Technical Can someone please educate me on this please?

So I've an external dashpot on my Buick's Rochester carb, which I totally get but I've this built in one on the Carter AFB 1407 on my Lincoln that I just can't get my head around & can't find anything about on the internet, seeing as it's a 1959 carb. The linkage seems to push the dashpot down when the secondaries kick in... please feel free to educate me as I'm intrigued !

 

Looks like another accelerator pump. Can't say I have ever seen that before.

 

What they are calling a "dashpot". is an accelerator pump. Gives a shot of gas when you hit the throttle, to prevent a dead spot when you kick it.

 

I thought the same initially but is a dashpot

I thought the same but pump is the other side & 3 parts leaflets list it as a dashpot.

 

The accelerator pump is the other side ... & 3 different parts instructions list it as a dashpot.

 

What happens when you fill the bowl with gas and push it down? Does gas squirt out the squirters? Do both work like accelerator pumps? Or is it a damper that slows down the opening of the secondaries?

 

. . . Because it is a dashpot!


I've never seen that feature (hydraulic dashpot) before on an AFB. But a bit of online searching turned up this illustration from an old Carter Service Manual. The link below should give you some in-depth information on your carb's workings. It also shows this AFB with vacuum operated secondaries, another revelation for me.

https://www.thecarburetorshop.com/Service_Carter_AFB.pdf



Maybe @carbking will drop by and shed a bit of light on the subject. He's a member here and the above link is to his website.

 

Definitely not the former, only the pump on the other side does that BUT you may have inadvertently solved the puzzle because the dashpot goes down when the secondaries kick in, so maybe that is exactly what it does?

 

So when you push down on the damper piston with gas in the bowl, where does the gas go that the plunger is pushing? If it just byp***es, or goes back into the float chamber it is either a damper to slow the opening of the secondaries or slow the close. Depends on how it works.

 

Interesting - on mine, when the cam starts to open the secondaries, the pump pushes down, not up ... unless I received it with the cam set up wrong, will double check it tomorrow.

 

Sounds like maybe someone tried ***embling it as if it were a second accelerator pump. Or the linkage for it has been installed 180° out of phase somehow. Would be worth investigating more thoroughly.

 

Carter AFB carbs used on Lincoln from 1963 through 1968 used the internal dashpot.

Located on the opposite side of the carburetor from the accelerator pump; it functions exactly as an external dashpot as a "slow closing throttle" device for the primary side.

Yes, it looks like an accelerator pump, but has a different function.

The shaft has a vertical cavity with a check ball and 3 bleed holes. When the throttle is closed, fuel p***es through the bleed holes on one side of the ball, and the ball slows the fuel before it exits, thus slowing the rotation of the primary throttle shaft.

Early production were 64-196s, later production were 64-333s (that's from memory folks). I have been machining these things to go in our repair kits for decades. Surprisingly (at least to me) one of our most popular repair kits (possibly because we do include the dashpot).

Clay - Carter sold some AFB carburetors to Ford with the diaphragm secondary at Ford's request (the Ford folks were used to Holley). They also sold a smaller number to Chrysler. From memory (not generally a good idea, but the years really don't matter for this blurb, they were made from 1957 through 1959. Carter finally got tired of these, and told Ford no more, use our better air valve design. Like Carter, NOT my favorite Carter carburetor.

Maybe beginning was 1956, seems like Mercury used them on the 1956 WCFB.

Jon.

 

Thank you Jon, for the clarity ( I'm a UK customer of yours ). Could I ask you to take a look at my photos & tell me if that linkage set up is correct? I seem to recall that currently it pushes the pump down, when the cam / lobe opens the secondaries ... which I guess is wrong? Thanks in advance.

 

The linkage changed from early to late, what is the number on your carburetor? I haven't rebuilt one in 30 years, but will try to find a source (maybe I have one) to look at.

Jon.

 

Jon-
Thanks for popping in and clearing up another carburetor mystery. As I said, I never knew of an AFB with vacuum secondaries or a hydraulic dash pot. I do have a little experience with AFBs and AVSs from the mid 60s or so and newer but these two feature really caught me off guard. This stuff fascinates me and fortunately it didn't take me too long to find the link to your Carter Service Manual online. Thanks for posting this information on your site.


