3 Dueces

[papastoyss]

I'm firmly of the opinion that the only thing worse than a carb is 2 or 3 of them but a close friend has asked me to try & get a stalled project running for him. It's a '58 Chevy wagon,350 sbc w/a swap meet 3/2 setup. The carbs are Rochester 2 bbls. & the end carbs have idle screws which I understand is a no no. Probably why they were at a swap meet. I know replacement base kits are available w/o idle circuits, are there any other options such as blocking the idle circuits in the existing carbs? He's painting my '57 Handyman project & I would like to help him out w/this, he paints & bodyworks everyone else's cars but has none of his projects running. Any ideas?

[kb426]

For an experiment, screw the outboard idle screws in all the way. It's been decades since I had multiple carbs so I don't remember much, but I believe all mine used the outboard idle screws. These were all Holleys on Fords. I always believed that you needed some fuel flow for them to idle properly. I may be way off on this.

[enjenjo]

Having been through this a couple times, there is more to "end" carbs that just the idle circuit. OE "end" Rochesters have no idle circuits in the base, thicker throttle plates, deleted power valves, and some of the air bleeds plugged. The purpose of the thicker throttle plates are for better sealing so air doesn't leak through them when the throttles are closed. The bases also have no transfer slots so the air can't leak through them either. Since there is no air flow through the end carbs with the throttles closed, the power valves are not needed. and since there are no chokes the air bleeds for the choke are plugged. They also have longer throttle shafts so the progressive linkage can clear every thing.

Can you use normal bases on as an end carb? Yes, but there is more to it than just screwing the needles closed. First you have to fill the transfer slots, and sand them smooth with the throttle bore. I use slightly thinned Lab Metal applied with a syringe.. You can replace the needles with a set screw and a lead shot with a little blue Loctite on it. At this point you should wax the inside of the throttle bores. You will need to buy the longer throttle shafts, clean the throttle plates thoroughly, and install the plates and shaft. Try to get them to seal as tightly as possible. With the throttle plates held closed, flow a bit of thinned Lab metal on the high side of the throttle plates on top, and the low side of the throttle plates on the bottom, usually this is two operations. Once the Lab Metal has set enough, open the throttle plates and let it finish setting. Now you should have a near perfect seal on the throttle plates.

Plug the air bleeds in the carb body, as well as the power valves, and you have an end carburetor. Your progressive linkage goes from the center carb to the front cab, and the front and rear carbs are connected with a straight rod.

I have seen people try to run the end carbs unmodified, but you get a really rich idle that can't be set low enough to reliably work right for street use. They are also rich through the transition, and it can't be tuned out without at least plugging the power valves.

[kb426]

This Hot Rod article says the same as Frank's excellent answer but has a listing for rebuilt base plates if you're interested.
http://www.hotrod.com/articles/hrdp-1102-rochester-2gc-carbs-rebuild/
This guy has parts also:   http://vintagespeed.com
I found this carb also: https://www.summitracing.com/parts/sum-2100e/overview/

[papastoyss]

This Hot Rod article says the same as Frank's excellent answer but has a listing for rebuilt base plates if you're interested.
http://www.hotrod.com/articles/hrdp-1102-rochester-2gc-carbs-rebuild/
This guy has parts also:   http://vintagespeed.com
I found this carb also: https://www.summitracing.com/parts/sum-2100e/overview/

Thanks guys, knew I would get the straight scoop here.