carter rbs question

Y

yodabiri

Well-known member
Hello all! I havent posted much in a while, been busy but came up with a small problem when i tried to put a carter rbs carb on my mustang. As my signature says, its got a 250 with a t5 that i swapped in there. I also fabricated a carb adapter that allows me to run my old autolite 1100 on the car. By the way, the 1100 is the only carb I have ever been able to get to work "well" on this car. I have tried carter yf (2 in fact), a 2bbl demon, a 2bbl holley, none of which ever worked nicely. My latest try was the carter RBS. I tried to put the carter RBS on there and got the car to idle properly, but when gas is applied, it runs like crap. It bucks, farts, hesitates, and occasionally stalls. The carb is a remaufactured one, so I did not have any reason to take it apart yet, but I guess I probably should. Has anybody run into anything like this with the RBS? Any suggestions.

Thanks in advance!
 
I'm running a RBS on my 250 and I did have quite a bit of trouble with it before the rebuild.
I even had a bit of the float break off and intermittently block the flow of gas!
...but since the rebuild and a new float she's been running like a champ.

Steve....
 
I run a rbs on my 200, I had a little trouble on my first one then bought a rebuilt one off ebay and it has run very well since.
 
Sorry to bust in...

How much was the RBS (how available, any standard 'range' in $s)?


:nono:
(With apologies) And now back 2 yer regularly scheduled...
 
Howdy Yoda and all:

The RBS is capable of running as smoothly as an 1100. I' ran one on my 250 for almost a year. If the engine ran fine with the 1100 and then didn't with the RBS, that is a strong indication that something is amiss in the carb. " The carb is a remaufactured one", is no guarantee. I can't remember very many "Rebuilt" that didn't have issues. My guess is that your RBS has problems in the transition circuit and/or accelerator pump and circuit. When you peer down the carb throat from the top, can you see a squirt of gas when working the throttle?

What distributor are you using? Recheck you spark plug wire hookup and distributor cap orientation. Have you checked for vacuum leaks. The RBS is a very simple carb. Not much can go wrong, but it can bet plugged up or restricted internally.

Keep it coming.

Adios, David
 
I purchased a carter rbs off ebay for $135, brand new nos still in the mfg box, with the yellowing literature. I put it on my freshly rebuilt 200 and it started right up, but did not run well. I did a rebuild, and now its perfect. The problem was in the transition circuit, the accelerator pump was NG. I was surprised when I took it apart and found that so many of the pieces were an interference fit. Never saw a carb like this before. But its doing alright, and with 215cfm its giving me a little more punch than the 185 cfm Autolite 1100. Make sure your dizzy is a match to the carb, in other words check for a spark control valve.
 
ponyrider200":1mg75f89 said:
I purchased a carter rbs off ebay for $135, brand new nos still in the mfg box, with the yellowing literature. I put it on my freshly rebuilt 200 and it started right up, but did not run well. I did a rebuild, and now its perfect. The problem was in the transition circuit, the accelerator pump was NG. I was surprised when I took it apart and found that so many of the pieces were an interference fit. Never saw a carb like this before. But its doing alright, and with 215cfm its giving me a little more punch than the 185 cfm Autolite 1100. Make sure your dizzy is a match to the carb, in other words check for a spark control valve.
Click to expand...

Yer G R E A T! Thanks so much. Just as Mr. David said, careful on the need 4 rebuild (kit available @ local prts dist?). No SCV here. Goin DSII as well. Need the RBS for it's low rise on a low hood w/a high deck 250/4.1 transplant in non OE app (in my sig). Can U cite me the reference for the flee-bay sale? May B more available thru them? Use PM if you'd like.

Thanks again,
'Nother Noreaster
 
I think i will do a rebuild on the carb. Could you guys tell me what car model and year I should tell the parts guy at autozone when I get the kit. They are unable to look up specific carb models for some reason. Also, I checked, and could not find any vacuum leaks, nor any distributor issues. I am running a DUI distributor, and it has served me well with the 1100 so far even with its SCV. The higher cfm rating of the carter is primarily why i got the thing in the first place. I will keep you guys updated on the progress.

Thanks for all the responses.
 
Howdy Back:

THe Carter RBS carb was the standard on '70 - '73 Mavericks and Comets with the 250 engine. It came specific to Manual or Auto trans and with or without AC. I don't think the differences will matter much on the rebuild kits. If I were looking I'd be inclined to go after a carb from a car that had an auto trans and no air. The cores from cars with auto trans usually (?) have less throttle shaft wear. Just strip off the linkage you don't need for your application. Most of the differences were in the fast idle linkage and auto kickdown linkage. THe AC carbs may have an extra circuit to kick up the idle when the AC comes on. I can give you some part # if you need them.

