Carter RBS Vacuum Ports

[John Ha]

I rebuilt my Carter RBS and was looking at some of the photos of those available on the internet that show 2 vacuum port nipples on the mixture screw side. Mine has one vacuum port nipple and a threaded hole just below the nipple port (photo below with red arrow pointing to the threaded hole. Is there something that's supposed to go into the threaded hole?

TIA!

 

[Econoline]

Mine has that hole, but it isn't threaded, just a blind hole. I'd look in there with a light and see if there is a port in there, I suspect not. If there is put a screw in there with some thread sealant on it.

 

[chad]

It may depend in which sz motor'n make.
AMC wuz another make these went to.

Seh? U kinda say foagedbodit...

Tanks 4 da info/pic.

 

[Econoline]

Yup

Maybe someone tapped it to mount something? Maybe it was oem tapped for a dashpot mounting bracket. A/T carb. Mine came from a manual. I have seen pics of a port there to. Maybe on those it's a vapor can purge port? On mine it doesn't connect to the venturi bore.

 

[John Ha]

Thanks for all the replies!

It looks like it's a blind hole (sorry, should have mentioned that) but I was not completely sure because I could not see the sides of the bottom very well. It came on the used 250 I bought (supposedly from a 73 Maverick) but I was not completely sure that it was the original carb for that engine.

I guess I'll go with it like it is. If I notice a vacuum leak there I'll deal with it.

 

[chad]

U could look it up for a lill more info.
I like to just to acquire the understanding &/or rebuild.
Some Carters (this 1 too) have the stamped (a #/Ltr combo pounded, clear'n crisp, not cast, onto the side of the bottom flange).
Take a look'n lemmie know what's there.
Either that or go on-line to f/u...

 

[xctasy]

Rath Empire

https://www.youtube.com/watch?v=ZVRjDo60XJM


Later ones have the uses of the two Vacuum lines stamped on them



Our former board user Albert Penello's



He blocked his lower line off with the aftermarket Vac line caps,

its drilled through and stamped for the EGR equiped Ford Sixes .



Like the Daytona Holley 1904, the Carter RBS is around as a brand new Carburador....


http://www.autoclasico.com.mx/site/?p=101&itemid=32606



John Ha,

Note well

A very good book for unlocking historic Ford engineering practice...

"ROCHE III, George Charles. THE BEWILDERED SOCIETY"

https://www.antichay.com/pages/books/47 ... ed-society

ROCHE III, George Charles. THE BEWILDERED SOCIETY. New Rochelle, NY: Arlington House, [1972]. Small 4to., orange cloth in dust jacket. First Edition. Very Good in d/j. $50.00.

 

[chad]

tanks for da pic Dean. The 2 middle ones show me
how to set up the carb, I've never seen one on a vehicle.
Looks like they have the heat riser like my YF (don't C where to terminate it tho)
I C the 2 blk 'caps' and U need the plate under the carb i.e.
Red line to back of V/C & pcv, black 1 to the distributor?
It looks like the odder guy took the vac-to-dizzy offa the higher 'capped' line?

 

[xctasy]

tanks for da pic Dean. The 2 middle ones show me
how to set up the carb, I've never seen one on a vehicle.
Looks like they have the heat riser like my YF (don't C where to terminate it tho)
I C the 2 blk 'caps' and U need the plate under the carb i.e.
Red line to back of V/C & pcv, black 1 to the distributor?
It looks like the odder guy took the vac-to-dizzy offa the higher 'capped' line?

It looks like the odder guy took the vac-to-dizzy offa the higher 'capped' line?

On the RBS, It works like this....low Distributor, High, EGR.


But it can be done wrong and still work.

Its very important to note that Ford bought its carbs from Holley and Carter, but 1946's and 4180 Holleys were designed for Ford from stock Holley 1940/1945 and 4150/4160 designs, and then hacked about to suit Fords needs.

The RBS was an OMC marine, AMC and Jeep carb, Ford used it to clear the hood space without having to modify the air cleaner. The YFA required a new air cleaner to package in the 1975 250 engines.

you remember this Holley 1904/1940 SCV set up?



Manifold vac down low,
ported vac higher up,
and the Speed port is normally for Spark advance (UP HIGH).

On the Holley 1946



S= Spark for DSII ignition
V= Vacuum take off
E=EGR

On the common Mustang and Truck 5.0/5.8/6.1/7.0/7.5 liter 4bbl Holley 4180 carburetor has a "hybrid" spark port that feeds a portion of manifold vacuum to the distributor when the throttle is closed. Bottom on the throotle body.



A unique feature not shared with any other carburetors.

Up high is an EGR valve



Another member on another web site took the ported and manifold vacuums, and data logged them against Throttle Position sensor angle, and got a bit of difference in the vacuum readings.



That scews up your distibutor vacuum if its not factory standard, But it still works... just not properly.

excerpt from my favorite ever EGR post 12-14-2015

http://vb.foureyedpride.com/showthread. ... GR-working

Carbureted engines with EGR use two forms of ported vacuum, one for the distributor vacuum advance,
and the other for EGR. The two are timed differently. Distributor ported vacuum peaks at lighter throttle
openings than EGR vacuum. On the 4180C carb, the long thin 1/8" nipple on the front of the baseplate
is distributor ported vacuum, while the bent 1/8" nipple above and to the front of the choke housing is
for EGR vacuum.

Where things get a bit confusing, is when EGR vacuum is used for other functions.....

