Carter BB Accelerator Pump Link Arm - FYI

[James_Douglas]

As part of my problem on the 1949 Desoto cutting out I ran across an interesting thing.  Turns out the on the 1946 to 1954 Carter BB (1BBL) carbs that Carter used a few different arms on the Accelerator pump.  I went through the listings, in my 4 inch think original carter catalog, for Desoto and Chrysler and came up with 2 part numbers for 90% of the carbs and then a couple more used on just one or two odd applications.

 

The interesting thing is that I pulled all of them off my 9 carb cores, all versions from 1946 to 1954 and guess what?  All most all of them were different.

 

Some had obviously been bent by people thinking they were going to solve some problem.  Some were in fact just different in either shape or length by a lot..

 

The link holes that the arm goes into are supposed to be the only way to adjust the pump stroke. I switched carbs on the '49 while dealing with the pump/filter/tank problem and this car was bogging at take off.  When I had the top of the car off and pushed down on the pump I got a good squirt.  When I put it all together and opened the throttle I did not.  Drove me nuts until I realized that the arm was not the correct one.

 

Now it work fine.  My point of making this post is that some of you may have arms that are incorrect and/or have been played with.  Be advised.

 

The only way to really check it is to put it on the bench and make sure that when the arm is in the hole for the longest stroke that the flat arm that pulls up the plunger goes all the way up.  The as you move the arm to the other two holes it should not go up as far. 

 

Learn something new every day.

 

Best, James

[Jeff Balazs]

Hi James;

As usual another interesting topic. One of your earlier posts helped me sort out a problem I had with the step up piston function. It seems to have been hanging in the up position. Thanks..... I was finally able to make sense of what was happening and get this sorted out.

 

I recently reset the accelerator pump linkage to the shortest stroke hole on my truck. I did this because it has been so hot here this year and supposedly this is the summer setting. I have noticed that it definitely does not have as much oomph off the line now. I wonder if changing to this setting was a good idea? Where do you set this on your car? Is it really a bad thing to have it set in the higher position?

 

Jeff

[James_Douglas]

Hi Jeff,

 

I use the center hole.  Here in SF it is always 65F.  Winter and Summer. 

 

The inside hole is the Short Stroke and the outside hole is the Long Stroke.  The things is, if the arm has been monkeyed with, the relative positions of the pump will be off.  What I am doing is making sure that on the Long Stroke hole (Throttle closed) that the Link Arm makes the flat arm that goes up into the carburetor is as far up as it can go.  Pick a different link arm or bend it so that is all the way up. 

 

Once this is correct, then as you move the link to the center hole or the inner hole you can customize the pump stroke to your particular engine/car load and local temperature.

 

The other thing I found is that there are some differences in the accelerator pump jet diameters. The linkage adjustment is how much gas total goes through the jet.  The jet sets the RATE at which that amount of gas is added into the airstream.  I had a carb with the wrong jet number.  Probably a rebuilder years ago put the wrong one in.  Back in the day people did play with such things for one reason or the other.  Also, back in the day, carb rebuilders took hundreds of carbs and tore them down and put all the parts in a bin. They then reassembled them from the bins.  The jets look the same, only if you take a magnifying glass and read the number can you tell the difference.  I suspect that some carbs were rebuilt with wrong parts.  Since this jet requires taking an aluminum plug out, it rarely gets checked by people these days.

 

Best, James

[Jeff Balazs]

Hi James;

I did go through the process of verifying that the jets, etc....that were in the carb matched what was spec'd. There are a few things that complicate this though. First off my truck is a fluid drive.......so it has a dash pot DTG1 Carter. I found some info on what jets were supposed to be in this and what I have match's this. But there is another wrinkle. The original engine a 218 was replaced with a later 230 which has been bored out. I don't know how much difference this makes.........but it stands to reason that the optimum settings could be a bit different for the larger engine.

