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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old October 11th, 2021, 06:23 PM
CMCamp CMCamp is online now
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Default Rochester Dualjet Carb

Hi All, I'm a newbie to the forum. This is my first post. My experience has been restoring old Mercedes, so my recent purchase of a 1962 GMC K1001 Panel truck takes me a little outside my comfort zone. Here's my question. The truck has a 305 V6 with a WW Stromberg carb. I have seen recommendations in several forums to upgrade to a Holley 2bbl carb to improve performance. However, I have access to a brand new Rochester Dualjet carb for free. Does anyone have experience putting this carb on the 305? If so, did you experience any performance improvement?
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Old October 11th, 2021, 06:48 PM
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Default Re: Rochester Dualjet Carb

Welcome to the forum CMCamp!

I do not have any experience with that carb but I have seen another truck with a Quadrajet mounted up to a 351E.

I would love to see some photos of your Panel!
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Old October 14th, 2021, 03:42 AM
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Default Re: Rochester Dualjet Carb

Like everything else on that motor, the WW was part of a design package. It is a 2bbl. Very fine carb. Rebuild it and use it. Anything else is opening up an unnecessary bag of worms. The motor can't use any more than 285 CFM. It's not made to spin up more than 3800 RPM. You can't chase speed of truck with carbs. You chase it with gear ratios. A carb handles good starting, good idling, good acceleration and brings motor up to cruise RPM. That's it.

If a person causes a motor to go beyond max RPM, they have breathed too much starting fluid and are crazy in the head.

You can't use performance in the traditional sense with a GMC 305 V6. It was built to torque and have extreme reliability.

Last edited by AZKen; October 14th, 2021 at 04:42 AM.
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Old October 14th, 2021, 07:13 AM
BobBray BobBray is offline
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Default Re: Rochester Dualjet Carb

Interestingly enough, a few late production 1969 GMC pickups with 305 V-6's were factory equipped with Rochester 2G's. However, a 2G and a Dual-Jet are 2 different carburetors. The Dual-Jet is basically the front half of a Quadra-Jet with no secondary's and came out in the 70's as an emissions-tuned carb. for Buick V-6's and other small GM V-8's. Some of the early ones actually bolt to a 4bbl. Quadra-Jet intake manifold. I wouldn't run one, I think you will have problems bolting it to the 305's intake manifold and it's likely calibrated way too lean for a 305 anyway. The WW is a great carburetor and is just the right size for a 305 as AZKen pointed out. The 351 and larger V-6's are a different story, they run very well with the 500 cfm Holley 2300.

Last edited by BobBray; October 14th, 2021 at 07:22 AM.
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Old October 14th, 2021, 02:10 PM
George Bongert George Bongert is offline
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Default Re: Rochester Dualjet Carb

Quote:
Originally Posted by AZKen View Post
Like everything else on that motor, the WW was part of a design package. It is a 2bbl. Very fine carb. Rebuild it and use it. Anything else is opening up an unnecessary bag of worms. The motor can't use any more than 285 CFM. It's not made to spin up more than 3800 RPM. You can't chase speed of truck with carbs. You chase it with gear ratios. A carb handles good starting, good idling, good acceleration and brings motor up to cruise RPM. That's it.

If a person causes a motor to go beyond max RPM, they have breathed too much starting fluid and are crazy in the head.

You can't use performance in the traditional sense with a GMC 305 V6. It was built to torque and have extreme reliability.

I agree, AZKen.The only way I would put a Rochester 2BBL Carb on one of these engines is if the Carter WW is a total loss and not able to be rebuilt. Outside of that, your last statement very succinctly put would be that these Big Block V6's were built to be WORKHORSES, not RACEHORSES!

Last edited by George Bongert; October 14th, 2021 at 02:13 PM. Reason: Punctuation correction
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Old October 14th, 2021, 03:36 PM
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Default Re: Rochester Dualjet Carb

Wow! This is exactly the kind of feedback I was looking for. Thanks. It’s a rebuild of the existing carb that will go into the work plan.
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