3 1bbl setup

[Inline6Merc]

These 2 weeks I have off, im building up my head. I plan to run 3 1bbl's. I have a question about the set up. When you stick them on the head and turn over the key, all the carbs would be running? correct? How do you make it so that, just the center carb is runing all the time and the other two only work when you step down of the gas pedal? How do your guys 3bbl set ups work? thanks for the help

Later,

Curtis

 

[Inline6Merc]

i just had an idea. What if you leaned out the two outside carbs. Just take the idel screw and turn it down so the carbs hardly pump gas in the engine until you step down on it. WOuld that work?

Later,

Curtis

 

[Anonymous]

It's done with throttle adjustment. The throttles are adjusted so that only the center carb is working at idle and lower RPM.

 

[Anonymous]

It's called a progressive linkage.

 

[Anonymous]

If all 3 carbs open at the same time, at low rpm's, you are likely to have a big bog in acceleration similar to putting to large of a 4 bbl on an engine.

 

[Inline6Merc]

progresive linkage wont help all 3 carbs open at the same time that just controls when the carbs open. The carbs still pump fuel into the engine at idle. What would hapen is what 66 Fastback 200 said. It would have a big bog in acceleration. I think by adjusting the idle on the outer carbs so they barely pump fuel into the engine it should be fine. Becaus when they fully open fuel will dump inn.

Later,

Curtis

 

[CobraSix]

When I ran it, I closed the idle air mix screw on the outers. It had a bog if you really stomped on the gas so you pretty much had to always ease into it relatively speaking.

Slade

 

[Anonymous]

The progressive linkage that comes with the Offy manifold allows you to adjust for when you want the outside carbs to kick in. Mine idles off of the center carb only as controled by the linkage. I am running the Webers right out of the box.

 

[Soldmy66]

From what I've read, all tri-power systems only run off of the center carb at idle and under low-throttle conditions. This is true even with aftermarket V8 systems, such as the Barry Grant 3X2. The intent of progressive linkage is to allow the outer carbs to begin opening at some pre-determined throttle setting. I would assume, but can't say with certainty, that the idle screw would be closed.

 

[JOHN G]

if you are using the weber carbs, one would disconnect the idle control solenoids on the first and third carbs-if you are using others(autolites?) back the idle screws all the way out so that the butterflys are shut tight until they are opened by the progressive linkage. springs installed on the first and third carbs to lightly hold them shut at idle-the vacuum can actually pull them open and create lean conditions. let me know what carbs you have as i have those springs lying around.

 

[CobraSix]

John brings up a good point. I had to use some heavy springs to make sure the outers closed all the way at idle and off throttle.

Slade

 

[Inline6Merc]

im running 3 autolites.

later,

Curtis

 

[hotrodbob]

3 duce set ups use carb bases at each end that do not have an idle circut. No idle adjustment screws on the outside carbs. Block off the idle flow on your 1 bbl and acchieve the same thing. You will also have to adjust the accelerator pump stroke on all the carbs to make sure you get enough fuel. You may also have to play with jet size as the three carbs are set to run as a single set up. I ran 3 carbs in high school, but do not remember a bog issue. I used carbs off a 144 on the outside and the 200 in the center.