 

From what I could see the accelerator pump arm did not look as if it had been messed about with. The engine internals are in very good shape. It has good compression and runs very quietly. The one issue I have had with it is that it always seemed to be running on the rich side. Try as I may I couldn't find what was causing it to run rich.......until I read your posting about the potential issue with the step up piston hanging up.

 

When I was addressing this I put the accelerator pump rod into the shortest stroke hole......thinking that might be beneficial. Fixing that step up piston has made a big difference. It no longer smells as if it is running rich and it definitely runs better when it is cold. I think now I will try the middle position on the accelerator pump and see if that restores the snappier acceleration I had before all this. I suspect that with the slightly larger displacement engine it might need a bit more fuel than it is getting on the lowest setting.

 

Jeff

[Don Coatney]

Hi James;

 First off my truck is a fluid drive.......so it has a dash pot DTG1 Carter. I found some info on what jets were supposed to be in this and what I have match's this. But there is another wrinkle. The original engine a 218 was replaced with a later 230 which has been bored out. I don't know how much difference this makes

 

Jeff

I did not know any 218CI engines were ever coupled to a fluid drive from the factory no matter what brand and I did not know any Dodge trucks ever came from the factory with a 218CI engine. Canadian vehicles may be an exception.

[Young Ed]

I did not know any 218CI engines were ever coupled to a fluid drive from the factory no matter what brand and I did not know any Dodge trucks ever came from the factory with a 218CI engine. Canadian vehicles may be an exception.

 

Lots of dodge trucks came with 218s. I do not know why but while the Dodge cars of the same years had a 230 the trucks had a 218. I believe early in the 39-47 truck series they switched from the 201 to the 218 and the 218 continued through most or all of the pilot house trucks. Thats where the 218 truck with fluid drive came in

[Jeff Balazs]

Don;

218s were standard fair in the smaller Pilothouse trucks. Even the ones with a FD like mine. I am pretty certain Merle's truck is a 218 FD. My T-342 230 serial #  traces back to a heavier 54 "F" series dump truck originally. As far as I can tell it would not have been coupled to a FD so some mods were done at some time. What all was done I don't know.......but I suspect the carb and manifolds,etc were just taken off the 218 and bolted onto the 230. I am not an expert on the subject but the truck engines (T series) were supposedly a little different internally than the auto engines.

 

Jeff

[Don Coatney]

Thank you Ed and Jeff, I was not aware of the Dodge trucks with the 218.

[james curl]

I have a 41 Dodge 218 engine from a coupe in my 48 P-15 and it came with a fluid drive and transmission.  I sent the fluid drive unit to Connecticut to one of our forum members.  1941 was the last year Dodge used the 218, the 42s were 230 CI engines.

[Jeff Balazs]

I went ahead and reset the accelerator pump rod to the center position and that really helped the acceleration. Much better now. I suppose the lowest setting is really only useful for extreme conditions like high altitude. Getting the carburation set up on this old truck has been far more of a challenge than I ever expected. I guess that is what you get when you buy something like this that isn't completely original.

 

Jeff

[Don Coatney]

I have been running dual Carter B&B's from day one on my Desoto 251CI engine. I have had both carburetors in the set in the close hole for the most volume from the accelerator pumps from day one with no issues. Out of the hole acceleration has always been great on my engine. I have not found any difference in the rod length or any different bends. Both of my carburetors were purchased from George Asche and were freshly rebuilt by him 10 or so years ago.

 

 

[Jeff Balazs]

Well that is interesting. I wonder if this setting works well because you have dual carbs? That position ( closest to the shaft ) is actually the short stroke extreme hot weather/ high altitude position on my truck. I can certainly see how this would be a more optimum setting for dual carbs. I believe that the farther away you get from the shaft the longer the stroke......and so more fuel is delivered to the engine under acceleration. It sure looked that way to me when I had my carb apart.

