Setting up dual quads.

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Crazy4408pac

N. Michigan
Joined
Jan 3, 2010
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Traverse City Michigan
Was at my local auto parts store, having coffee with the owner. A guy comes in, to get some oil, for his rig. Jeff (the owner) introduces us. The guy (Paul) asked me if I was the owner of the nasty Mopar, running around? He mentioned that he has a 58 Impala with a dual quad 348, 4 speed.

I asked if it would be possible the see it and I followed him to his place. Very nice plain Jane blue and white rig. Sounded really healthy. He followed me to my place, to check mine out. While talking with him, he asked how I had my carbs set-up. Note: We both have Edelbrock intakes and the same carbs.

Here's where it got interesting. He mentioned that a lot of factory dual quads, did not come with idle circuits, in the front carbs. You start by backing all the way out, on both of the throttle linkage idle screws. Then turn them each, 1/2 half turn,at a time, until it will start and stay running. You then adjust each the same amount of turns, until you reach your target idle rpm. Next you seat the front idle adjustment needles, close the front throttle and make all vacuum hook ups, to the back carb. PCV, brake booster, etc. No progressive linkage. Then you hook a vacuum gauge, to the back carb and set the idle mixture and you are done.

He says he has used this method on 4 different rigs. 3 Chevy. 1 Ford. The Impala has been running this way for 5 years.

After he left, I sat in the garage and thought about it and it actually made sense.

What's every ones thoughts, on this?
Thanks
 
I will be watching to see what responses you get.
I have a Eddy D66 manifold that I've been thinking
of messing with after the rest of the car is finished.
 
Even the --6 setups had idle circuits in the outer carbs, it's simply that you could not adjust them. I believe the same is true of the dual 4's

I see no reason why you could not "rough in" the idle on all 4's then lean out the front a bit and do final adjust on the rear

Remember.........the rear primaries are the closest thing to the "center of the engine" the 2 barrel if you will
 
Even the --6 setups had idle circuits in the outer carbs, it's simply that you could not adjust them. I believe the same is true of the dual 4's

I see no reason why you could not "rough in" the idle on all 4's then lean out the front a bit and do final adjust on the rear

Remember.........the rear primaries are the closest thing to the "center of the engine" the 2 barrel if you will

You could, but it won't run optimally. The idle circuit is also partially a transition circuit.
When using progressive linkage, the engine is pulling real fuel from the primary carbs boosters by the time the secondary side begins to open.
You don't have that situation when running 1 to 1 linkage. If your front carbs idle circuit is completely closed off, it will run lean at very small throttle opening
 
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