 

[John Ha]

U could look it up for a lill more info.
I like to just to acquire the understanding &/or rebuild.
Some Carters (this 1 too) have the stamped (a #/Ltr combo pounded, clear'n crisp, not cast, onto the side of the bottom flange).
Take a look'n lemmie know what's there.
Either that or go on-line to f/u...

Thanks! I had looked around before I posted the question (and when trying to make sure I got the right rebuild kit) and found that some carbs were stamped with numbers on the base flange. Unfortunately this one isn't.

 

[John Ha]

Rath Empire

https://www.youtube.com/watch?v=ZVRjDo60XJM

Later ones have the uses of the two Vacuum lines stamped on them

Our former board user Albert Penello's
He blocked his lower line off with the aftermarket Vac line caps,

its drilled through and stamped for the EGR equiped Ford Sixes .

Like the Daytona Holley 1904, the Carter RBS is around as a brand new Carburador....

http://www.autoclasico.com.mx/site/?p=101&itemid=32606

John Ha,

Note well

A very good book for unlocking historic Ford engineering practice...

"ROCHE III, George Charles. THE BEWILDERED SOCIETY"

ROCHE III, George Charles. THE BEWILDERED SOCIETY. New Rochelle, NY: Arlington House, [1972]. Small 4to., orange cloth in dust jacket. First Edition. Very Good in d/j. $50.00.

These are great photos. Thanks for posting them. The heat riser was an interesting learning experience. It comes from a cast "tube" in the exhaust manifold from bottom to top of the manifold between the center cylinders - the exhaust gases warm the casting which warms the air in the tube which then flows up from a port in the bottom of the manifold to the port at the top of the manifold into the heat riser tube to the choke. I had to fix the manifold because the tube casting was corroded away and the inside of the tube chamber was exposed directly to the exhaust. Hope my fix holds up but it will be a little while longer before I know - still working on getting everything plumbed and wired - very slowly.

And now for something completely different. Long ago I worked for Ford - their aerospace division. I'll have to take a look at the book you reference.

Thank you all VERY much for your help - it's greatly appreciated!!

 

[Econoline]

Looks like they have the heat riser like my YF (don't C where to terminate it tho)
I C the 2 blk 'caps' and U need the plate under the carb i.e.

Chad, that's more of an 'orientation adapter'. If you have one for a YF it should fit on the RBS, they have the same bolt spacing.

 

[chad]

Thanks, that helps, yet again.
It's more of a "lowers the hood" problem 4 me…lol.

Wish I had a pic of the other side too. I don't have that particular cable bracket (mine feeds frm Pass's side) either.
You're not using your RBS Seth. Y not?

 

[Econoline]

It's complicated, didn't you see my status update? It's a choke problem but the torque converter is to tight as well, so I need a carb that is tight until I can get that sorted. I will update my build with all this info eventually, but long story short... xctasy pointed me to a v6 aod converter but I couldn't find it. In all the stores and auto parts outlets they list 2 converts, low and medium stall. But like x said, there is another oem spec and I finally found a source for it from Oregon Performance Transmission. All the parts houses list the medium for 5.0 V8 and 3.8 V6, but OPT actually has the low 351 and up, the medium 302, and the high V6 and supercharged. To complicate it all, I don't know if the converter in my trans was behind a 302 or something bigger. But I am sure its not a V6 trans, b/c it came from an 80's Econoline. An interesting side effect of putting the chinese YFA on was putting all the timing back in and not pinging except under the worst scenario I can muster. An uber steep hill in 3rd @ 30-35, D avenue off 12th here in town. And only when I leaned into to it for a test. Still 92 octane, I don't think that's going to change. Maybe still carb issue though? It runs well in the idle and transition but seems to lack the oomph of the RBS but will still lite the tire if you lean in hard enough. I think it's partly a linkage problem(the difference), I changed the stroke size/length for clearance reasons. I'm going to revisit it and try and shorten the pedal stroke to what it is with the rbs. BTW, that YFA has a wider bolt center than the YF. The RBS is a great carb though. My only complaints with mine are due to the torque converter and the fact that I tweaked something when I rebuilt it and the choke started to bind when it was near closed, my fault. I'm going to fix it. I think it would be a better carb on a lrg log 200 than a 250 though. At least a mildly built 250. Mine maybe leaned out under load? I dunno. But a very responsive carb and could get up and go when it's asked to. Even with the TC problem, the carb was totally drivable. The YFA is only marginally better at idle in gear at a stop and a bit smoother over more weather at low throttle cruise. But it's a fine line and the YFA lives just on the other side b/c it's brand new. I'm confident that once the TC is swapped it won't matter, later efi anyway. If not there's going to be a bon fire ala Econoline. Don't invest too much in marshmallows just yet tho

 

[chad]

Thnx,
All the info is great 4 me, never even remember seein the RBS in a vehicle.
Don't like the jets bein in there "permanently" (pressed in).

Get my ol 170's "copper" back 2nite, boiled out, rodded (if needed, I think I have a goodun
don't need that) the core support attachment re-'soldered' to the side so I can re-hang it...
Luv the ol style radiators, just hope the 170 'goes' w/the 250...

How's ur swap? keep the 170 radiator or go up a step w/302, 5.0, etc?
:

 

[Econoline]

I used a 2 row Mustang V8 radiator w/1 1/8" core tubes. It cools great, no problems.

 

[chad]

Didja hafta make a "cross over"'? due to 'wrong side' in/out lets (frm bent8 to i6)?
Thanks Seth~

 

[Econoline]

No, the V8 and the 250 are the same, the 200-144 use the other configuration, at least in early mustang radiators.

 

[chad]

WoW, thank you...
Sorry 4 da hijack
:nono: