Rochester 2g

Greasy Chevy · Sep 13, 2011

ive searched but all i can find is information that ***umes i have an idea of what im talking about..
i want a chevy tripower setup. i understand the rochester 2gc is the carb to use?
now my question i have a 65 283 with a rochester 2 barrel carb is that automaticly a 2g(x) or is the 2g somthing specific? basicly is the 2g just any two barrel rochester with the last digit being the type choke? if not what makes a 2g and how can i tell?

jdj9410 · Sep 13, 2011

Here ya go all the 2G info should need http://www.oldcarmanualproject.com/manuals/Carbs/Rochester/2-Jet/Manual/index.html

David Chandler · Sep 13, 2011

Although I don't know the exact handle that they put on them, yours should be the correct carb. The ones on 305's, 350's and 400's were bigger, and have a slightly different bolt pattern (wider). My cousin had a tri power on a 265 back in the 60's and he used the small ones. I think cfm wise the small ones are around 250 plus or minus cfm. The larger ones are closer to 500 cfm, depending on who you wish to believe on the subject. Also the fuel line comes in from the front, on the larger ones, so they are harder to put close together. The early ones comes in from the side as far as I know. I have one and that is how that one was built and I believe that one came off of a 307.
Hope this helps.

ClayMart · Sep 13, 2011

Technically you only want choke provisions on the center carb. The end carbs don't need a choke, and for that matter they don't need idle circuits either. But if I understand correctly the 2G's (less chokes) can be modified to eliminate the idle circuits, idle speed adjustments and to ensure that the throttle blades close fully at idle.

Toner283 · Sep 13, 2011

Also keep in mind that you need to find three early carbs with the side inlet for the fuel line. the later ones were front inlet and when used in three two's format, they are too close together for the fuel lines to be attached. even with 90º fittings, there is no room between the carbs for the fuel lines.

JaxChevy · Sep 13, 2011

Yeah..what he said... The center carb has the choke and idle circuit. The end carbs have no choke or idle circuit - and the actual throttle plates are thicker on the end carbs - because they have to seal the throttle bore so there isn't a leak (it would lean our your mixture...) There are special bases available after market to help in the conversion. The end carbs have linkage to act as dumpers - basically to open after a certain throttle position. Check out www.vintagespeed.com for more info....

The factory 3x2 were almost always side feed - except for at least 1958 - they were on the front p***enger side corner - that's what mine are..and there is just enough room for the 90 degree fitting.

HTH,

Greasy Chevy · Sep 13, 2011

that was another question. ill have to check the carb i have and ill ***ume it has an automatic choke on it..so im looking for two 2g(manual choke) carbs. and take it from there?? does any one know can you convert a automatic choke to a manual/no choke? and toner can you define early? pre 70s?

thanks guys.

Toner283 · Sep 13, 2011

I have mine on an edelbrock manifold, they are close together and if it had front feed carbs the fuel line connection would be another 3/4 inch closer to the carb in front. Maybe early SBC 3X2 manifolds had wider carb spacing. I have looked at 348 manifolds & they seem to have more room between the carbs too.

Here's a pic of mine. not running yet, still collecting parts.

Greasy, pre 70's for sure, I am not sure exactly when they switched. I usually keep my eyes open at swap meets & such & buy them for 5 or 10 bucks. usually takes a few to get a good set of rebuildable cores.

Greasy Chevy · Sep 13, 2011

damn thats hot. are those all manual chokes? most of the ones ive been finding have a vacuum choke. did you remove the vacuum choke?

yekoms · Sep 13, 2011

http://www.hotrodcarbs.com/index.php

ClayMart · Sep 13, 2011

I think I may be confusing the issue here. Carbs with NO choke are going to be a lot harder to find than carbs with a choke. Did the 2GC model mean they had an integral choke (thermostat attached to the carb)? Was there a model 2GV that used a divorced choke (thermostat attached to the intake manifold)? Is that the model that can be converted to use as end carbs?

Somebody straighten me out before I make matters worse instead of better!

Greasy Chevy · Sep 13, 2011

heres what im thinking, the 2gv you can remove the choke?

<TABLE cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR vAlign=center align=left><TD vAlign=top width="48%" colSpan=4 align=left>The Model 2G carburetor is equipped with a manually-operated choke valve. Its major applications are on truck and marine engines where an automatic choke is not an absolute necessity.
</LEFT>

</TD><TD vAlign=top width="4%" align=left></TD><TD vAlign=top rowSpan=2 width="48%" colSpan=5 align=left><LEFT>
</LEFT>

</TD></TR><TR vAlign=center align=left><TD vAlign=top rowSpan=2 width="48%" colSpan=4 align=left><LEFT>The Model 2GC carburetor is the basic model 2G unit except the "C" designates an automatic choke which is an integral part of the carburetor unit. The automatic choke housing with thermostatic coil may be located on the air horn or throttle body, depending upon the application.
</LEFT>

</TD><TD vAlign=top width="4%" align=left></TD></TR><TR vAlign=center align=left><TD vAlign=top width="4%" align=left></TD><TD vAlign=top rowSpan=2 width="48%" colSpan=5 align=left><LEFT>
</LEFT>

</TD></TR><TR vAlign=center align=left><TD vAlign=top width="48%" colSpan=4 align=left><LEFT>The Model 2GV carburetor is also an automatic choke model; however, a vacuum break diaphragm unit(s) is used in place of the conventional choke housing and choke "

http://www.oldcarmanualproject.com/manuals/Carbs/Rochester/2-Jet/Manual/MCarbRoch1973__2G_0003.htm

</TD></TR></TBODY></TABLE>

yekoms · Sep 13, 2011

Yep, The choke can be removed. The site that I posted earlier has the stuff to plug the choke shaft holes.
Look at the trip conversion kits and it may help you get a better understanding of 2Gs.
There are a bunch of little differences in the 2Gs. It takes awhile to grasp them.

Smokey

Greasy Chevy · Sep 13, 2011

damn those kits are expensive. speedway has one too but it aint cheap. thanks again for the help guys. I wish i was more familiar with carbs, im thinking i might just try to find a cheap 2g on epay just so i can hold it in my hand and see what all theese places are talking about... and take it apart.

spark · Sep 13, 2011

I removed the choke on the 2 outside carbs (secondaries).

I pulled the top half of the carb and used a hacksaw blade to cut the br*** screw ends off level with the shaft.- The br*** screws are longer because when the carb is ***embled the ends of the screws are shanked (deformed) to prevent the screw from backing out and falling into the carb.

Once you cut of the protruding part of the screw, they will undo. Slide the choke blade out and remove the leavers at the end of the shaft and it will slide out.

I taped the shaft holes in the carb body and used a 2 ****on head stainless screws to seal the holes.

.

Greasy Chevy · Sep 13, 2011

oh yeah, does it matter what the carb was originally on? do they have to be chevy carbs?

spark · Sep 13, 2011

I hunted around and found ones that had the same leavers and bases (all off small cube chevs I think) over here 283, 305, 327 were the most common ones.

Mine are early ones with no numbers stamped on the fuel bowels and are small base.

carbking · Sep 13, 2011

I am sure you will have additional questions, but attempting to answer only the one you asked:

Many companies seem to begin their models or series using the letters of the alphabet; Rochester Carburetor was not an exception.

The first production design Rochester carburetor was the type A. That series was superceded by the type B, which was superceded by the type G, which was superceded by the type M.

Thus the "G" in the 2G is the design or type of carburetor.

The "2" represents the number of venturii (more commonly referred to as the number of barrels). There is also a 4G series (4 venturii), but no 1G series.

The letter following the 2G would represent the choke type, or lack thereof.

No suffix would mean either no choke or manual choke.
The suffix "C" would indicate an integral choke.
The suffic "V" would indicate a remote or divorced choke.

Thus a 2G could be either no choke (ie tripower end carb) or manual choke (often used on trucks).

A 2GC would indicate a carburetor with an integral choke.

A 2GV would indicate a carburetor with a remote or divorced choke.

Jon.

Toner283 · Sep 13, 2011

Greasy Chevy said: ↑

damn those kits are expensive. speedway has one too but it aint cheap. thanks again for the help guys. I wish i was more familiar with carbs, im thinking i might just try to find a cheap 2g on epay just so i can hold it in my hand and see what all theese places are talking about... and take it apart.
Click to expand...

If you think about it, they ones in the link smokey posted are very reasonably priced. You are getting all of the parts for properly rebuilding three carburetors, including 3 new non leaking small baseplates. Including the proper thicker throttle blades on the outer carbs and getting the linkage as well as the extended throttle shafts. If you were to price the parts out individually the kit is a great deal. Slightly expensive buy in but then you have everything you need to make it work right.

