The Ford Barn

Charles Reese · 09-26-2013, 02:55 PM

Can anyone direct me to concise (practical) information on the ‘care & feeding’ of the double venturi Holley/Zenith carburetor? In particular, adjusting for idle speed and most economical driving settings. Is there any real difference from the single venturi?

Patrick L. · 09-26-2013, 03:01 PM

As far as I know, there is no difference. External adjustments are the same from what I know. I've wanted to get one and give it a try, its been said they idle better and run smoother at low speeds. It probably doesn't perform as good at higher speeds,but, most of us aren't in any hurry. I'm not at least.

Tom Endy · 09-26-2013, 03:29 PM

Quote:

Originally Posted by Charles Reese

Can anyone direct me to concise (practical) information on the ‘care & feeding’ of the double venturi Holley/Zenith carburetor? In particular, adjusting for idle speed and most economical driving settings. Is there any real difference from the single venturi?

There is some difference. The double venture casting does not have a screw-in secondary well as the single's do. The well is part of the casting. There are also locating pins in the casting that orient the double venture.

Tom Endy

kenparker · 09-26-2013, 03:42 PM

Got one on my 28 pickup now. It has a very smooth and slow idle as in one can count the revolutions. Since it is not a good thing to run one that slow of an idle I have it set a little on the fast side now. The truck has not been out on the highway since rebuild/restoration. This Saturday will be it first out of town trip. We will see how the Double Venturi performs at above 25 mph.

al's28/33 · 09-26-2013, 04:36 PM

My double V also works extremely well since rebuild and now have over 600 miles on it.

Charles Reese · 09-26-2013, 05:41 PM

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Quote:

Originally Posted by kenparker

It has a very smooth and slow idle as in one can count the revolutions. Since it is not a good thing to run one that slow of an idle I have it set a little on the fast side now.

what i'm seeking is info on how to adjust to low idle .. at the moment it seems to idle faster than i would expect ...

Patrick L. · 09-26-2013, 06:01 PM

What are you doing to try and adjust it ? There is a idle mixture adjustment screw with a spring on it. Initial setting should be about 1.5 turns from seated. Once engine is warm just turn that screw to obtain smoothest idle. There is an idle speed adjustment screw near the throttle shaft, adjust that to the desired engine speed.

Charles Reese · 09-26-2013, 07:41 PM

THANKS everyone ... i was concerned about maybe having to so some adjusting to the size of the holes in the jets ... seems not the case .... adjustment on throttle lever has helped a lot!!

Fred · 09-27-2013, 11:34 AM

Quote:

Originally Posted by Charles Reese

THANKS everyone ... i was concerned about maybe having to so some adjusting to the size of the holes in the jets ... seems not the case .... adjustment on throttle lever has helped a lot!!

Chuck, Take it over to the Fair Grounds (RIR) and run a few fast laps & all will be OK !!

Rowdy · 09-27-2013, 11:37 AM

I am suprised you are having to adjust that carb if it is the one I sent you rebuilt by Ben Neiman. The other carbs I had him rebuild ran perfect right out of the box. Rod

09-26-2013, 02:55 PM	#1
Charles Reese Senior Member Join Date: May 2010 Location: Richmond, VA Posts: 882	Double Venturi Carburetor Can anyone direct me to concise (practical) information on the ‘care & feeding’ of the double venturi Holley/Zenith carburetor? In particular, adjusting for idle speed and most economical driving settings. Is there any real difference from the single venturi?

09-26-2013, 03:01 PM	#2
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Double Venturi Carburetor As far as I know, there is no difference. External adjustments are the same from what I know. I've wanted to get one and give it a try, its been said they idle better and run smoother at low speeds. It probably doesn't perform as good at higher speeds,but, most of us aren't in any hurry. I'm not at least.

09-26-2013, 03:42 PM	#4
kenparker Senior Member Join Date: May 2010 Location: Van, Texas Posts: 1,122	Re: Double Venturi Carburetor Got one on my 28 pickup now. It has a very smooth and slow idle as in one can count the revolutions. Since it is not a good thing to run one that slow of an idle I have it set a little on the fast side now. The truck has not been out on the highway since rebuild/restoration. This Saturday will be it first out of town trip. We will see how the Double Venturi performs at above 25 mph.

09-26-2013, 04:36 PM	#5
al's28/33 Senior Member Join Date: Jun 2010 Location: Redwood City, CA Posts: 1,591	Re: Double Venturi Carburetor My double V also works extremely well since rebuild and now have over 600 miles on it. __________________ 1928 "A" Phaeton (mid year with many early features) 1933 "V8" Closed-Cab Pickup Truck (originally a Model B, 4 Cylinder dating to May, 1933)

09-26-2013, 06:01 PM	#7
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Double Venturi Carburetor What are you doing to try and adjust it ? There is a idle mixture adjustment screw with a spring on it. Initial setting should be about 1.5 turns from seated. Once engine is warm just turn that screw to obtain smoothest idle. There is an idle speed adjustment screw near the throttle shaft, adjust that to the desired engine speed.

09-26-2013, 07:41 PM	#8
Charles Reese Senior Member Join Date: May 2010 Location: Richmond, VA Posts: 882	Re: Double Venturi Carburetor THANKS everyone ... i was concerned about maybe having to so some adjusting to the size of the holes in the jets ... seems not the case .... adjustment on throttle lever has helped a lot!!

09-27-2013, 11:37 AM	#10
Rowdy BANNED Join Date: May 2010 Location: Gothenburg Nebraska Just off I-80 Posts: 4,893	Re: Double Venturi Carburetor I am suprised you are having to adjust that carb if it is the one I sent you rebuilt by Ben Neiman. The other carbs I had him rebuild ran perfect right out of the box. Rod __________________ Do the RIGHT thing - Support the H.A.M.B. Alliance!!!!