Keep us posted.

Adios, David
 
For the curious here's a pic of the RBS off a 'MAv 250 donated from a 'Stang V8 swap . Donor still can't get that 351 running right 8)

RBS1.jpg


Does RBS stand for Runs-But-Stalls? :roll:

HAve FUn
 
Jeesh Powerband, that carb don't seem right better trash it to me....
:LOL:
 
ponyrider200":2saen67p said:
Chad, I will check the ebay reference tonite, and post it tomorrow.
Click to expand...

Jesh, U & David are swell, heck - ford6 is the, ah, um, better not say those on-line...G R E A T!!!
I can't believe this stuff is available ($10 @ a junk yrd?). Everything gets crushed @ 10 yrs/o around here. 1 still-in-the-box is even more unbelievable. However the recyclers is more @ my price point (unemployed off the acreage).

Thanks ponyrider,
From A Bronk driver
 
Sorry to chime in so late,
I have RBS on my 250 and it runs MUCH better than all other carbs that I have tried:1940 manual choke, 1940 auto choke, Autolite 1100, Autolite 1101, HW5200,and HW5200 overbored to 27/29 mm venturies. Like others have mentioned, the remanufactured RBS I bought ran poorly, however the 30 dollar RBS core I bought on Ebay and rebuilt with a $20 rebuild kit ran great! This makes sense to me since this is the carb that was supposed to sit on top of that motor (for the Maverick/Comet). I think the 1101 would have been OK since it was used on some Mustangs with 250's, but I could not get my carb to work despite rebuilding a few times. I am running a DSII system.
Good luck!
Marc in SF
63 Comet 250
 
Thanks for all the responses. Last night my 1100 seems to have given up the ghost and crapped out on my 10 miles away from home. (still rebuildable, but I want to try my luck with the RBS) So i rebuilt the RBS today, and after a bit of tuning, got the car to idle nicely at ~550 or so. (maybe a bit more would be better). I took the car for a spin around the block, and it does not have the same problem with the rough running, but now when you press the gas, the car nearly stalls. I noticed when I was rebuilding the carb, the spring in the fuel (accelerator) pump is kinda weak and is very slow to allow the pump to go down when the gas is depressed. There was no replacement spring for the accelerator pump in the kit. Should I try to replace the spring with something stronger, or should I be looking elsewhere for the problem? I will let the carb sit overnight with the gasoline in the bowl, maybe that would soften (lubericate) the sliding of the pump. Please let me know if it seems I am heading in the right direction, or if I am just fighing windmills.


yoda
 
A stronger spring will not help your problem as the spring is for the return of the accelerator pump diaphragm. Sounds like you have linkage bind, have you cleaned on the linkage pivot points of rust and grime so that they move freely? On some have had to take apart and bead bast or polish the arms and rods with a wire brush.
 
I am not sure we are talking about the same spring. I am talking about the spring that goes around the accelerator pump shaft inside the fuel bowl. Also there is no binding from what i can tell as all of the throttle parts move freely, other than the aformentioned accelerator pump. So to describe it better; the accelerator is depressed, and the "fork" moves down, allowing the accelerator pump to move down as well. Only in my case the movement if the pump is very slow, slower than before the rebuild, as I am guessing the new rubber seal is much better than the old, and has a bit more friction on the walls.

yoda
 
Yoda,
did you pull off the air cleaner, hold open the choke with a wire or screw driver, look down into the carb, and open up the throttle lever quickly to check for a good fuel spray into the barrel? If you do not see or hear any spray it sounds to me like a bad accelerator pump. I am not sure about the springs. FYI I found this useful diagram and pump adjustment instructions:
http://www.tocmp.com/manuals/Carbs/Carter/RBS/1974Ford/index.htm
Good Luck-
Marc in SF
 
I did exactly that, looked down the throat of the carb while i pulled throttle lever, a small trickle, but not much more. When I pushed the pin of the accelerator pump down , there was a good healthy spray into the throat of the carb. So i am convinced now that it is indeed the accelerator pump rubber portion binding in the fuel bowl. I will replace the new one with the old part (luckily i saved it). I actually found another person with the same problem on another forum while googling the problem. He said his stumbling problem went away when he changed the accelerator pump back to his old one. Who knew that rebuilding the carb with new parts was a bad thing :unsure: . Anyways thanks for the input, I will get back to you all with any updates.

yoda
 
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