 

I just had the smog test station in my shop complex put my truck on the scope this morning. I will post the test results this weekend. It might be interesting to compare readings if any one else has done this. It wasn't an official smog test but the shop owner seemed to think the readings were pretty fair for a 60 year old truck. I just wanted to see if it was running lean or rich after making these adjustments.

 

Jeff

[Don Coatney]

I may be wrong but think about the distance of the stroke a bit. The most outboard position moves the pivot point less distance but with more leverage. The inner most position moves the pivot point more distance with less leverage this delivers more fuel quicker.

[Jeff Balazs]

Don;

I think that the longer stroke position (farthest from the shaft) moves a greater volume of fuel into the engine when the pedal is depressed. At least that is how it appeared to work to me.

 

Here is a copy of the readouts I got from my "unofficial" smog test. If anyone else has had their flathead run on one of these machine it might be interesting to see and compare the results.

 

Jeff

Edited June 7, 2014 by Jeff Balazs

[DJ194950]

Jeff if you have an smog test from another car that includes Ca. allowable limits to compare to your truck would also be very interesting.

 

Hope that there are no EPA officials looking at this site if you do post one!

 

Just threw my last test paper with my cars smog output and state std.s away about 2 weeks ago.

 

DJ

[Dick41]

Hi James:  This may come in a little late.  I am just catching up on my forum reading after vacation.  I spent about a week this past winter doing a rebuild on my B & B.  After rebuild, same as you.  On and off the engine twice....no squirt.   Finally noted the little cupped brass washer that is on the flat activation lever was catching 1/2 way up and was not activating the plunger.  Works fine now...except the flathead 6 is gone and a 318 is going in.

 

I was aided greatly by three videos, available for free viewing on line, at Mike's Carburetors.  I bought the rebuild kit from him.  He even consulted with me twice on the phone to figure out why the no squirt thing was happening.  These videos take you step by step, with him narrating, as you rebuild the B & B.   I have no $$$ interest in posting this.  Just want to give credit for good service. 

 

THIS VIDEO SHOWS CONTENTS OF THE KIT:

http://www.youtube.com/watch?feature=player_embedded&v=Ju-A6C0-4dk

PARTS ONE AND TWO COVER RE-ASSEMBLY OF THE CARBURETOR – SCROLL DOWN THE PAGE TO THE TWO PART VIDEO:

http://www.carburetor-blog.com/carter-bb-carburetor/

THIS ONE COVERS ADJUSTMENT OF THE THROTTLE PUMP

http://www.youtube.com/watch?v=kGCKYA8KIiw&feature=player_embedded

 

Hope this help you, or others, doing this B & B rebuild thing.

 

Dick41

[Don Coatney]

Don;

I think that the longer stroke position (farthest from the shaft) moves a greater volume of fuel into the engine when the pedal is depressed. At least that is how it appeared to work to me.

 

Here is a copy of the readouts I got from my "unofficial" smog test. If anyone else has had their flathead run on one of these machine it might be interesting to see and compare the results.

 

Jeffsmog test readings 001.jpg

Jeff;

You are correct. I was thinking the backwards. I was thinking the rod activated the pivot point but in fact the pivot point activates the rod. Sorry for the confusion.

[Jeff Balazs]

Don;

No worries......been there..... done that .....myself.

As I stated earlier I have really struggled with state of tune issues on my truck. At this point I am just trying to get it as close to optimum as possible. Don't want to do any long term damage to this engine if I can avoid it.

 

Jeff

[Jeff Balazs]

Hi Doug;

I was thinking that data like this from other Mopar 6 engines would be the most useful. I think trying to compare and make adjustments based on data from more modern designs isn't going to get you very far. Best scenario would be to know what sort of readings you should expect to see from the same engine in optimum tune. If there was enough of this type of data available on a sampling of our engines it could be very useful in determining how well we actually have our engine's running.

 

I got these readouts for the cost of a lunch. Now at least I have some numbers to do comparisons against when I make changes. I will probably stop by again from time to time just to see how these numbers look as I rack up some mileage.

 

Jeff