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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old March 7th, 2014, 04:11 AM
jonneess jonneess is offline
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Cool 66 305E with 2g rochester carburetor

I have a 66 suburban with a V6 305E. It had an old 2g Rochester carb on it. From all my research I learned this is not the original carb that came on it. I'm rebuilding the carb but I cant find the float height and float drop given that its going on my V6. My carb doesn't have its number tag on it and its an early enough model that it doesn't have the number stamped on the side which clearly hasn't helped in my search for carb settings. Any help would be appreciated.
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Old March 7th, 2014, 04:53 AM
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Default Re: 66 305E with 2g rochester card

Welcome to the forum, Jon!

I'm sure most of us would recommend ditching that Rochester and going with a new Holley.

See http://6066gmcclub.com/gmcguy/holley.html
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Old March 7th, 2014, 10:23 PM
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Default Re: 66 305E with 2g rochester carburetor

Welcome Jonneess!

I echo what Ed has already stated, but here a few links with maybe some info about 2G's; if and when you decide to go the Holley route.

http://oldcarmanualproject.com/manua...ual/index.html

http://www.carburetor-blog.com/roche...gc-carburetor/
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Old March 8th, 2014, 02:20 PM
tommyduncan tommyduncan is offline
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Default Re: 66 305E with 2g rochester carburetor

I gave one of those a try on an odd fire v6 I used to have. I never found a quality rebuild kit for them. I was constantly battling with the accelerator pump coming apart. Others really liked those carbs though. Couldn't hurt to try.

I think the rebuild kit comes with a little measuring device for setting the float. I would set it there and adjust it afterwards anyways. The accelerator pump is filled from the float bowl by a low spot in the wall between them. If the float level isn't high enough you will have a dead spot right off idle. Some people grind the low spot lower if nothing else helps.

The kits I got came with many different gaskets that I didn't need. If you don't have any numbers to go by you might have to guess and hope it has what you need. I don't believe they came with jets or anything so you will probably be OK.
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Old March 8th, 2014, 07:13 PM
jonneess jonneess is offline
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Default Re: 66 305E with 2g rochester carburetor

I looked into the Holley but decided I wanted to keep it as old school as possible since everything else is stock on it. Should I just set the float for a generic 283 or 307? I have the rebuild kit and have it almost all put back together but without my carb number I don't know if the float needs to be at a special level or at the generic engine settings. The specs that came with my rebuild kit are no help without my carb number. My other option is buying a new Stromberg WW for 200. Any opinions about the Stromberg since it should have been my original carb.
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Old March 8th, 2014, 09:20 PM
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Default Re: 66 305E with 2g rochester carburetor

My suggestion, and im not a pro at anything but breathing and sometimes I mess that up, but I suggest getting a used ww for $25-$50.00, rebuild it with a $14.00 kit, and go to town! I love my WW and since I got it tuned in right and the timing set you can't kill it. Very simple and foolproof in my experience, and I'm an idiot so it has to be easy to work on or I'll break it.

For the float I figured out that they like to be seated well with the float just below level, at least that was what mine was at. So you can use a small level or your Iphone and cline-o-meter ap and make sure it's seated, then bend it to just a degree or so below "level". It should be just about right on at that point.



Here's a stromberg ww on Evilbay at $40.00 http://www.ebay.com/itm/STROMBERG-WW...70abdb&vxp=mtr
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Last edited by FetchMeAPepsi; March 8th, 2014 at 09:25 PM.
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Old March 9th, 2014, 07:10 AM
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Default Re: 66 305E with 2g rochester carburetor

Run the Rochester. Set the carb up for a mid 60's Chevy. Don't be fooled by the Holley 500. Compared to a worn out stromberg the Holley seems great but apples to apples the Holley is crap. The best mileage I have got is with a new ww stromberg. The Rochester should be like the ww in performance on the v6. I run the old Rochester carbs on Chevys and really they are easy to deal with. This group thinks the Holley will give better mileage and drivability but after running 20 or more v6 gmc trucks with every thing including gm tbi the Holley has proven to have the worst mpg. The ww stromberg in new condition has given me an average of 14 mpg in a 3/4 ton truck with 3.54 gears and man trans and 15 in a half ton with 3.07. The best is a tbi in a 1/2 ton with man trans and 3.07 at about16 mpg. The Holley 500 has never given better than 12 mpg. Period... Same truck with the tbi. 66 half ton with 3.07 rear. The Holley really does no good until about 3,500 rpm. Since I really won't run a 305 v6 past 3500 I don't see the reason. Finally I have run the Holley or it's motocraft counterpart on a number of amc v8 rigs and can say I like it on a 304 but that engine runs all day past 3500. Barry
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Old March 9th, 2014, 07:23 AM
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Default Re: 66 305E with 2g rochester carburetor

A little follow up. Every day I run a gmc v6 from 25 below to 100 above. Ww stromberg and point ignitition. 10 seconds to start. My summer rigs include a v6 gmc with a 1904 Holley and point ignition. Same with it. Pull the choke pump the gas and start. Bang in a few seconds.
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Old September 12th, 2020, 01:00 PM
RedElvis RedElvis is offline
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Default Re: 66 305E with 2g rochester carburetor

Reviving this thread with a question.. Does the 2G Rochester bolt right on to the 305 V6 manifold with no conversion plate? Looks like the bolt spread is the same for the small bore 2G.. Working on a friend's 305 that has the Stromberg and it's leaking.. Linkage is also quite sloppy..
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Old September 19th, 2020, 03:20 PM
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Default Re: 66 305E with 2g rochester carburetor

Redelvis:
I needed a conversion plate to run 2g on my 305. Although bolt pattern was the same, gasket surface was bigger on 2g than the manifold.

Hope that helps.
Regards
Steve
New Orleans
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