The outer carbs different on a properly set up 3X2 system. they have thicker throttle blades & no idle circuits. they basically act like a bucket with a hole in it when you go full throttle. Trying to get an engine to run with three regular carburetors will cause nothing but headaches.

All three of the carbs on my car have had the choke removed and the holes plugged. I still need to swap to the proper baseplates on the end carbs, I just bolted the stuff together so I would lose less parts. I figured the trade off of having to keep the car running until it warmed up a little was worth not having a choke wire/cable to deal with.

There is nothing like the sound of a set of three deuce's under WOT acceleration. The learning curve will be worth it, keep at it.

Greasy Chevy · Sep 14, 2011

Ok guys. Once again thanks for all the help and info.
I found this on eBay.
http://cgi.ebay.com/ebaymotors/CARB..._Accessories&hash=item56460a8231#ht_500wt_948

I sent the guy an email asking if they were all small bore side inlet. I haven't heard back yet but the action ends in 10 hours. For 120 shipped you think it's worth the gamble? Throttle blades seized but I'll be replacing those anyway.. And I have a known good carb for the center.

tommy · Sep 15, 2011

When I did my trips, that guy was selling them in 6 packs like that. One of the carb rebuild guys would buy them all up.

I was tickled to find one on the bay from a truck with the manual choke and all the cable brackets. No I don't know the year or size of the truck.

My 6 cyl 56 Ford has the original choke cable in the dash to use. I prefer manual chokes having learned to drive with them. The driver adjusts it for the conditions at that time.

It will end up being hidden by the aircleaner but I think it's cool none the less.

spark · Sep 15, 2011

you can replace almost every thing on these carbs, the venturi cluster is the exception (I think) float, needle and seat, power pump, jets, power valve power valve piston all replaceable.

you only need master rebuild kits.

note no power valve on secondaries, power piston is disabled.

you will need a good base (throttle blades) for the center carb.

new longer shafts and blades are available.

Greasy Chevy · Sep 15, 2011

Ok it looks like I got six carbs conning my way! Tommy what's the next way to clean the body's and get that bronze ish color to them?

Sky65 · Sep 18, 2011

Don't mean to hijack this thread but I am putting a 3x2 on my car. I rebuilt the carbs and set them up per the instructions that came with the new outer carb bases. The car runs but the outer carbs puke fuel from the atomizers will running and after shut down when it starts to warm up. I can screw the idle mixture screws in all the way on the center carb and makes little difference. Thoughts? Float level too high? I did set them and I have new float bowl needle/seats. Thanks

Don's Hot Rods · Sep 18, 2011

Maybe it isn't cool to reference a thread on another forum about this subject, but a very knowledgable hot rodder on a forum I am on did a pretty indepth write up on converting these to tripower use. If I shouldn't post this, sorry, but thought it might help someone out.

Don

http://www.clubhotrod.com/shop-talk/26886-tri-power-carbs-build.html

tommy · Sep 19, 2011

Greasy Chevy said: ↑

Ok it looks like I got six carbs conning my way! Tommy what's the next way to clean the body's and get that bronze ish color to them?
Click to expand...

I use a bead blaster.

Then I dip them in a 10% solution of this and water for 20 seconds.

You can vary the color by changing the strength of the solution and the time in the bath.

Don't forget you will have to modify the base throttle plates for the end carbs or buy the ones that are already modified. If you want to search I did a post on modifying the bases but good luck on finding it. It was a while ago now.

Old wolf · Sep 19, 2011

Its possible to have the engine idle on all three carbs & use progressive linkage to work the end carbs. The larger the engine & the smaller the carbs the easier it is to get it to idle on all three carbs. With a big enough engine you dont evnen need progressive linkage. My old corvair idled on both of the 1 bbl carbs and didnt use progressive linkage. OldWolf

falcongeorge · Mar 3, 2012

Don's Hot Rods said: ↑

Maybe it isn't cool to reference a thread on another forum about this subject, but a very knowledgable hot rodder on a forum I am on did a pretty indepth write up on converting these to tripower use. If I shouldn't post this, sorry, but thought it might help someone out.

Don

http://www.clubhotrod.com/shop-talk/26886-tri-power-carbs-build.html
Click to expand...

Just stumbled across this doing a google search for Rochester 2gc's, This is even better than the cat in the birthday cake post. I just printed that whole thread out to put in one of my binders. REAL good stuff there Don, thanks for posting this.

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