case with dual carbs. If you decide to try and tune them before you remove the setup, keep that in mind.

 

[Mike Z]

Meep And Lew.
I Like the look but I'm going to just go to the Edelbrock Performer RPM and let the duals go.
They are AFB Competition Series 625 carburators.
Thanks Much for the thoughts and your time.
I'll have to cut the cables and housings to make the rear carb the primary so if I decide to change to a 4 bbl a bunch more cash for new cables.
Thats a Sweet Looking Set up Lew.
Mike Z.

 

[fiorock]

The Offy does make a pretty good blower manifold, though... :toothy5:

 

[lewtot184]

The Offy does make a pretty good blower manifold, though... :toothy5:

oh boy!:blob1:

 

[Meep-Meep]

Yep, I've seen people use the old iron intake without the extensive mods as seen here for the poser blower application. Needless to say the above pictured example is a much better approach! Well done!

 

[rumblefish360]

400 cube? A pair of 500's max, the 400's would be best.

 

[Mike Z]

Fiorock.
Thats a sweet looking set up.
Mike Z.

 

[Mike Z]

Thanks Guys,
The Offenhauser is going away soon to a new owner.
Last night I ordered my Edelbrock Performer RPM and a New Holley.
I'm knowing it will have better drivabiliy and probobly pick up some power too.
I need all I can get in Chevy country.
Nothing wrong with a little drag.
Mike Z.

 

[rumblefish360]

Nice. That Offy is NOT the Power set up you want to whoop it up with. It is a eye candy part.