Now if I can just find some concrete info on the purpose of a "Killer Bleed" in an older Holley vacuum secondary 4 bbl. I saw it referenced in an illustration in an old Ford Performance Engines Guide. But there's no mention of its function in the guide that I can see. And so far online nobody else seems to want to talk about it either! I suspect that it's another one of those "OEM Ford Only" features.

 

Jon your memory is correct. The 1956 Mercury ***embly plant closest to the Carter plant installed the WCFB’s with the Holley looking vacuum secondary spring arrangement. So did the Lincolns. I have one for each rebuilt and some parts. I’ve shown photos here before when folks have said FOMOCO never used Carter WCFB’s. I believe the 260 hp 56 Merc dual quad setup for law enforcement and racing used the WCFB’s along with the Holley’s that the Fords used.

 

it just moves back to the bowl, the dashpot cylinder is in actuality a part of the float bowl.

 

Clay - while I posted the service information, raise your gl*** to the ghost of Carter Carburetor Company, as some 40 years ago they gave me permission to copy non-proprietary literature.

And I cannot help you with the Holley question.

Jon

 

That would be great if you could please Jon, as I would like to get this hooked up properly. The numbers I can find on it are 6- 1407. Thank you in advance.

 

Unfortunately, the 6-1407 is a casting number, not an identification number.

Check this link to my website:

https://www.thecarburetorshop.com/Carburetor_ID.htm#IDCarter

Jon

 

Mechanical Secondaries.

 

Here you go Jon, found them

 

I do not have one to look at, but here is the Carter adjustment specifications:

DASH POT: 1. 1/8 inch from the top of the bowl
cover to the top of the plunger shaft with primary
valves tightly closed. To adjust, bend the flat portion
of the dash pot lever. Check to be sure dash pot
lever does not contact bowl cover attaching screw.
2. 7/16 inch from the top of the bowl cover to the
top of the plunger shaft with primary valves wide
open. To adjust, bend stop lug on flat lever. Check
to be sure plunger shaft operates without sticking in
hole in bow! cover.

The following is from the Carter AFB circuit manual:



Jon

 

Jon. that was a big help, thank you. I played around with the mech & sure enough it now works as a dashpot & exactly to your measurements above!

Can you tell me I wonder, whether there should be a rubber washer & a steel washer on the mixture screws of a Rochester 4G. I'm having troubles with my other car (feel free to view the post elsewhere) & can't help wondering whether the washers I found on the mixture screws should be there, when on most all other carbs I have had, there were just the springs...

 

I am unaware of any Rochester 4G using, or needing, rubber seals on the mixture screws.

Carter used this on the YS 637s and 950s used on the underwater Jeep package.

Carter also used this on the AFB carbs (memory doesn't supply the numbers) used on the supercharged Studebakers, without the airbox.

Maybe if someone installed an aftermarket "blow-through" blower, they were added after the fact.

Jon

 

THANK YOU for such a swift reply. Appreciate it.

 

Hello again Jon, I finally found time to get this carb back together & hope to put it on the car this week & wondered if you could tell me the initial settings for the mixture screws please? Thank you.

 

Suggested initial setting on the idle mixture control screws are 2 turns ON THIS AFB; this is not a normal setting for AFB carburetors.

Jon

 

Jon, thank you so much for such a quick reply & all your help on this, much appreciated.

 

Hello again Jon, a little further advice for this UK resident if you could please? - I just had to have this carb apart again (wouldn't run & found dirty fuel & then overfilling / flooding) & cleaned it all out (with a plan to empty the tank of the dirty fuel).
Once I'd put the carb back together, I noticed it had never had (even the 1st time I stripped it) the little clips that hold the needle to the float, like my Buick's Rochester does. On inspecting two pieces of paper work I have relating to the carb, I found no reference to such clips in the breakdown & I just wondered if you could confirm please, whether it needs them or not? By the looks of the diagram, they just sit atop the end of the float... Please see attached pics.